Pawel Wargocki

• PhD
• Technical University of Denmark

[Open Access] While healthy buildings are investigated in academic research, practice, and policy, they often fail to address the needs and gaps due to insufficient knowledge transfer between them. Moreover, there is no general definition of healthy buildings that could act as a reference for different stakeholders of the building sector. Therefore...

In-duct ultraviolet germicidal irradiation systems (ID-UVs) is a promising technology for the development of biosecure buildings. This study explored the Computational Fluