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Reflections on the state of research: Indoor environmental quality
Indoor Air
Abstract
Abstract More than 30 years after the First International Indoor Climate Symposium, ten researchers from the USA, Slovakia, Sweden, and Denmark gathered to review the current status of indoor environmental research. We initiated our review with discussions during the 1-day meeting and followed that with parallel research and writing efforts culminating with internal review and revision cycles. In this paper, we present our choices for the most important research findings on indoor environmental quality from the past three decades followed by a discussion of the most important research questions in our field today. We then continue with a discussion on whether there are research areas for which we can ‘close the book’ and say that we already know what is needed. Finally, we discuss whether we can maintain our identity in the future or it is time to team up with new partners.
In the early years of this field, the accumulated knowledge was small and it was possible for any researcher to acquire a complete understanding. To do so has become impossible today as what we know has grown to exceed the learning capacity of any person. These circumstances challenge us to work collectively to synthesize what we do know and to define clearly what remains to be learned. If we fail to do these things well, we risk repeating research without memory, an inefficiency that we cannot afford.
... An integrated strategy combining energy efficiency along with biophilia can be addressed for a more efficient retrofitting. Moreover, since these buildings have poor conditions, it is important to ensure that indoor environmental quality (IEQ) goals are met alongside energy efficiency [30], so that a measure taken to improve one strategy does not lead to deteriorating others [31]. IEQ refers to the quality of a building's environment concerning its occupants [32]. ...
... Further expanding this idea of associating these strategies, we used the following methodology given in Figure 2. Moreover, since these buildings have poor conditions, it is important to ensure that indoor environmental quality (IEQ) goals are met alongside energy efficiency [30], so that a measure taken to improve one strategy does not lead to deteriorating others [31]. IEQ refers to the quality of a building's environment concerning its occupants [32]. ...
... An integrated strategy combining energy efficiency along with biophilia can be addressed for a more efficient retrofitting. Moreover, since these buildings have poor conditions, it is important to ensure that indoor environmental quality (IEQ) goals are met alongside energy efficiency [30], so that a measure taken to improve one strategy does not lead to deteriorating others [31]. IEQ refers to the quality of a building's environment concerning its occupants [32]. ...
... Further expanding this idea of associating these strategies, we used the following methodology given in Figure 2. Moreover, since these buildings have poor conditions, it is important to ensure that indoor environmental quality (IEQ) goals are met alongside energy efficiency [30], so that a measure taken to improve one strategy does not lead to deteriorating others [31]. IEQ refers to the quality of a building's environment concerning its occupants [32]. ...
The existing building stock is recognised as a major contributor to total energy consumption and related carbon emissions around the globe. There is increased attention on the retrofit of existing building stock, especially residential buildings, as a way of curbing energy consumption and carbon emissions. Within this context, human nature connectedness (HNC) has the potential of further amplifying the benefits of sustainable buildings both from an energy conservation practice and tangible improvements to users’ satisfaction, health, and wellbeing. This study attempts to show a case study of the potential of using HNC through the adoption of biophilic design principles to improve a residential building performance. A terrace house located in Sydney, NSW, was used as a case study and proposed retrofit scenarios were simulated with DesignBuilder® and Rhinoceros/Grasshopper with a view of improved daylighting, thermal comfort, and energy consumption. The building performance is improved in terms of daylighting, thermal comfort, and reduced energy consumption, additionally enhancing HNC.
... A main challenge identified in energy renovations of buildings is ensuring that indoor environmental quality (IEQ) goals are met at the same time [6]. Since buildings are complex systems, a measure intended to improve one condition could lead to the deterioration of others [7]. ...
... Since buildings are complex systems, a measure intended to improve one condition could lead to the deterioration of others [7]. Although research on IEQ has been extensive, at least for discrete parameters, there is still no clear answer as to how to define a good indoor environment from a holistic perspective [6], or how it should technically be measured, though suggestions have been made [8]. There are several expert assessment tools for evaluating renovations of multifamily housing based not only on energy efficiency, but also on changes in IEQ. ...
Sustainable housing that both creates good indoor environmental quality (IEQ) and avoids unnecessary energy use has proved difficult to realize. Renovations of multifamily houses provide an opportunity to find this balance. This study concerns whether tenants perceive that conditions for achieving sufficient IEQ with low energy use exist. Focus group interviews with 42 participants, in areas where the rents were in the lower range and included heating up to 21 °C, aimed to capture the tenants' perceptions of: IEQ and actions taken to regulate it; information and control; the connections between IEQ and energy use; and the role of the housing company. Good IEQ was crucial to interviewees, who described it as sufficient heat without draughts, ability to ventilate, and no disturbing sounds or smells. The main responsibility was attributed to the housing company, but daily regulation controlled by tenants. However, unclear interfaces between tenants and the systems that regulate IEQ make it difficult for tenants to act as a positive part of the system. Tenants did not link IEQ to energy use. A holistic view of the physical environment's affordances, including intuitive interfaces, could optimize the balance between good IEQ and energy use.
... Much research has been conducted on thermal comfort, IAQ and ventilation [20,27,58]. Thermal comfort and IAQ affects an occupant's well-being, health, perception of IEQ and productive performance [8,21]. ...
... People in buildings frequently report building-related health symptoms and sometimes develop building-related illnesses. Research has shown these health and comfort effects are associated with the characteristics of buildings, HVAC systems and the indoor environment [20,63]. The American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), International Organization for Standardization (ISO) and the European Committee for Standardization (CEN) have developed standards and guides for indoor air quality and ventilation and the criteria and recommendations in the international standards have been adopted as normative references by Australian national standards, guidelines and codes of practice [23,24,59,60,77]. ...
Climate change is leading to increased frequency, intensity and duration of heatwaves not only in Australia but globally. Children are among those who are most physically vulnerable to the changing climate. Schools buildings and facilities are critical infrastructure which are at risk of the adverse impacts of extreme weather conditions, particularly to the schools’ indoor environments. This chapter reviews the diverse policies on cooling and ventilation in educational facilities across Australia and brings together a multidisciplinary appraisal which can provide starting points for designers, building scientists and policy makers on: • Impact of building energy efficiency measures on the thermal comfort, IAQ and ventilation of educational facilities. • Health, educational outcomes and economic impacts of thermal comfort, IAQ and ventilation within educational facilities. • Australian and best practice international policies, standards and practices applicable to the thermal environment, IAQ and ventilation within P-12 educational facilities.
... In the early 1980s, this culminated with the recognition of sick building syndrome (Andersen and Gyntelberg, 2011;Rostron, 1997). Although building and furnishing materials are not unique in their negative contribution to indoor air quality and health, they are recognized as important contributors in this area (Andersen and Gyntelberg, 2011;Clausen et al., 2011). Since the 1970s, the increasing airtightness of buildings, leading to insufficient air exchange, has led to the buildup of indoor toxicants (Clausen et al., 2011, p. 221;Sundell et al., 2011). ...
... Since the 1970s, the increasing airtightness of buildings, leading to insufficient air exchange, has led to the buildup of indoor toxicants (Clausen et al., 2011, p. 221;Sundell et al., 2011). Consequently, research on indoor air quality and the impact of building and furnishing materials on human health has developed steadily since WWII, being especially proactive in the last 20À30 years (Clausen et al., 2011). Unfortunately, research is not considered to be keeping up with the need for new knowledge in this area (Clausen et al., 2011, pp. ...
Principles for Evaluating Building Materials in Sustainable Construction: Healthy and Sustainable Materials for the Built Environment provides a comprehensive overview of the issues associated with the selection of materials for sustainable construction, proposing a holistic and integrated approach.
The book evaluates the issues involved in choosing materials from an ecosystem services perspective, from the design stage to the impact of materials on the health of building users.
The three main sections of the book discuss building materials in relation to ecosystem services, the implications of materials choice at the design stage, and the impact of materials on building users and their health. The final section focuses on specific case studies that illustrate the richness of solutions that existed before the rise of contemporary construction and that are consistent with a sustainable approach to creating built environments. These are followed by modern examples which apply some, if not all, of the principles discussed in the first three sections of the book.
... Emails: l.oyedele@uwe.ac.uk; ayolook2001@yahoo.co.uk increased use of toxic materials, reduction of ventilation rates, tightening of building envelopes, and an overreliance of elaborate technologies (Wasley 2000; Crump, Dengel, and Swainson 2009; Carroon 2010). As suggested by Clausen et al. (2011, 222) in Reflections on the state of research, important research questions include: 'how can we ensure that IEQ [indoor environmental quality] goals are met as energy consumption to operate buildings is reduced?' Furthermore, Clausen et al. (2011) suggest the need for closer co-operation with green building councils to increase the awareness of IEQ and the effectiveness of meeting these needs in certification methods. ...
... A comprehensive understanding of causal relationships between major indoor air pollutants and building-related illnesses remains incomplete, despite numerous studies on IAQ and health (Mendell et al. 2002; Nøjgaard, Christensen, and Wolkoff 2005; Clausen et al. 2011 ). Further research is required to investigate the benefits of improved IAQ on occupant health and well-being in order to highlight the fundamental importance of healthy building design within the construction industry. ...
Purpose
– Concern of the deterioration of indoor environmental quality as a result of energy efficient building design strategies is growing. Apprehensions of the effect of airtight, super insulated envelopes, the reduction of infiltration, and the reliance on mechanical systems to provide adequate ventilation (air supply) is promoting emerging new research in this field. The purpose of this paper is to present the results of an indoor air quality (IAQ) and thermal comfort investigation in UK energy efficient homes, through a case study investigation.
Design/methodology/approach
– The case study dwellings consisted of a row of six new-build homes which utilize mechanical ventilation with heat recovery (MVHR) systems, are built to an average airtightness of 2m3/m2/hr at 50 Pascal’s, and constructed without a central heating system. Physical IAQ measurements and occupant interviews were conducted during the summer and winter months over a 24-hour period, to gain information on occupant activities, perception of the interior environment, building-related health and building use.
Findings
– The results suggest inadequate IAQ and perceived thermal comfort, insufficient use of purge ventilation, presence of fungal growth, significant variances in heating patterns, occurrence of sick building syndrome symptoms and issues with the MVHR system.
Practical implications
– The findings will provide relevant data on the applicability of airtight, mechanically ventilated homes in a UK climate, with particular reference to IAQ.
Originality/value
– IAQ data of this nature is essentially lacking, particularly in the UK context. The findings will aid the development of effective sustainable design strategies that are appropriate to localized climatic conditions and sensitive to the health of building occupants.
... Emails: l.oyedele@uwe.ac.uk; ayolook2001@yahoo.co.uk increased use of toxic materials, reduction of ventilation rates, tightening of building envelopes, and an overreliance of elaborate technologies (Wasley 2000;Crump, Dengel, and Swainson 2009;Carroon 2010). As suggested byClausen et al. (2011, 222) in Reflections on the state of research, important research questions include: 'how can we ensure that IEQ [indoor environmental quality] goals are met as energy consumption to operate buildings is reduced?' Furthermore,Clausen et al. (2011)suggest the need for closer co-operation with green building councils to increase the awareness of IEQ and the effectiveness of meeting these needs in certification methods. ...
... A comprehensive understanding of causal relationships between major indoor air pollutants and building-related illnesses remains incomplete, despite numerous studies on IAQ and health (Mendell et al. 2002;Nøjgaard, Christensen, and Wolkoff 2005;Clausen et al. 2011). Further research is required to investigate the benefits of improved IAQ on occupant health and well-being in order to highlight the fundamental importance of healthy building design within the construction industry. ...
The use of sustainable assessment methods in the UK is on the rise, anticipating the future regulatory trajectory towards zero carbon by 2016. The indisputable influence of sustainable rating tools on UK building regulations conveys the importance of evaluating their effectiveness in achieving true sustainable design, without adversely effecting human health and well-being. This paper reviews indoor air quality issues addressed by UK sustainable assessment tools, and the potential trade-offs between building energy conservation and indoor air quality. The barriers to effective adoption of indoor air quality strategies are investigated, including recommendations, suggestions and future research needs. The review identified a fundamental lack of indoor air quality criteria in sustainable assessment tools aimed at the residential sector. The consideration of occupants’ health and well-being should be paramount in any assessment scheme, and should not be overshadowed or obscured by the drive towards energy efficiency. A balance is essential.
... Fully controlling indoor emission sources to an acceptable level is not always feasible, therefore secondary measures such as the use of air disinfection devices, enable a means of ensuring a safe and healthy indoor environment for occupants. In a review of the current state of research for IEQ, Clausen et al [1] state that there is a need for good air cleaning technologies that can be used indoors and also note that the general society have questions relating to indoor air quality and are looking for ways they can protect their families. Consequently, a comprehensive assessment of the effectiveness of currently available air cleaning technologies is paramount. ...
... Theoretically, an increase in the ventilation rate will reduce the residence time of the particles in the UV irradiance zone (t uv ), thus reducing the percentage of microorganisms inactivated, (1). t uv = t res (h uv /h r ) (1) Where; t res is the residence time of a particle in the room (= 1/ACH), h uv is the height of the UV zone, and h r is the height of the room [2]. For the test chamber used in this study, the residence time of microorganisms in the UV zone is: 4.2 minutes at 3 ACH, 2.4 minutes at 6 ACH and 1.2 minutes at 9 ACH. ...
An experimental investigation was carried out to determine the effectiveness of an UltraViolet Germicidal Irradiation (UVGI) system for eradicating airborne pathogens in an indoor environment. Experimental and environmental conditions were varied and the resultant inactivated percentage of Staphylococcus aureus was measured. Results indicate that it is paramount to keep experimental parameters constant to achieve reliable and comparable results. In particular; the sampling plates used in the Andersen sampler must have a consistent depth of nutrient agar, and sufficient time (~ 40 mins) must be given for steady state conditions to be achieved prior to the commencement of air sampling.
Furthermore a change in environmental conditions such as ventilation regime and ventilation rate, were found to significantly influence the determination of the effectiveness of an upper-room UVGI system; with a ventilation regime of in low, out high resulting in an average of 16 % higher microorganism inactivation than a regime of in high, out low. The environmental conditions for which the device was deemed most effective, i.e. which resulted in the highest percentage of airborne microorganisms inactivated (96.0 ± 3.2 %) were: for a ventilation rate of 3 air changes per hour (ACH) and ventilation regime of in low, out high.
... IAQ has been identified as the fifth most important chronic health hazard nationally (Mendell, et al., 2002). Air quality in buildings can be directly related to occupant well-being and worker productivity (Clausen et al., 2011). Contemporary HVAC systems, specifically focusing on ventilation rates prescribed by ASHRAE have been the solution for most IAQ problems. ...
As the global human population expands, so do the bounds of the built environment. Advances in building technology are reactionary to the myriad of negative impacts buildings have on our global ecology: poor indoor air quality, inefficient envelope assemblies, and an unsustainable paradigm of energy use are just some of the numerous examples. There are many technological advancements that have the potential to be disruptive in the building industry, but the path towards commercialization of these technologies is often unclear and interrupted by the slow pace of product development and deployment in the construction industry. Sole source entities will not be able to develop and deploy these disruptive technologies without transdisciplinary collaboration and clear pathways for commercialization. This paper looks at an example of a next generation building technology moving to commercialization, beginning as an interdisciplinary collaboration in the academy within departments of architecture, science, and engineering. The project has become a reality by advancing the production of the system by working explicitly with architecture firms, manufacturers, and clients on real building installation projects. The technology is a modular plant wall system that improves indoor air quality (IAQ) in buildings by utilizing plants as a biomechanical filtration system that interconnects to a building's HVAC system. Potential benefits include reduced energy consumption, HVAC equipment requirements and the improved well-being and productivity of building occupants. This project could only be completed with full collaboration of industry and the academy. The proof of concept could only be developed where multiplicities of expertise can be found-biologists, designers, engineers, horticulturalists, etc. The proof of operation could only be tested in a full building scale integration where architects, contractors, manufacturers, regulatory agencies, etc. can be fully integrated into the execution and hold agency over the outcomes
... Residential indoor air quality (IAQ) is a challenging area of research due to difficulties associated with IAQ modeling (Academy & Sciences, 2011;Clausen et al., 2011;National Academy of Sciences, 2011;J. Sundell et al., 2011). ...
Poor air quality is considered to be one of the leading causes of global non- communicable disease and mortality. People in the United States spend 87% of their time in enclosed buildings and 69% of that time is spent in their residence. A building's envelope filters pollutants, such as particulate matter (PM) and ozone (O3), as air infiltrates into a building. The indoor environment is also directly affected by indoor sources due to outgassing from indoor materials or due to activities of the occupants such as cooking or cleaning. The outdoor environment around a building is in a constant state of change due to the diurnal cycle caused by solar radiation and on longer time scales caused by changing weather and climate. Therefore, it is important to understand the impacts that could arise from a changing climate. The CONTAM computer model is used to simulate indoor air quality of both fine-scale temporal measured test homes as well as representative U.S. building stock homes. It was found that CONTAM can closely simulate fine-scale temporal measured homes mean concentrations. The process and methodology used from the EPA STAR test homes was applied to simulate representative U.S. building stock homes from three 10-year periods centered on 2000, 2050 and 2090. It was found that the impacts due to climate change on IAQ are very location and home dependent, but tight homes with controllable outdoor air supply system have more to mitigate the effects.
... At the same time, there are many factors that affect users' subjective perceptions, including gender, age, education background, attitude, cognition, and so on [14]. IEQ is a description of the physical environmental parameters in a building, including thermal comfort, visual comfort, indoor air quality, acoustic comfort, etc. [15]. These parameters tend to show different degrees of importance for different buildings, and also reflect the influence of the user's behavioral experiences in the building. ...
The aim of this study is to determine the relationship between occupants’ emotional attitude, decision behavior, and environmental cognition toward window seats and learning efficiency and the mechanism of this relationship in public spaces (represented by academic libraries). Surveys were delivered to the academic library of Shanghai Jiao Tong University. A total of 280 valid face-to-face interview questionnaires was collected and analyzed for correlation and validation of theoretical models. The results show that learning experience, as a mediator of learning efficiency, has a significant impact on the model of occupants’ attitude toward window seat consumption. The impact mechanism was determined, and it indicated that in order to improve the learning efficiency of occupants, indoor re-planning should be carried out to improve the seat satisfaction and occupancy rate. This study introduces the concepts of service design and architectural consumption and constructs an occupant emotional consumption context with the window seat as the consumption product. In addition, it also has guiding value for seat reallocation in public buildings in the COVID-19 era. This theoretical framework provides a direction for the simulation of future construction consumption behavior.
... Our study also showed that among the studied species, Aptenia with higher growth index and larger leaf area showed better performance (growth and better surface coverage) than the other three species. Consistent with our results, Clozen et al. (2011) have already found that plants with large leaf areas have a better level of contaminant removal (Clausen et al., 2011). ...
... Our study also showed that among the studied species, Aptenia with higher growth index and larger leaf area showed better performance (growth and better surface coverage) than the other three species. Consistent with our results, Clozen et al. (2011) have already found that plants with large leaf areas have a better level of contaminant removal (Clausen et al., 2011). ...
Internal green wall systems can be combined with building structures to bring positive impacts on people's quality of life in interior spaces. However, obtaining green wall systems to optimize the performances of these living walls still needs research works. This study was conducted to investigate the plant, and air-quality performance resulted from combining ornamental plants and growing media types in an internal green wall system. The growing media types (mixed based on volume percentage) included cocopeat, perlite, cocopeat + perlite (1v:1v) and cocopeat + perlite + vermicompost (1v:1v:1v). The ornamental species included Peperomia magnoliiaefolia, Kalanchoe blossfeldiana, Aptenia cordifolia, and Carpobrotus edulis. There were significant differences among the plant species and the growing media types for improvement of the plant growth and morphophysiological factors. Organic-rich growing media of vermicompost along with perlite and cocopeat, combined with Aptenia cordifolia as the species can be used to create a horticulturally sustainable internal green wall, and also improve the health index in the building interior environments.
... In this extreme situation, the optimization of the DV system through a hybrid emergency ventilation system (EVS) becomes essential. Although increasing ventilation rate improves IAQ, the increase in energy use is a negative byproduct [11]. ...
Air pollution is detrimental to human health, causing several human illnesses. The industrial microenvironment generates high levels of indoor airborne pollutants, becoming a pervasive issue for workers. It is essential to improve the indoor air quality in this workplace by applying enhanced ventilation systems to minimize inhalation risk. Displacement ventilation is used in industrial buildings because of its stratified air distribution and low cost. However, in case of accidental pollutant release, an enhancement is needed to minimize inhalation exposure. This study proposes a hybrid emergency ventilation system using localized push-pull ventilation to improve the installed displacement ventilation system of a representative workshop. Computational fluid dynamics was applied to calculate steady-state indoor air flow and volume-averaged pollutant concentration. System performance was evaluated in terms of source position; a computer simulated person was integrated to the building to confirm effectiveness against personal inhalation. Results showed marked improvement in performance when push-pull technique was used: room-averaged concentration diminished up to 91% while ventilation rate only increased 4%. Inhaled pollutant mitigation was achieved but performance dependence against leakage source and personal position was confirmed.
... Formaldehyde is the simplest aldehyde form and is widely found in the air due to emissions from factories and automobiles, the volatilization of building materials, and so on [23,24]. The level of formaldehyde in polluted indoor air often exceeds the WHO limits by a dozen-fold (0.1 mg/m 3 ) [25]. ...
Indoor potted plants played an important role in the removal of air-borne VOCs. According to the difference between plant fresh extracts and boiled extracts on breakdown ability to the added formaldehyde, a simple quantitative evaluation method was used to identify the mechanisms of formaldehyde removal from the air by wild Taraxacum mongolicum Hand.-Mazz. and Plantago asiatica L.. After shoots exposure to formaldehyde (1.28 mg/m3 in the air) for 24 h, the formaldehyde removal rates of P. asiatica and T. mongolicum were 73.18 and 121.20 mg/h/kg FW (fresh weight), respectively. Formaldehyde can be transported from the air to the rhizosphere solution by plants, and the maximum rates of transmission by T. mongolicum and P. asiatica were 23.73 and 83.08 mg/h/kg FW, respectively. Although plant metabolism was responsible for formaldehyde loss in the air-plant-solution system, and the metabolic activity depended on the enzymatic and redox reactions in the plants, P. asiatica and T. mongolicum are still good candidate species for developing phyto-microbial technologies. The redox reaction was the main mechanism used by P. asiatica shoots to dissipate formaldehyde, while the enzymatic reaction was the main mechanism used by T. mongolicum. The higher oxidative potential and lower defensive enzyme activity in P. asiatica shoots led to its higher formaldehyde removal rate compared to T. mongolicum. Meanwhile, the stronger redox reaction ability in the T. mongolicum roots was partly responsible for its lower formaldehyde transmission rate. The results show two plants have strong tolerance to formaldehyde in the air and good formaldehyde removal ability.
... 62 Upadhyay and Kobayashi 45 pointed out that plants with a large leaf surface area are more suitable for removing pollutants. Clausen et al. 71 recommended to use a large leaf surface area in combination with an appropriate ventilation rate to obtain an appropriate performance with potted plants. It has also been stated that rhizosphere degradation (rhizoremediation) could play a major role in VOC removal by botanical biofiltration. ...
This paper reviews the state of art of vegetation systems and their effect on the indoor environmental quality (IEQ), based on scientific studies from the past 30 years. Some studies have shown that biophilic workspaces and interaction with plants may change human attitudes, behaviours, improve productivity and the overall well-being. Evapotranspiration from plants helps lowering the temperature around the planting environment and this can be utilised for air cooling and humidity control. Also, indoor greenery can be used to reduce sound levels as a passive acoustic insulation system. Living wall systems in combination with biofiltration are emerging technologies to provide beneficial effects on improvement of indoor comfort. Several studies have indicated that green systems may improve indoor air quality and that they have different pathways for pollutant removal of volatile organic compounds. The plant root zone in potted plants may be an effective area for removing volatile organic compounds under controlled conditions. In conclusion, the full capacity of plants in real-life settings will need to be clarified to establish the true pollutant-removal mechanisms and the general effect on IEQ. The effects of green systems in combination with mechanical elements such as conventional heating, ventilation and air conditioning would need to be studied.
... Lost work performance as a function of total ventilation rate (VR), at the 95th, 50th, and 5th estimate percentiles (EP) spanning the 90% confidence interval (CI) F I G U R E 3 Excess absence rate rEA as a function of total ventilation rate (VR), at the 95th, 50th, and 5th estimate percentiles (EP) spanning the 90% confidence interval (CI) matter with aerodynamic diameter <2.5 μm (PM 2.5 ) and ozone (O 3 )-can be measured reliably and have been shown in multiple large-population studies to elevate health risks ranging from asthma attack, to stroke, to premature mortality. Furthermore, a significant amount of exposure to outdoor pollutants occurs indoors 37,38 , and building operation's influence on indoor concentrations can be meaningfully modeled, 37,39 particularly given that real-time outdoor monitoring data are publicly available in many locations. ...
This article presents an outcome‐based ventilation (OBV) framework, which combines competing ventilation impacts into a monetized loss function ($/occ/h) used to inform ventilation rate decisions. The OBV framework, developed for U.S. offices, considers six outcomes of increasing ventilation: profitable outcomes realized from improvements in occupant work performance and sick‐leave absenteeism; health outcomes from occupant exposure to outdoor fine particles and ozone; and energy outcomes from electricity and natural gas usage. We used the literature to set low, medium, and high reference values for OBV loss function parameters, and evaluated the framework and outcome‐based ventilation rates using a simulated U.S. office stock dataset and a case study in New York City. With parameters for all outcomes set at medium values derived from literature‐based central estimates, higher ventilation rates’ profitable benefits dominated negative health and energy impacts, and the OBV framework suggested ventilation should be ≥ 45 L/s/occ, much higher than the baseline ~8.5 L/s/occ rate prescribed by ASHRAE 62.1. Only when combining very low parameter estimates for profitable impacts with very high ones for health and energy impacts were all outcomes on the same order. Even then, however, outcome‐based ventilation rates were often twice the baseline rate or more.
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... The composition of the outdoor environment may have an effect on IEQ as in the case of particulate matter from natural or artificial sources, while some IEQ parameters, such as certain volatile organic compounds (VOCs), may be exclusive of the outdoor environment [8]. Also, chemical processes between compounds present indoors can cause changes in IEQ [9]. ...
Background:
The aim of this paper was to examine associations between school building characteristics, indoor environmental quality (IEQ), and health responses using questionnaire data from both school principals and students.
Methods:
From 334 randomly sampled schools, 4248 sixth grade students from 297 schools participated in a questionnaire. From these schools, 134 principals returned questionnaires concerning 51 IEQ related questions of their school. Generalized linear mixed models (GLMM) were used to study the associations between IEQ indicators and existence of self-reported upper respiratory symptoms, while hierarchical Zero Inflated Poisson (ZIP)-models were used to model the number of symptoms.
Results:
Significant associations were established between existence of upper respiratory symptoms and unsatisfactory classroom temperature during the heating season (ORs 1.45 for too hot and cold, and 1.27 for too cold as compared to satisfactory temperature) and dampness or moisture damage during the year 2006-2007 (OR: 1.80 as compared to no moisture damage), respectively. The number of upper respiratory symptoms was significantly associated with inadequate ventilation and dampness or moisture damage. A higher number of missed school days due to respiratory infections were reported in schools with inadequate ventilation (RR: 1.16).
Conclusions:
The school level IEQ indicator variables described in this paper could explain a relatively large part of the school level variation observed in the self-reported upper respiratory symptoms and missed school days due to respiratory infections among students.
... 21 Another health problem associated with poor indoor environmental quality is an increase in a host of nonspecific symptoms, collectively labeled sick building syndrome (SBS). 4,22 SBS emerged as improved construction methods and insulation aimed at increasing building energy efficiency dramatically reduced the amount of air exchanged between indoor and outdoor environments. Construction with the aims of increasing energy efficiency and using environmentally friendly materials-now widely defined as green construction-has the potential to both improve resident health and decrease housing costs, but adequate ventilation standards must be maintained. ...
Objectives:
We examined associations of several health outcomes with green and conventional low-income housing, where the prevalence of morbidities and environmental pollutants is elevated.
Methods:
We used questionnaires and a visual inspection to compare sick building syndrome (SBS) symptoms and asthma-related morbidity among residents in multifamily units in Boston, Massachusetts, between March 2012 and May 2013. Follow-up was approximately 1 year later.
Results:
Adults living in green units reported 1.35 (95% confidence interval [CI] = 0.66, 2.05) fewer SBS symptoms than those living in conventional (control) homes (P < .001). Furthermore, asthmatic children living in green homes experienced substantially lower risk of asthma symptoms (odds ratio [OR] = 0.34; 95% CI = 0.12, 1.00), asthma attacks (OR = 0.31; 95% CI = 0.11, 0.88), hospital visits (OR = 0.24; 95% CI = 0.06, 0.88), and asthma-related school absences (OR = 0.21; 95% CI = 0.06, 0.74) than children living in conventional public housing.
Conclusions:
Participants living in green homes had improved health outcomes, which remained consistent over the study period. Green housing may provide a significant value in resource-poor settings where green construction or renovation could simultaneously reduce harmful indoor exposures, promote resident health, and reduce operational costs. (Am J Public Health. Published online ahead of print October 15, 2015: e1-e8. doi:10.2105/AJPH.2015.302793).
... Environmental quality also affects the future productivity of the work force. The effects of IEQ on adults and schoolage children all over the world are well documented (Almeida & de Freitas, 2014;Babayiğit et al., 2014;Clausen et al., 2011;Frontczak et al., 2012;Jepsen, 2001;Santamouris et al., 2014;Sarbu & Sebarchievici, 2013;Turunen et al., 2014;Zhang et al., 2013). Scant research focuses on the connections between environment and early learning. ...
The integration of environmental policies with political support for action on these policies is of prime significance for mobilization and progression of improving indoor environments. However, state licensing agencies and local county ordinances for child care centers do not universally follow these policies and standards. As a result, most early childhood educational programs operate without proper indoor environments. Indoor air quality, temperature, ventilation, daylighting, and acoustics are crucial factors for educational settings in early childhood education. This study documents the physical environment in early childhood education centers in three counties in Maryland. Results indicate that building performance and indoor air quality standards vary according to the socioeconomic status of children who attend early childhood programs, and environmental factors correlate with educational achievement (as measured by kindergarten readiness scores).
... Levin (2005, p. 1138) states that, " the integration of IAQ concerns in so-called 'sustainable' designs suffers from a lack of comprehensive assessment methods for building environmental performance and a lack of integration of the knowledge developed in the indoor air sciences during the past three decades " . Thus, greater collaboration between the interior environmental quality (IEQ) research community and green building councils is needed to increase the awareness of IEQ and the effectiveness of sustainable assessment schemes in ensuring these needs are met in practice (Clausen et al., 2011). It is on these bases that the study emerges, with the following aims: ...
Purpose
– Energy efficient building design strategies are growing in popularity, promoted through increased awareness of climate change, rising energy prices, global consciousness and a demand for energy security. To aid this design process, assessment tools such as Code for Sustainable Homes (CSHs) and Passivhaus were introduced in the UK. However, it is suggested that these tools prioritise energy efficiency over occupant health through a fundamental lack of attention to indoor air quality (IAQ). The purpose of this paper is to investigate IAQ in selected dwellings built using CSHs level 6, level 3 and Passivhaus homes in the UK.
Design/methodology/approach
– Using a case study approach, the investigation consisted of IAQ measurements during summer and winter months, occupant diaries and occupant interviews.
Findings
– The results from the IAQ measurements show the recommended maximum level of 1,000 ppm was breached in all three Code 6 and two Code 3 homes, with levels slightly below this limit in the two Passivhaus homes. Measurements found high levels of formaldehyde, carbon dioxide and low levels of relative humidity.
Practical implications
– There is a need for the adequate consideration of IAQ in sustainable assessment methods, including the use of mandatory credits to ensure occupant health is not disregarded in the drive towards zero carbon.
Originality/value
– These results can be used to recognise areas of improvement in the CSHs and Passivhaus standard, and the design of energy efficient homes in general. Research of this nature is essential to ensure occupant health is not sacrificed through the drive towards zero carbon.
... Long-term exposure to VOCs can cause damage to the liver, kidneys, and central nervous system. Short-term exposure to VOCs can cause eye and respiratory tract irritation, headaches, dizziness, visual disorders, fatigue, loss of coordination, allergic skin reactions, nausea, and memory impairment [4]- [7]. ...
Monitoring volatile organic compound (VOC) pollution levels in indoor environments is of great importance for the health and comfort of individuals, especially considering that people currently spend >80% of their time indoors. The primary aim of this paper is to design a low-power ZigBee sensor network and internode data reception control framework to use in the real-time acquisition and communication of data concerning air pollutant levels from VOCs. The network consists of end device sensors with photoionization detectors, routers that propagate the network over long distances, and a coordinator that communicates with a computer. The design is based on the ATmega16 microcontroller and the Atmel RF230 ZigBee module, which are used to effectively process communication data with low power consumption. Priority is given to power consumption and sensing efficiency, which are achieved by incorporating various smart tasking and power management protocols. The measured data are displayed on a computer monitor through a graphical user interface. The preliminary experimental results demonstrate that the wireless sensor network system can monitor VOC concentrations with a high level of accuracy and is thus suitable for automated environmental monitoring. Both good indoor air quality and energy conservation can be achieved by integrating the VOC monitoring system proposed in this paper with the residential integrated ventilation controller.
... Modeling has assisted in accounting for outdoor-indoor differences in the United States and Europe, though this approach is hindered by heterogeneity of indoor combustion conditions throughout the rest of the world. Characterization of outdoor-indoor exposures including activity patterns of a healthy, normal population continues to lag behind relative to other measures (Clausen et al., 2011;Diapouli et al., 2013;Kim et al., 2011;Mercier et al., 2011). ...
... Modeling has assisted in accounting for outdoor-indoor differences in the United States and Europe, though this approach is hindered by heterogeneity of indoor combustion conditions throughout the rest of the world. Characterization of outdoor-indoor exposures including activity patterns of a healthy, normal population continues to lag behind relative to other measures (Clausen et al., 2011;Diapouli et al., 2013;Kim et al., 2011;Mercier et al., 2011). ...
... Chen et al. (2003) investigated indoor air quality in air-conditioned train cabin and pointed out that volume flow rate of fresh air was a key factor to indoor air quality. Clausen et al. (2011) pointed out that important infectious diseases can be transmitted by airborne routes indoors. Zhang and Li (2012) studied the dispersion process of cough droplets of individual in a high speed rail cabin. ...
Air distribution system is very important to indoor air quality (IAQ) in China railway high-speed (CRH) train cabin. Air distribution systems in three different CRH train cabins are simulated and evaluated in this paper by using the computational fluid dynamic (CFD) method. CFD models of CRH1, CRH2 and CRH5 train cabins are developed and validated basing on the field experiments in three train cabins. Flow field, temperature field, and airflow pattern in the three train cabins are investigated respectively by using the CFD models developed. Four improved performance indexes which can eliminate influences of geometric dimension are utilized to evaluate the air distribution systems in the cabins. The cough droplets dispersion processes inside the CRH train cabins are simulated to investigate the cough droplets removal ability. Simulation results show that good airflow pattern is very critical to guarantee the uniform distribution of flow field, temperature field and thermal comfort in the train cabin. The air distribution system employed in CRH5 train cabin is the most efficient among the three train cabins. Moreover, CRH5 train cabin has stronger cough droplets removal ability than CRH1 and CRH2 train cabins. Air distribution system in CRH5 train cabin should be adopted in the next generation CRH train cabin in the future.
Indoor air quality (IAQ), specifically after the COVID-19 pandemic, has become an international issue, as humans spend 80–90% of their time in indoor microenvironments. Poor IAQ has been related to the sick-building syndrome, nasal and ocular irritations, allergies, and respiratory dysfunction, including premature deaths. Phytoremediation is a novel strategy to absorb, adsorb, assimilate or transfer/reduce air pollutants and improve the IAQ using plants. Hence, the current review aims to explore indoor plants' role in improving indoor air quality, including their purification capabilities. There is increasing evidence that various plant species (e.g., Ficus benjamina, Chlorophytum comosum, Draceana) or their parts can reliably reduce the concentration of numerous air pollutants in the indoor microenvironment and promote human wellbeing. However, the indoor air pollutants removal efficiency depends on the species of plant, various plant characteristics such as leaf size, thickness, area, photosynthetic activity, light intensity and part of plant involved, i.e., roots, leaves, wax, cuticle and stomata. Using indoor plants is one of the most cost-effective and reliable methods of making a healthier indoor environment. Better public health can be maintained at a lower cost, with less strain on the health care system, if more emphasis is placed on creating a biophilic atmosphere and increasing the use of indoor plants. However, there are no established criteria for the best indoor plants and the impact of indoor plants on various factors such as interior ventilation, temperature, humidity, etc. Therefore, further experimental research is needed that simulates the interior environment to monitor the impacts of indoor plants on factors such as humidity, temperature, ventilation, etc., in improving the microenvironment of a closed space/room.
AlGaN/GaN heterostructure-field effect transistor (HFET) has emerged as an outstanding wide band-gap semiconductor device since the last decade due to its inherent properties over conventional AlGaAs/GaAs and Si based devices of narrow band-gap. In this brief, the drain current, transconductance and its derivatives, intercept point, intermodulation distortion, and linearity distortion parameters of MOS AlGaN/GaN HFET are calculated and analysed.
Many studies have been conducted to assess the effects of indoor air quality (IAQ) on human health. However, there is still a lack of studies available about the adverse health effects on children’s respiratory health at Child Care Centers (CCC). The aim of this paper was to investigate the risk factors for respiratory symptoms and identify the root cause of IAQ problems at CCCs in Malaysia. The Modified American Thoracic Society and the Division of Lung Diseases (ATS-DLD-82) questionnaire was used to gather information from parents regarding their children’s respiratory symptoms. The IAQ parameters measured were for air temperature, humidity, carbon dioxide, carbon monoxide, respirable particles (PM2.5), viable bacteria and fungi count while the information on CCC characteristics and potential surrounding air pollutants were collected via a combination of area monitoring, inspection and interviews. Factors found to be significantly associated with persistent cough and/or cold were age, type of ventilation, location of CCC, floor area per child (<3.5 m2) and temperature. Children attending CCCs supplied by ACMV had the highest risk for prevalence of persistent productive cough [5.56 (CI: 2.20; 14.00)]. This study provided the baseline data on IAQ and possible factors that influenced indoor air contaminants, which could aid policy makers in formulating guidelines on IAQ for CCC in Malaysia.
The scientific articles and Indoor Air conference publications of the indoor air sciences (IAS) during the last 50 years are summarized. In total 7524 presentations, from 79 countries, have been made at Indoor Air conferences held between 1978 (49 presentations) and 2014 (1049 presentations). In the Web of Science 26,992 articles on indoor air research (with the word "indoor" as a search term) have been found (as of 1 Jan 2016) of which 70% were published during the last 10 years. The modern scientific history started in the 1970s with a question: "did indoor air pose a threat to health as did outdoor air?" Soon it was recognized that indoor air is more important, from a health point of view, than outdoor air. Topics of concern were first radon, environmental tobacco smoke and lung cancer, followed by volatile organic compounds, formaldehyde and sick building syndrome, house dust mites, asthma and allergies, Legionnaires disease and other airborne infections. Later emerged dampness/mold-associated allergies and today's concern with "modern exposures-modern diseases." Ventilation, thermal comfort, indoor air chemistry, semi volatile organic compounds, building simulation by computational fluid dynamics, and fine particulate matter are common topics today. From their beginning in Denmark and Sweden, then in the USA, the indoor air sciences now show increasing activity in East and Southeast Asia. This article is protected by copyright. All rights reserved.
Recently more information has emerged on possible adverse health effects associated with some building and furnishing materials, leading to or initiating legislative changes towards their reduction or elimination in many parts of the world. However, more general knowledge of the health risks associated with building and furnishing materials could make a significant contribution to improvements in indoor air quality. A study was set up to evaluate the level of knowledge in the relevant literature and the general population (from New Zealand, United Kingdom and the United States), and New Zealand architectural professionals. The results for vinyl and linoleum are presented, these being two flooring materials very similar in terms of appearance and application, but different in terms of chemical content and possible impact on health. The article indicates significant issues with the level of reported knowledge, with participants from the general population struggling to differentiate between vinyl and linoleum, and professionals reporting more prevalent use of vinyl, which they rate as less healthy.
The use of sustainable assessment methods in the UK is on the rise, emulating the future regulatory trajectory towards zero carbon by 2016. The indisputable influence of sustainable rating tools on UK building regulations conveys the importance of evaluating their effectiveness in achieving true sustainable design, without adversely effecting human health and wellbeing. This paper reviews the potential trade-offs between human and ecological health in sustainable building design, particularly between building energy conservation and indoor air quality. The barriers to effective adoption of indoor air quality strategies in sustainable assessment tools are investigated, including recommendations, suggestions and future research needs. The consideration of occupants' health and wellbeing should be paramount in any sustainability assessment method, particularly indoor air quality, thus should not be overshadowed or obscured by the drive towards energy efficiency. A balance is essential.
The quality of the indoor environment has been a matter of concern for some considerable time, because people spend a good deal of their time indoors, and the indoor environment affects their health. The government has tackled detrimental influences by means including the introduction of legislation on the composition of building materials, and the insulation and ventilation of buildings. It has also provided information to improve the ventilation habits of users and occupants. Some problems have nevertheless proven stubborn, inadequate ventilation in homes for example. New problems also crop up regularly, such as (neuro and reprotoxic) flame retardants from electronics that end up in household dust.
This study characterised indoor volatile organic compounds (VOCs) and investigated the effects of the dwelling characteristics, building materials, occupant activities and environmental conditions on indoor VOC concentrations in 40 dwellings located in Melbourne, Australia in 2008 and 2009. A total of 97 VOCs were identified. Nine VOCs, n-butane, 2-methyl-butane, toluene, formaldehyde, acetaldehyde, d-limonene, ethanol, 2-propanol and acetic acid, accounted for 68% of the sum of all VOCs. The median indoor concentrations of all VOCs were greater than those measured outdoors. The occupant density was positively associated with indoor VOC concentrations via occupant activities, including respiration and combustion. Terpenes were associated with the use of household cleaning and laundry products. A petroleum-like indoor VOC signature of alkanes and aromatics was associated with the proximity of major roads. The indoor VOC concentrations were negatively correlated (p <0.05) with ventilation. Levels of VOCs in these Australian dwellings were lower than those from previous studies in North America and Europe, probably due to a combination of an ongoing temporal decrease in indoor VOC concentrations and the leakier nature of Australian dwellings. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
How building stakeholders (e.g. owners, tenants, operators, and designers) understand impacts of indoor air quality (IAQ) and associated energy costs is unknown. We surveyed 112 stakeholders across the United States to ascertain their perceptions of their current IAQ and estimates of benefits and costs of, as well as willingness to pay for, IAQ improvements. Respondents' perceived IAQ scores correlated with the use of high efficiency filters but not with any other IAQ-improving technologies. We elicited their estimates of the impacts of a ventilation-filtration upgrade (VFU), i.e., doubling the ventilation rate from 20 to 40 cfm/person (9.5 to 19 L/s/person) and upgrading from a MERV 6 to 11 filter, and compared responses to our estimates derived from IAQ literature and energy modeling. Minorities of respondents thought the VFU would positively impact productivity (45%), absenteeism (23%), or health (39%). Respondents' annual VFU cost estimates (mean = 496, median = 32 per person), and the only yearly cost a plurality of respondents said they would pay for the VFU was $15 per person. Respondents holding green building credentials were not more likely to affirm the IAQ benefits of the VFU, and were less likely to be willing to pay for it. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Improved indoor air quality (IAQ) is one of the critical components of green building design. Green building tax credit (e.g., New York State Green Building Tax Credit (GBTC)) and certification programs (e.g., Leadership in Energy & Environmental Design (LEED)) require indoor air quality measures and compliance with allowable maximum concentrations of common indoor air pollutants. It is not yet entirely clear whether compliance with these programs results in improved IAQ and ultimately human health. As a case in point, annual indoor air quality measurements were conducted in a residential green high-rise building for five consecutive years by an industrial hygiene contractor to comply with the building's GBTC requirements. The implementation of green design measures resulted in better IAQ compared to data in references of conventional homes for some parameters, but could not be confirmed for others. Relative humidity and carbon dioxide were satisfactory according to existing standards. Formaldehyde levels during four out of five years were below the most recent proposed exposure limits found in the literature. To some degree, particulate matter (PM) levels were lower than that in studies from conventional residential buildings. Concentrations of Volatile Organic Compounds (VOCs) with known permissible exposure limits were below levels known to cause chronic health effects, but their concentrations were inconclusive regarding cancer health effects due to relatively high detection limits. Although measured indoor air parameters met all IAQ maximum allowable concentrations in GBTC and applicable LEED requirements at the time of sampling, we argue that these measurements were not sufficient to assess IAQ comprehensively because more sensitive sampling/analytical methods for PM and VOCs are needed; in addition, there is a need for a formal process to ensure rigor and adequacy of sampling and analysis methods. Also, we suggest that a comprehensive IAQ assessment should include mixed mode thermal comfort models, semi-volatile organic compounds, assessment of new chemicals, and permissible exposure levels of many known indoor VOCs and bioaerosols. Plus, the relationship between energy consumption and IAQ, and tenant education on health effects of indoor pollutants and their sources may need more attention in IAQ investigations in green buildings.
In the last decade, indoor air pollution has been unanimously recognised as a public health hazard worldwide, both in developed and developing countries. Accumulation of indoor air pollutants appears to significantly contribute to "sick building syndrome" (SBS) and other reported diseases in affected spaces. Botanical biofiltration has received a great deal of attention in the past decade, likely due its economical, environmental and social benefits, including its potential in the near future to be incorporated in both traditional and the new trend of sustainable zero-emission green buildings. This paper focuses on the potential and challenges of using botanical biofiltration for reducing the impact of gaseous pollutants in indoor environments. It is aimed at reviewing the current state of the art and the future research needs.
Abstract Negative pressure isolation wards are essential infection control facilities against airborne transmissible diseases. Airborne infectious particles are supposed to be contained in the isolation room. However, negative pressure may break down by door-opening action or by human movement. Understanding the interzonal transport of airborne infectious particles in the isolation wards can aid the design and operation strategy of isolation facilities. In this work, the interzonal migration of airborne infectious particles by human movement was studied experimentally in an isolation ward. Artificial saliva solution with benign E. coli bacteria was aerosolized to simulate bacterium-laden infectious particles. The interzonal migration of aerosolized bacteria was characterized by biological air sampling. Less than 1% of airborne infectious particles were transported to the higher pressure zone when door was closed. With human movement, 2.7% of the particles were transported from the anteroom to the corridor. From high-to-low pressure zones, as much as 20.7% of airborne infectious particles were migrated. Only a minimal amount of particles was transported from the corridor to the positive pressure nurses’ station. Infection risk of tuberculosis of the healthcare workers and other occupants in the isolation wards were also assessed based on the measured migration ratios.
Human movement is an important factor governing interzonal migration. It is the main cause of migration of airborne infectious particles to a relatively negative pressure zone. This study provides a set of experimentally obtained particle migration ratios by human movement. Other than serving as empirical data for further studies on the mechanics, these migration ratios can also be used to assess the infection risk for occupants in the isolation ward.
The association between passive exposure to tobacco smoke and respiratory symptoms was examined in a sample of 4,197 never-smoking adults. They constituted the never-smoking subsample of a random sample of 9,651 adults (age, 18 to 60 yr) in eight areas in Switzerland. Information on passive smoking exposure and standardized questions on respiratory symptoms were obtained via a questionnaire administered by trained examiners. After controlling for age, sex, body mass index (BMI), study area, atopy, and parental and sibling history, passive smoking exposure was associated with an elevated risk of wheezing apart from colds (odds ratio [OR] = 1.94, 95% Cl = 1.39 to 2.70), an elevated risk of bronchitis symptoms (OR = 1.59, 95% Cl = 1.17 to 2.15), an elevated risk of symptoms of chronic bronchitis (OR = 1.65, 95% Cl = 1.28 to 2.16), an elevated risk of dyspnea (OR = 1.45, 95% Cl = 1.20 to 1.76), and an elevated risk of physician diagnosed asthma (OR = 1.39, 95% Cl = 1.04 to 1.86). It was not associated with any increased risk of allergic rhinitis including hayfever. Adding a variable for low educational level, excluding subjects whose mother ever smoked or subjects with end-expiratory CO levels ≥ 7 ppm, and controlling for paternal smoking during childhood or occupational exposure had little impact on the association. The association of passive smoking exposure with dyspnea, wheeze, and asthma showed evidence of a dose-dependent increase with hours per day of exposure, whereas association with symptoms of bronchitis was stronger with years of exposure. A gradient of risk of chronic bronchitis was also seen by categories of years of exposure. Workplace exposure further increased the risk of wheezing apart from colds, dyspnea, and chronic bronchitis symptoms.
This study has used proton transfer reaction-mass spectrometry (PTR-MS) for direct air analyses of volatile products resulting from the reactions of ozone with human skin lipids. An initial series of small-scale in vitro and in vivo experiments were followed by experiments conducted with human subjects in a simulated office. The latter were conducted using realistic ozone mixing ratios (approximately 15 ppb with occupants present). Detected products included mono- and bifunctional compounds that contain carbonyl, carboxyl, or alpha-hydroxy ketone groups. Among these, three previously unreported dicarbonyls have been identified, and two previously unreported alpha-hydroxy ketones have been tentatively identified. The compounds detected in this study (excepting acetone) have been overlooked in surveys of indoor pollutants, reflecting the limitations of the analytical methods routinely used to monitor indoor air. The results are fully consistent with the Criegee mechanism for ozone reacting with squalene, the single most abundant unsaturated constituent of skin lipids, and several unsaturated fatty acid moieties in their free or esterified forms. Quantitative product analysis confirms that squalene is the major scavenger of ozone at the interface between room air and the human envelope. Reactions between ozone and human skin lipids reduce the mixing ratio of ozone in indoor air, but concomitantly increase the mixing ratios of volatile products and, presumably, skin surface concentrations of less volatile products. Some of the volatile products, especially the dicarbonyls, may be respiratory irritants. Some of the less volatile products may be skin irritants.
A review is presented of investigations of volatile organic compound (VOC) concentrations in indoor air of buildings of different classifications (dwellings, offices, schools, hospitals) and categories (established, new and complaint buildings). Measured concentrations obtained from the published literature and from research in progress overseas were pooled so that VOC concentration profiles could be derived for each building classification/category. Mean concentrations of individual compounds in established buildings were found to be generally below 50 μg/m3, with most below 5 μg/m3. Concentrations in new buildings were much greater, often by an order of magnitude or more, and appeared to arise from construction materials and building contents. The nature of these sources and approaches to reduce indoor air concentrations by limiting source VOC emissions is discussed. Total VOC (TVOC) concentrations were substantially higher than concentrations of any individual VOCs in all situations, reflecting the large number of compounds present, but interpretation of such measurements was limited by the lack of a common definition for TVOC relevant to occupant exposure.
During the first randomized intervention trial (RESPIRE: Randomized Exposure Study of Pollution Indoors and Respiratory Effects) in air pollution epidemiology, we pioneered application of passive carbon monoxide (CO) diffusion tubes to measure long-term personal exposures to woodsmoke. Here we report on the protocols and validations of the method, trends in personal exposure for mothers and their young children, and the efficacy of the introduced improved chimney stove in reducing personal exposures and kitchen concentrations. Passive diffusion tubes originally developed for industrial hygiene applications were deployed on a quarterly basis to measure 48-hour integrated personal carbon monoxide exposures among 515 children 0-18 months of age and 532 mothers aged 15-55 years and area samples in a subsample of 77 kitchens, in households randomized into control and intervention groups. Instrument comparisons among types of passive diffusion tubes and against a continuous electrochemical CO monitor indicated that tubes responded nonlinearly to CO, and regression calibration was used to reduce this bias. Before stove introduction, the baseline arithmetic (geometric) mean 48-h child (n=270), mother (n=529) and kitchen (n=65) levels were, respectively, 3.4 (2.8), 3.4 (2.8) and 10.2 (8.4) p.p.m. The between-group analysis of the 3355 post-baseline measurements found CO levels to be significantly lower among the intervention group during the trial period: kitchen levels: -90%; mothers: -61%; and children: -52% in geometric means. No significant deterioration in stove effect was observed over the 18 months of surveillance. The reliability of these findings is strengthened by the large sample size made feasible by these unobtrusive and inexpensive tubes, measurement error reduction through instrument calibration, and a randomized, longitudinal study design. These results from the first randomized trial of improved household energy technology in a developing country and demonstrate that a simple chimney stove can substantially reduce chronic exposures to harmful indoor air pollutants among women and infants.
To identify the indoor air quality issues about which Californians most often sought advice from a health department or a public information agency and to evaluate how well these agencies met the public's needs, members of the California Interagency Working Group (IWG) on Indoor Air Quality kept records of inquiries they received over a 30-month period from mid-1985 through 1987. Members of the IWG answered calls from residents of a least 49 of California's 58 counties. IWG members received more public inquiries about residences than about offices, educational institutions, commercial buildings, or medical facilities. However, each call about a residence probably represented fewer people at risk of exposure to a real or a potential problem than did calls about other types of buildings. Homeowners themselves asked the majority of the questions about residences, whereas a large number of the inquiries about office buildings were made, not by affected office workers, but by building managers, contractors, consultants, or company health and safety officers. The leading topics of concern in the residences were asbestos, chemical and biological contamination, and radon. In offices, chemical contamination, the ventilation system, biological contamination, asbestos, and tobacco smoke were the most frequently mentioned sources of problems. Callers often reported experiencing headaches, allergy symptoms, nose or throat irritation, and respiratory tract problems in connection with their complaints. IWG members directed a third of the calls elsewhere, of which half were referred to consultants or testing laboratories. The IWG's experience in the State of California could help other health departments prepare to face the public's increasing concern about indoor air pollution.
The association between passive exposure to tobacco smoke and respiratory symptoms was examined in a sample of 4,197 never-smoking adults. They constituted the never-smoking subsample of a random sample of 9,651 adults (age, 18 to 60 yr) in eight areas in Switzerland. Information on passive smoking exposure and standardized questions on respiratory symptoms were obtained via a questionnaire administered by trained examiners. After controlling for age, sex, body mass index (BMI), study area, atopy, and parental and sibling history, passive smoking exposure was associated with an elevated risk of wheezing apart from colds (odds ratio [OR] = 1.94, 95% CI = 1.39 to 2.70), an elevated risk of bronchitis symptoms (OR = 1.59, 95% CI = 1.17 to 2.15), an elevated risk of symptoms of chronic bronchitis (OR = 1.65, 95% CI = 1.28 to 2.16), an elevated risk of dyspnea (OR = 1.45, 95% CI = 1.20 to 1.76), and an elevated risk of physician diagnosed asthma (OR = 1.39, 95% CI = 1.04 to 1.86). It was not associated with any increased risk of allergic rhinitis including hayfever. Adding a variable for low educational level, excluding subjects whose mother ever smoked or subjects with end-expiratory CO levels > or = 7 ppm, and controlling for paternal smoking during childhood or occupational exposure had little impact on the association. The association of passive smoking exposure with dyspnea, wheeze, and asthma showed evidence of a dose-dependent increase with hours per day of exposure, whereas association with symptoms of bronchitis was stronger with years of exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
The study compares societal risk ratings by inhabitants of two countries which differ markedly in terms of geography, economics, politics, and ethnic background, but which are similar as regards media coverage. The two populations were represented by a sample of French students and a sample of Burkina Faso intellectuals. The overall Burkinabè mean ratings appeared much closer to the mean observed in France (and in the United States-roughly 40 out of 100) than the means reported for other countries like Norway or Hungary. The correlation between Burkinabè and French ratings was very high: .852. The findings argue in favor of a practically totally determinant effect of the media in risk perception.
To examine the relation between ventilation rate and occurrence of symptoms of the eyes, nose, throat, and skin as well as general symptoms such as lethargy and headache, often termed the sick building syndrome.
A cross sectional population based study was carried out in 399 workers from 14 mechanically ventilated office buildings without air recirculation or humidification, selected randomly from the Helsinki metropolitan area. The ventilation type and other characteristics of these buildings were recorded on a site visit and the ventilation in the rooms was assessed by measuring the airflow through the exhaust air outlets in the room. A questionnaire directed at workers inquired about the symptoms and perceived air quality and their possible personal and environmental determinants (response rate 81%). The outcomes were weekly work related symptoms experienced during the previous 12 months and symptom groups defined either by their anatomical location or hypothesised mechanism.
In logistic regression analysis, the adjusted odds ratio (OR) for any symptom of interest was 3.03 (95% confidence interval (95% CI) 1.13 to 8.10) in the very low ventilation category of below 5 l/s per person and 2.24 (0.89 to 5.65) in the high ventilation category of over 25 l/s per person compared with the reference (15- < 25 l/s). The ORs for ocular (1.27, 1.11 to 1.46), nasal (1.17, 1.06 to 1.29), skin symptoms (1.18, 1.05 to 1.32), and lethargy (1.09, 1.00 to 1.19) increased significantly by a unit decrease in ventilation from 25 to 0 l/s per person.
The results suggest that outdoor air ventilation rates below the optimal (15 to 25 l/s per person) increase the risk of the symptoms of sick building syndrome with the sources of pollutants present in mechanically ventilated office buildings. The Finnish guideline value is 10 l/s per person.
A critical review was conducted of the quantitative literature linking indoor air pollution from household use of biomass fuels with acute respiratory infections in young children, which is focused on, but not confined to, acute lower respiratory infection and pneumonia in children under two years in less developed countries. Biomass in the form of wood, crop residues, and animal dung is used in more than two fifths of the world's households as the principal fuel.
Medline and other electronic databases were used, but it was also necessary to secure literature from colleagues in less developed countries where not all publications are yet internationally indexed.
The studies of indoor air pollution from household biomass fuels are reasonably consistent and, as a group, show a strong significant increase in risk for exposed young children compared with those living in households using cleaner fuels or being otherwise less exposed. Not all studies were able to adjust for confounders, but most of those that did so found that strong and significant risks remained.
It seems that the relative risks are likely to be significant for the exposures considered here. Since acute lower respiratory infection is the chief cause of death in children in less developed countries, and exacts a larger burden of disease than any other disease category for the world population, even small additional risks due to such a ubiquitous exposure as air pollution have important public health implications. In the case of indoor air pollution in households using biomass fuels, the risks also seem to be fairly strong, presumably because of the high daily concentrations of pollutants found in such settings and the large amount of time young children spend with their mothers doing household cooking. Given the large vulnerable populations at risk, there is an urgent need to conduct randomised trials to increase confidence in the cause-effect relationship, to quantify the risk more precisely, to determine the degree of reduction in exposure required to significantly improve health, and to establish the effectiveness of interventions.
Associations have been found between day-to-day particulate air pollution and increased risk of various adverse health outcomes, including cardiopulmonary mortality. However, studies of health effects of long-term particulate air pollution have been less conclusive.
To assess the relationship between long-term exposure to fine particulate air pollution and all-cause, lung cancer, and cardiopulmonary mortality.
Vital status and cause of death data were collected by the American Cancer Society as part of the Cancer Prevention II study, an ongoing prospective mortality study, which enrolled approximately 1.2 million adults in 1982. Participants completed a questionnaire detailing individual risk factor data (age, sex, race, weight, height, smoking history, education, marital status, diet, alcohol consumption, and occupational exposures). The risk factor data for approximately 500 000 adults were linked with air pollution data for metropolitan areas throughout the United States and combined with vital status and cause of death data through December 31, 1998.
All-cause, lung cancer, and cardiopulmonary mortality.
Fine particulate and sulfur oxide--related pollution were associated with all-cause, lung cancer, and cardiopulmonary mortality. Each 10-microg/m(3) elevation in fine particulate air pollution was associated with approximately a 4%, 6%, and 8% increased risk of all-cause, cardiopulmonary, and lung cancer mortality, respectively. Measures of coarse particle fraction and total suspended particles were not consistently associated with mortality.
Long-term exposure to combustion-related fine particulate air pollution is an important environmental risk factor for cardiopulmonary and lung cancer mortality.
Some of the significant adverse impacts of used filters on indoor air quality of buildings and potential solutions are discussed. The presence of used filters in building results in occupants suffering from Sick Building Syndrome (SBS) symptoms. Used filters have an adverse impact on indoor air quality spreading different kinds of diseases among building occupants, including asthma and other allergic diseases. These filters are unable to prevent particulate and gaseous pollutants from entering the buildings through the ventilation system. The airflow through through these filters need to started earlier to control pollutants before buildings are occupied and improve indoor air quality. The development of low-polluting filtration techniques with higher efficiencies and lower pressure drops is another solution to prevent adverse impact of used filters in buildings.
Measurements of the indoor climate were performed in 14 town halls in Greater Copenhagen, Denmark, together with a questionnaire study and a clinical study of 4369 employees in the town halls and 14 affiliated buildings. The return rate for the questionnaire study was 80% and the participation rate for the clinical study 77%. The many indoor climate factors determined resulted in values mainly at the levels normally considered acceptable or in values in accordance with levels previously reported. The prevalence of work-related mucosal irritation and of work-related general symptoms in the employees differed highly between the individual town halls. The lowest prevalences of symptoms were found for the oldest town halls, whereas there were no statistically significant difference between naturally and mechanically ventilated buildings. The preliminary analyses showed that sex, job category, photoprinting, working with video display terminals, and handling carbonless paper correlated significantly with the presence of work-related mucosal irritation and general symptoms.
BACKGROUND—A critical review was conducted of the quantitative literature linking indoor air pollution from household use of biomass fuels with acute respiratory infections in young children, which is focused on, but not confined to, acute lower respiratory infection and pneumonia in children under two years in less developed countries. Biomass in the form of wood, crop residues, and animal dung is used in more than two fifths of the world's households as the principal fuel.
METHODS—Medline and other electronic databases were used, but it was also necessary to secure literature from colleagues in less developed countries where not all publications are yet internationally indexed.
RESULTS—The studies of indoor air pollution from household biomass fuels are reasonably consistent and, as a group, show a strong significant increase in risk for exposed young children compared with those living in households using cleaner fuels or being otherwise less exposed. Not all studies were able to adjust for confounders, but most of those that did so found that strong and significant risks remained.
CONCLUSIONS—It seems that the relative risks are likely to be significant for the exposures considered here. Since acute lower respiratory infection is the chief cause of death in children in less developed countries, and exacts a larger burden of disease than any other disease category for the world population, even small additional risks due to such a ubiquitous exposure as air pollution have important public health implications. In the case of indoor air pollution in households using biomass fuels, the risks also seem to be fairly strong, presumably because of the high daily concentrations of pollutants found in such settings and the large amount of time young children spend with their mothers doing household cooking. Given the large vulnerable populations at risk, there is an urgent need to conduct randomised trials to increase confidence in the cause-effect relationship, to quantify the risk more precisely, to determine the degree of reduction in exposure required to significantly improve health, and to establish the effectiveness of interventions.
Cited By (since 1996): 13
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Export Date: 4 February 2013
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Source: Scopus
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Author Address: Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, 1 University Station C1786, Austin, TX 78712-0273, United States
Author Address: Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, 221 Butler-Carlton Hall, Rolla, MO 65409, United States
This paper reports effects of reactions between ozone and selected terpenes on the concentrations and size distributions of airborne particles in a typical indoor setting. The studies were conducted in adjacent, identical offices. In the first set of experiments, known concentrations of ozone and a selected terpene (either d-limonene, alpha-terpinene, or a terpene-based cleaner whose major constituent is alpha-pinene) were deliberately introduced into one of the offices while the other office served as a control. Subsequent particle formation and redistribution were monitored with an eight-channel optical particle counter. Particle formation was observed in each terpene system, but was greatest in the case of d-limonene. The number of particles in the 0.1-0.2 mu m diameter size range was as much as 20 times larger in the office with deliberately supplemented ozone and d-limonene than in the office serving as the control. The concentration differences in the larger size ranges developed with time, indicating the importance of coagulation and condensation processes in this indoor environment. In the second set of experiments, d-limonene was deliberately introduced into one of the offices. but ozone was not supplemented in either office; instead, the indoor ozone concentrations were those that happened to be present (primarily as a consequence of outdoor-to-indoor transport). In the office that contained supplemental d-limonene, the concentrations of the 0.1-0.2 mu m particles tracked those of indoor ozone (the limiting reagent) and were as much as 10 times greater than levels measured in the comparable office that did not contain supplemental d-limonene. The results demonstrate that ozone/terpene reactions can be a significant source of sub-micron particles in indoor settings, and further illustrate the potential for reactions among commonly occurring indoor pollutants to markedly influence indoor environments.
The presence of Volatile Organic Compounds (VOC) in indoor air has in past decades often been associated with adverse health effects such as sensory irritation, odour and the more complex set of symptoms called the Sick Building Syndrome (SBS). More recently, a possible link between the increase in the prevalence of allergies throughout the industrialized areas of the world and exposure to elevated concentrations of VOCs has been suggested. In many cases, the total VOC (TVOC) is used as a measure of the concentration of air pollution and, by extension, as a measure of the health risk in non-industrial buildings. However, the TVOC concept has been questioned for a number of reasons, including the facts that it is an ambiguous concept, that individual VOCs making up the whole can be expected to give rise to different effects in people and that researchers have been using different definitions and interpretations of TVOC. This means that simple addition of the quantities of individual VOCs may not be relevant from a health point of view. Twelve researchers from the Nordic countries have reviewed the literature on VOC/TVOC and health. A search of the literature resulted in the identification of about 1100 articles, of which 120 were selected for further examination. A final review of the articles reduced their number to 67 that contained data on both exposure and health effects. The group concluded that indoor air pollution including VOC is most likely a cause of health effects and comfort problems in indoor environments in non-industrial buildings. However, the scientific literature is inconclusive with respect to TVOC as a risk index for health and comfort effects in buildings. Consequently, there is at present an inadequate scientific basis on which to establish limit values/guidelines for TVOC, both for air concentrations, and for emissions from building materials. The group concluded that continued research is required to establish a risk index for health and comfort effects for VOC in non-industrial buildings.
Volatile organic compounds (VOCs) have been measured in a freshly carpeted 20-m[sup 3] stainless-steel room in both the absence and presence of ozone (ozone concentrations ranging from 30 to 50 ppb, with one experiment conducted at 400 ppb). Four different types of carpeting were exposed, and in each set of experiments, the room was ventilated at 1 air exchange/h. The gas-phase concentrations of selected carpet emissions (e.g., 4-phenylcyclohexene, 4-vinylcyclohexene, and styrene) significantly decreased in the presence of ozone. Conversely, the concentrations of other compounds (e.g., formaldehyde, acetaldehyde, and aldehydes with between 5 and 10 carbons) significantly increased. Furthermore, the total concentration of VOCs increased markedly in the presence of ozone. The additional VOCs appear to have been generated by reactions between ozone and relatively nonvolatile compounds associated with the carpets. These studies suggest that VOCs measured within a building at elevated ozone levels (>30 ppb) may differ from those measured at lower ozone levels (
A survey of 1,462 people was carried out in Perth, West ern Australia to develop an understanding of the public perception and attitude towards the risk posed by indoor air pollutants. It was found that the public had a limited awareness of the issues involving the health risk posed by indoor air pollutants. The risk was perceived to be low, and a high proportion of the population (90.5%) indicated that they found the risk to be worse but accept able. The sample population indicated that they were not prepared to reduce the risk they perceived by spending money. Whilst the population perceived the health risk of indoor air pollutants to be low, they exhibited a high lev el of concern over the health risks of three specific indoor air pollutants, i.e. asbestos, pesticides and environmen tal tobacco smoke. The public perceived universities and research institutes to be the most credible sources of health-related information although the media was seen as the most important source of information on the health risks of indoor air pollutants.
The association between type of ventilation and outdoor-air flow rates and Sick Building Syndrome (SBS) and SBS symptoms was studied in a cross-sectional questionnaire and field study comprising 160 office buildings, and 260–2649 respondents with case-controls as well as prevalence comparisons. Measured ventilation rates were higher than required by most building codes and consisted of fresh-air (outdoor-air) inflow of 17±14 L/p and 2.0±1.3 air changes/h. Increased risk of SBS and elevated prevalence of general SBS symptoms were associated with low outdoor-air flow rates, presence of copying machines in office rooms, and ventilation operating hours was less than 10 h/d. There was a suspected association between SBS and air humidification, recirculation of exhaust air at high outdoor-air flow rates but not at low outdoor-air flow rates, and with natural or mechanical exhaust ventilation systems. SBS was not associated with the presence of a rotary heat exchanger or with the supply air temperature higher than the room air temperature.
The presence of Volatile Organic Compounds (VOC) in indoor air has in past decades often been associated with adverse health effects such as sensory irritation, odour and the more complex set of symptoms called the Sick Building Syndrome (SBS). More recently, a possible link between the increase in the prevalence of allergies throughout the industrialized areas of the world and exposure to elevated concentrations of VOCs has been suggested. In many cases, the total VOC (TVOC) is used as a measure of the concentration of air pollution and, by extension, as a measure of the health risk in non-industrial buildings. However, the TVOC concept has been questioned for a number of reasons, including the facts that it is an ambiguous concept, that individual VOCs making up the whole can be expected to give rise to different effects in people and that researchers have been using different definitions and interpretations of TVOC. This means that simple addition of the quantities of individual VOCs may not be relevant from a health point of view.
Ten healthy humans were exposed to combinations of volatile organic compounds (VOCs) and air temperature (0 mg/m3 and 10 mg/m3 of a mixture of 22 volatile organic compounds and 18, 22 and 26° C). Previously demonstrated effects of VOCs and thermal exposures were replicated. For the first time nasal cross-sectional areas and nasal volumes, as measured by acoustic rhinometry, were shown to decrease with decreasing temperature and increasing VOC exposure. Temperature and pollutant exposures affected air quality, the need for more ventilation, skin humidity on the forehead, sweating, acute sensory irritation and possibly watering eyes in an additive way. Interactions were found for odor intensity (p = 0.1), perceived facial skin temperature and dryness, general well-being, tear film stability, and nasal cavity dimension. The presence of interactions implies that in the future guidelines for acceptable indoor air concentrations of VOCs should depend on room air temperature.
The airway irritation of (+)-α-pinene, ozone, mixtures thereof, and formaldehyde was evaluated by a mouse bioassay, in which sensory irritation, bronchoconstriction, and pulmonary irritation were measured. The effects are distinguished by analysis of the respiratory parameters. Significant sensory irritation (assessed from reduction of mean respiratory rate) was observed by dynamic exposure of the mice, over a period of 30 min, to a ca. 22 s old reaction mixture of ozone and (+)-α-pinene from a Teflon flow tube. The starting concentrations were 6 ppm and 80 ppm, respectively, which were diluted and let into the exposure chamber. About 10% ozone remained unreacted (0.4 ppm), <0.2 ppm formaldehyde, <0.4 ppm pinonaldehyde, <2 ppm formic acid, and <1 ppm acetic acid were formed. These concentrations, as well as that of the unreacted (+)-α-pinene (51 ppm), were below established no effect levels. The mean reduction of the respiratory rate (30%) was significantly different (p≪0.001) from clean air, as well as from exposure of (+)-α-pinene, ozone, and formaldehyde themselves at the concentrations measured. Addition of the effects of the measured residual reactants and products cannot explain the observed sensory irritation effect. This suggests that one or more strong airway irritants have been formed. Therefore, oxidation reactions of common naturally occurring unsaturated compounds (e.g., terpenes) may be relevant for indoor air quality.
Total volatile organic compounds (TVOC) are determined in intake, room-supply and room air in 86 office rooms in 29 office buildings in northern Sweden. Measurements of formaldehyde were also made in room air. Building and room characteristics were identified and symptom reports collected from 1087 office workers. Concentrations of TVOC and formaldehyde in room air were low, with mean values of 71 µg/m3 and 31 µg/m3, respectively. The TVOC concentration was generally lower in room air than in supply air or intake air. The “loss” (difference in measured values) of TVOC from supply to room air was associated with raised concentrations of formaldehyde and raised prevalences of occupant symptoms. High TVOC concentrations in room air were associated with reduced prevalences of occupant symptoms.
Energy conservation and inadequate building technology sometimes cause a deterioration of indoor air quality and thereby produce potential health risks. Thus, some buildings may be diagnosed as “sick buildings”; the concept is commonly associated with acute sensory effects on humans. At present, the problem is frequently observed in newly built or remodelled preschool and office buildings. The symptoms include irritation of the eyes, the nose, and the throat, a sensation of dryness in the mucuos membranes and the skin, erythema of the skin, mental fatigue, and weak but persistant odors. This paper summarizes and examines these problems in a sensory-chemical as well as a social-psychological context. It is concluded that: (1) “Sick buildings” are basically a physical environment problem. (2) Sensations predominate reactions to “sick buildings” but the perceptual mechanisms are largely unknown. (3) Since there is a complex pattern of pollutants in indoor air, one cannot expect to find simple causal relationships. (4) Most reactions are largely nonspecific and refer to the chemical and somesthetic senses. The resultant perceptions are unitary, but multisensory in origin. Sensory interactions are known to occur. (5) The “sick building” syndrome is best understood by assuming that the sensory systems perform a pattern-recognition analysis. (6) It may partly be the result of a changed sensitivity in the populations exposed and/or a summation of numerous subthreshold sensory stimuli or interaction between gases-particles.
This study investigated the formation of secondary pollutants resulting from household product use in the presence of ozone. Experiments were conducted in a 50-m3 chamber simulating a residential room. The chamber was operated at conditions relevant to US residences in polluted areas during warm-weather seasons: an air exchange rate of 1.0 h−1 and an inlet ozone concentration of approximately 120 ppb, when included. Three products were used in separate experiments. An orange oil-based degreaser and a pine oil-based general-purpose cleaner were used for surface cleaning applications. A plug-in scented-oil air freshener (AFR) was operated for several days. Cleaning products were applied realistically with quantities scaled to simulate residential use rates. Concentrations of organic gases and secondary organic aerosol from the terpene-containing consumer products were measured with and without ozone introduction. In the absence of reactive chemicals, the chamber ozone level was approximately 60 ppb. Ozone was substantially consumed following cleaning product use, mainly by homogeneous reaction. For the AFR, ozone consumption was weaker and heterogeneous reaction with sorbed AFR-constituent VOCs was of similar magnitude to homogeneous reaction with continuously emitted constituents. Formaldehyde generation resulted from product use with ozone present, increasing indoor levels by the order of 10 ppb. Cleaning product use in the presence of ozone generated substantial fine particle concentrations (more than 100 μg m−3) in some experiments. Ozone consumption and elevated hydroxyl radical concentrations persisted for 10–12 h following brief cleaning events, indicating that secondary pollutant production can persist for extended periods.
Reactive building materials offer an opportunity to provide indoor air cleaning with minimal energy use. Laboratory and test house experiments provide evidence that indoor ozone concentrations can be diminished by activated carbon (AC) and unpainted gypsum wallboard (GWB) panels. These two materials are highly reactive with ozone and produce few byproducts. When measured in a 14.2 m3 stainless-steel chamber, the mean deposition velocities to the materials were 5.3 m h-1 for AC and 2.4 m h−1 for GWB for a variety of airflow and relative humidity conditions. The ozone decay rates for both the materials were also measured in an unoccupied 34.5 m3 bedroom under various mixing conditions. In this case, ozone removal increased relative to background by 27–100% with a 4.4 m2 panel of a reactive material placed on one wall of the bedroom. The ozone decay rate for the bedroom increased over background by approximately 2–3 h−1 for GWB and 2–7 h−1 for AC. Application of a mass balance model for a typical home demonstrates that effectiveness for ozone removal depends weakly on the air exchange rate and strongly on the panel material, panel area, and mixing conditions. An ozone removal effectiveness of over 80% is possible with sufficient panel area and positioning that provides elevated air speeds near the panels.
A nationwide survey of 4 373 office workers at 47 office sites was conducted to assess the prevalence of the sick building syndrome and to investigate associated factors. The office buildings sampled included those ventilated by either natural, mechanical, or forced air, or by air conditioning or some form of comfort cooling, including fan-coil, induction, and constant or variable air volume systems. Results showed a higher prevalence of reports of work-related symptoms of dry eyes, dry throut, stuffy/congested nose, itchy/watery eyes, runny nose, lethargy/tiredness, and headache in air conditioned buildings than in unconditioned buildings. Symptom prevalence was higher in buildings ventilated with water-based cooling systems, e.g., fan-coil or induction systems, than in buildings with all-air systems. A significant relationship was found between the type of humidification used in air-conditioned buildings (none, evaporative/spray, or steam) and the prevalence of itchy eyes, stuffy nose, lethargy, breathing difficulty, and chest tightness. Results also suggest that the “sick building syndrome” is associated with a variety of individual characteristics (sex, age), occupational factors (job type, length of video display unit use, occupancy duration in building, job stress), architectural features (type of office, type of building ventilation system), and psychological processes (perceived environmental control, perceived ambient conditions, perceived environmental satisfaction). A path analytic model is presented that suggests that psychological processes mediate the association between individual, occupational, and environmental characteristics and reports of the “sick building syndrome”.
The ongoing “Indoor Environment and Children’s Health” (IECH) study investigates the environmental risk factors in homes and their association with asthma and allergy among children aged 1–5 years. As part of the study, the homes of 500 children between 3 and 5 years of age were inspected. The selected children included 200 symptomatic children (cases) and 300 randomly selected children (bases). As part of the inspection, the concentration of carbon dioxide in the bedrooms of the children was continuously measured over an average of 2.5 days. The ventilation rates in the rooms during the nights when the children were sleeping in the room were calculated using a single-zone mass balance for the occupant-generated CO2. The calculated air change rates were log-normally distributed (R2 > 0.98). The geometric mean of the air change rates in both the case and the base group was 0.46 air changes per hour (h−1; geom. SD = 2.08 and 2.13, respectively). Approximately 57% of both cases and bases slept at a lower ventilation rate than the minimum required ventilation rate of 0.5 h−1 in new Danish dwellings. Only 32% of the bedrooms had an average CO2 concentration below 1000 ppm during the measured nights. Twenty-three percent of the rooms experienced at least a 20-minute period during the night when the CO2 concentration was above 2000 ppm and 6% of the rooms experienced concentrations above 3000 ppm. The average air change rate was higher with more people sleeping in the room. The air change rate did not change with the increasing outdoor temperature over the 10-week experimental period. The calculation method provides an estimate of the total airflow into the bedroom, including airflows both from outdoors and from adjacent spaces. To study the accuracy of the calculated air change rates and their deviation from the true outside air change rates, we calculated CO2 concentrations at different given air change rates using an indoor air quality and ventilation model (Contam). Subsequently we applied our calculation procedure to the obtained data. The air change rate calculated from the generated CO2 concentrations was found to be between 0% and 51% lower than the total air change rate defined in the input variables for the model. It was, however, higher than the true outside air change rate. The relative error depended on the position of the room in relation to the adjacent rooms, occupancy in the adjacent room, the nominal air change rate and room-to-room airflows.
It is generally believed that indoor air pollution, one way or another may cause indoor air complaints. However, any association between volatile organic compounds (VOCs) concentrations and increase of indoor climate complaints, like the sick-building syndrome symptoms, is not straightforward. The reported symptom rates of, in particular, eye and upper airway irritation cannot generally be explained by our present knowledge of common chemically non-reactive VOCs measured indoors. Recently, experimental evidence has shown those chemical reactions between ozone (either with or without nitrogen dioxide) and unsaturated organic compounds (e.g. from citrus and pine oils) produce strong eye and airway irritating species. These have not yet been well characterised by conventional sampling and analytical techniques. The chemical reactions can occur indoors, and there is indirect evidence that they are associated with eye and airway irritation. However, many other volatile and non-volatile organic compounds have not generally been measured which could equally well have potent biological effects and cause an increase of complaint rates, and posses a health/comfort risk. As a consequence, it is recommended to use a broader analytical window of organic compounds than the classic VOC window as defined by the World Health Organisation. It may include hitherto not yet sampled or identified intermediary species (e.g., radicals, hydroperoxides and ionic compounds like detergents) as well as species deposited onto particles. Additionally, sampling strategies including emission testing of building products should carefully be linked to the measurement of organic compounds that are expected, based on the best available toxicological knowledge, to have biological effects at indoor concentrations.
Volatile organic compounds (VOCs) are prevalent components of indoor air pollution. Among the approaches to remove VOCs from indoor air, photocatalytic oxidation (PCO) is regarded as a promising method. This paper is a review of the status of research on PCO purification of VOCs in indoor air. The review and discussion concentrate on the preparation and coating of various photocatalytic catalysts; different kinetic experiments and models; novel methods for measuring kinetic parameters; reaction pathways; intermediates generated by PCO; and an overview of various PCO reactors and their models described in the literature. Some recommendations are made for future work to evaluate the performance of photocatalytic catalysts, to reduce the generation of harmful intermediates and to design new PCO reactors with integrated UV source and reaction surface.
The quantity, identity, and distribution of biomass in indoor and outdoor aerosols are poorly described. This is not consistent with the current understanding of atmospheric chemistry or the microbiological characterization of aquatic and terrestrial environments. This knowledge gap is due to both difficulties in applying contemporary microbiological techniques to the low biomass concentrations present in aerosols, and the traditional reliance of aerosol researchers on culture-based techniques—the quantitative limitations and ecological biases of which have been well-documented and are now avoided in other environmental matrices. This article reviews the emergence of the polymerase chain reaction (PCR) as a nonculture-based method to determine the identity, distribution, and abundance of airborne microorganisms. To encourage the use of PCR-based techniques by a broad spectrum of aerosol researchers, emphasis is given to the critical, aerosol specific method issues of sample processing, DNA extraction, and PCR inhibition removal. These methods are synthesized into a generalized procedure for the PCR-based study of microbial aerosols—equally applicable to both indoor and outdoor aerosol environments.
The results of a pilot study in four Indian villages of personal exposure to total suspended particulates (TSP) and particulate benzo(a)pyrene (BaP) of women cooking on simple stoves using traditional biomass fuels are presented together with socioeconomic and fuel-use determinations. TSP exposures averaged nearly 7 mg m−3 and BaP about 4000 ng m −3 during the cooking period which occupied 10% of the year.The factors affecting indoor air pollution exposures in rural areas of developing countries are categorized and discussed by reference to the few published field measurements. Comparisons are made with other common exposures in urban and occupational settings. The sparse information indicates that rural exposures are relatively high. Subjects for future research are outlined and general policy implications mentioned.
A variety of organic compounds have been identified in size-fractionated indoor aerosol samples. These include aliphatic alcohols and phosphate esters not previously identified in ambient aerosols, as well as phthalate ester plasticizers whose numbers and relative abundances appear greater than those of outdoor samples. Several of the identified organics are evidence that relatively stable chemicals used within a building are likely to accumulate in the aerosol circulating throughout that building.
A general mathematical model is presented for predicting
the concentrations of chemically reactive compounds in indoor air. The model accounts for the effects of ventilation, filtration, heterogeneous removal, direct
emission, and photolytic and thermal chemical reactions.
The model is applied to the induction of photochemically
reactive pollutants into a museum gallery, and the predicted
NO, NO_x-NO, and O_3 concentrations are compared to measured data. The model predicts substantial production
of several species due to chemical reaction, including
HNO_2, HNO_3, NO_3, and N_2O_5. Circumstances in which homogeneous chemistry may assume particular importance
are identified and include buildings with glass walls, indoor combustion sources, and direct emission of olefins.
Indoor air pollution emerges as an important risk factor for acute respiratory infections (ARI) in developing countries. In many developing countries in addition to an increasing amount of tobacco smoke many homes contain high levels of smoke from the combustion of biofuels such as wood crop residues and animal dung for cooking or heating. In about half the worlds households such fuels are used for cooking daily usually without a flue or chimney and with poor ventilation. Results of investigations in 6 developing nations have shown the range of indoor pollution in such circumstances. The best single indicator for comparison of toxic noncarcinogenic effects is most likely respirable particulates similar to tar reported for cigarette emissions. Results of studies in animals suggest any difference in respiratory-system toxicity according to mass is not likely to be large. On the basis of the small amount of evidence available peak and daily exposures to indoor particulate levels in villages in developing countries seem to be about 20 times greater than in developed nations. The results of a semi-quantitative epidemiological study conducted in Nepal showed a direct relation between reported hours/day spent near the stove by infants and children aged under 2 years and episodes of life threatening acute respiratory infections. If one discounts the many possible confounding factors extrapolation shows that by moving all children into the lowest smoke exposure groups as much as 25% of moderate and severe infections would be eliminated. Extrapolation from studies of both ARI and environmental tobacco smoke also indicates indirectly the potential effect of indoor smoke from biofuels. Some environmental tobacco smoke studies have reported a dose-response relation between the number of cigarettes smoked in the home and respiratory symptoms in children. In sum biofuel smoke is likely to be a factor in ARI but its importance in relation to other risk factors is difficult to establish. It may be that prevention of acute respiratory infections could be best realized by initially addressing other risk factors or by addressing smoke solely in the context of broad based programs for several risk factors.
The uptake rates of low-molecular weight aldehydes and ketones by peace lily (Spathiphyllum clevelandii) and golden pothos (Epipremnum aureum) leaves at typical indoor ambient concentrations (10(1)-10(2) ppbv) were determined. The C3-C6 aldehydes and C4-C6 ketones were taken up by the plant leaves, but the C3 ketone acetone was not. The uptake rate normalized to the ambient concentration C(a) ranged from 7 to 19 mmol m(-2) s(-1) and from 2 to 7 mmol m(-2) s(-1) for the aldehydes and ketones, respectively. Longer-term fumigation results revealed that the total uptake amounts were 30-100 times as much as the amounts dissolved in the leaf, suggesting that volatile organic carbons are metabolized in the leaf and/or translocated through the petiole. The ratio of the intercellular concentration to the external (ambient) concentration (C(i)/C(a)) was significantly lower for most aldehydes than for most ketones. In particular, a linear unsaturated aldehyde, crotonaldehyde, had a C(i)/C(a) ratio of approximately 0, probably because of its highest solubility in water.
Indoor and outdoor airborne particle mass, protein, endotoxin and (1 --> 3)-beta-D-glucan in three size fractions (PM2.5, PM10, and TSP) were measured in ten single-family homes, along with quantifying household activities in the sampling room. Correlations between human activity levels and elevations in the indoor concentrations of particles and biomarkers were evaluated using four approaches for distinguishing activity levels: diurnal differences, the number of occupants, self-estimated occupancy, and activity strength. The concentrations of particles, protein, endotoxin and (1 --> 3)-beta-D-glucan in all three size fractions (PM < 2.5 microm, PM10-2.5, and PM >10 microm) were found, in most cases, to be significantly elevated during the day, and with higher activity levels in the room. The coarser fractions of particle mass and bioaerosols were more strongly correlated with human activity levels. Activity strength was the most statistically robust measure for relating human activities to indoor bioaerosol levels. While self-estimated activity and analysis of diurnal differences both offer reasonable (but not perfect) alternatives to activity strength, the number of occupants appears to be a weaker indicator for homes.
The short-term effects of particulate matter (PM) on mortality and morbidity differ by geographic location and season. Several hypotheses have been proposed for this variation, including different exposures with air conditioning (AC) versus open windows.
Bayesian hierarchical modeling was used to explore whether AC prevalence modified day-to-day associations between PM10 and mortality, and between PM2.5 and cardiovascular or respiratory hospitalizations, for those 65 years and older. We considered yearly, summer-only, and winter-only effect estimates and 2 types of AC (central and window units).
Communities with higher AC prevalence had lower PM effects. Associations were observed for cardiovascular hospitalizations and central AC. Each additional 20% of households with central AC was associated with a 43% decrease in PM2.5 effects on cardiovascular hospitalization. Central AC prevalence explained 17% of between-community variability in PM2.5 effect estimates for cardiovascular hospitalizations.
Higher AC prevalence was associated with lower health effect estimates for PM.
The association between total daily mortality and air pollution was investigated for a 1-year period (September 1985 through August 1986) in St. Louis and in the counties in eastern Tennessee surrounding Kingston/Harriman. The purpose of this study was to evaluate the relative importance of various measures of particulate and gaseous air pollution as predictors of daily mortality. Concentrations of inhalable particles (PM10), fine particles (PM2.5), the elemental composition of these particles, and aerosols acidity were measured daily during the period of study. The effect of each air pollutant on daily mortality was estimated after controlling for meteorologic and seasonal influences. Total mortality in St. Louis was found to increase 16% (95% CI-1 to 33%) for each 100 micrograms/m3 increase in PM10, and by 17% (95% CI-12 to 57%) in eastern Tennessee. Positive but progressively weaker associations were found with PM2.5, sulfate, and aerosol acidity concentrations in both communities. Associations with gaseous pollutants--sulfur dioxide, nitrogen dioxide, and ozone--were all far from statistical significance. Because of the short monitoring period for daily particulate air pollution, the power of this study to detect associations was limited. Nevertheless, statistically significant associations with PM10 were found in St. Louis, and, more importantly, the estimated effects were consistent between the two communities studied and with other reported analyses of the effects of particles on daily mortality. These data suggest that the acidity of particles is not as important in associations with daily mortality as the mass concentrations of particles.
The objective of this study was to determine the effects of passive smoking on functional lung growth in children and adolescents. It was hypothesized that passive smoking might reduce lung function growth, especially in susceptible children. The assumption was that those most susceptible would be children who started with low lung function, as it had been shown that they had slower growth of lung function, and start to decline earlier. There were 138 non-Hispanic Caucasian children and adolescents, ages 5 through 15, who had at least three satisfactory longitudinal lung function tests over a 13 year period in the Tucson epidemiological study of airway obstructive diseases. Those who started in childhood with normal function did not show any effect of passive smoking, nor did females who started with low lung function. Males starting with low lung function whose parents smoked showed definite changes. Their forced expiratory volume in 1 second (FEV1) grew even more slowly between ages 13 through 16, related primarily to continuous parental smoking. They also had higher rates of decline for FEV1 to forced vital capacity (FVC) ratio and maximum flow at 50% vital capacity to FVC ratios than either the low function group without passive smoking or the normal function groups. This was independent of any symptoms or diagnoses present in this male low function group.
Airborne transmission of infectious agents and associations of indoor air pollutants with respiratory illnesses are well documented. We hypothesized that energy conservation measures that tighten buildings also increase risks of respiratory infection among building occupants. At four Army training centers during a 47-month period, incidence rates of febrile acute respiratory disease were compared between basic trainees in modern (energy-efficient design and construction) and old barracks. Rates of febrile acute respiratory disease were significantly higher among trainees in modern barracks (adjusted relative risk estimate, 1.51; 95% confidence interval, 1.46 to 1.56), and relative risks were consistent at the four centers. These results support the hypothesis that tight buildings with closed ventilation systems significantly increase risks of respiratory-transmitted infection among congregated, immunologically susceptible occupants.
In a study in 29 health centre districts in Japan 91 540 non-smoking wives aged 40 and above were followed up for 14 years (1966-79), and standardised mortality rates for lung cancer were assessed according to the smoking habits of their husbands. Wives of heavy smokers were found to have a higher risk of developing lung cancer and a dose-response relation was observed. The relation between the husband's smoking and the wife's risk of developing lung cancer showed a similar pattern when analysed by age and occupation of the husband. The risk was particularly great in agricultural families when the husbands were aged 40-59 at enrolment. The husbands' smoking habit did not affect their wives' risk of dying from other disease such as stomach cancer, cervical cancer, and ischaemic heart disease. The risk of developing emphysema and asthma seemed to be higher in non-smoking wives of heavy smokers but the effect was not statistically significant. The husband's drinking habit seemed to have no effect on any causes of death in their wives, including lung cancer. These results indicate the possible importance of passive or indirect smoking as one of the causal factors of lung cancer. They also appear to explain the long-standing riddle of why many women develop lung cancer although they themselves are non-smokers. These results also cast doubt on the practice of assessing the relative risk of developing lung cancer in smokers by comparing them with non-smokers.
The concentration of house-dust mites (Dermatophagoides spp.) was investigated for four seasons in three locations in each of 50 Danish apartments. Simultaneously the absolute humidity was recorded and the previously known correlation between mite counts and indoor humidity was confirmed. It appeared, however, that apartments which had a low absolute indoor humidity in the winter period (due to low household load of water vapour) did not contain noticeable concentrations of house-dust mites in the summer and autumn despite the fact that the indoor absolute humidity in these apartments could be high enough to allow for a high peak-population of mites. Because of this it is suggested that in a temperate climate avoidance measures against house-dust mites should be supplemented at least by a drying out period in the winter, when this process is convenient to perform because of the low outdoor absolute humidity.
Thirty single-family homes with either high (> or = 2000 ng/g) or low (< or = 1000 ng/g) house-dust mite (HDM) allergen levels in mattress dust were examined for ventilation, thermal climate, and air quality (formaldehyde and total volatile organic compounds (TVOC). Elevated concentrations of HDM allergen in mattress and floor dust were associated with the difference in absolute humidity between indoor and outdoor air, as well as with low air-change rates of the home, particularly the bedroom. No correlation was found between concentration of TVOC or formaldehyde in bedroom air and HDM allergen concentration. In regions with a cold winter climate, the air-change rate of the home and the infiltration of outdoor air into the bedroom appear to be important for the infestation of HDM.
In a study in 29 health centre districts in Japan 91 540 non-smoking wives aged 40 and above were followed up for 14 years (1966-79), and standardised mortality rates for lung cancer were assessed according to the smoking habits of their husbands. Wives of heavy smokers were found to have a higher risk of developing lung cancer and a dose-response relation was observed. The relation between the husband's smoking and the wife's risk of developing lung cancer showed a similar pattern when analysed by age and occupation of the husband. The risk was particularly great in agricultural families when the husbands were aged 40-59 at enrolment. The husbands' smoking habit did not affect their wives' risk of dying from other disease such as stomach cancer, cervical cancer, and ischaemic heart disease. The risk of developing emphysema and asthma seemed to be higher in non-smoking wives of heavy smokers, but the effect was not statistically significant. The husband's drinking habit seemed to have no effect on any causes of death in their wives, including lung cancer. These results indicate the possible importance of passive or indirect smoking as one of the causal factors of lung cancer. They also appear to explain the long-standing riddle of why many women develop lung cancer although they themselves are non-smokers. These results also cast doubt on the practice of assessing the relative risk of developing lung cancer in smokers by comparing them with non-smokers.
Higher indoor concentrations of air pollutants due, in part, to lower ventilation rates are a potential cause of sick building syndrome (SBS) symptoms in office workers. The indoor carbon dioxide (CO2) concentration is an approximate surrogate for indoor concentrations of other occupant-generated pollutants and for ventilation rate per occupant. Using multivariate logistic regression (MLR) analyses, we evaluated the relationship between indoor CO2 concentrations and SBS symptoms in occupants from a probability sample of 41 U.S. office buildings. Two CO2 metrics were constructed: average workday indoor minus average outdoor CO2 (dCO2, range 6-418 ppm), and maximum indoor 1-h moving average CO2 minus outdoor CO2 concentrations (dCO2MAX). MLR analyses quantified dCO2/SBS symptom associations, adjusting for personal and environmental factors. A dose-response relationship (p < 0.05) with odds ratios per 100 ppm dCO2 ranging from 1.2 to 1.5 for sore throat, nose/sinus, tight chest, and wheezing was observed. The dCO2MAX/SBS regression results were similar.
We analyzed 1994 sick leave for 3,720 hourly employees of a large Massachusetts manufacturer, in 40 buildings with 115 independently ventilated work areas. Corporate records identified building characteristics and IEQ complaints. We rated ventilation as moderate (approximately 25 cfm/person, 12 ls-1) or high (approximately 50 cfm/person, 24 ls-1) outdoor air supply based on knowledge of ventilation systems and CO2 measurements on a subset of work areas, and used Poisson regression to analyze sick leave controlled for age, gender, seniority, hours of non-illness absence, shift, ethnicity, crowding, and type of job (office, technical, or manufacturing worker). We found consistent associations of increased sick leave with lower levels of outdoor air supply and IEQ complaints. Among office workers, the relative risk for short-term sick leave was 1.53 (95% confidence 1.22-1.92) with lower ventilation, and 1.52 (1.18-1.97) in areas with IEQ complaints. The effect of ventilation was independent of IEQ complaints and among those exposed to lower outdoor air supply rates the attributable risk of short-term sick leave was 35%. The cost of sick leave attributable to ventilation at current recommended rates was estimated as 400 per employee per year may be obtained with increased ventilation. Thus, currently recommended levels of outdoor air supply may be associated with significant morbidity, and lost productivity on a national scale could be as much as $22.8 billion per year. Additional studies of IEQ impacts on productivity and sick leave, and the mechanisms underlying the apparent association are needed.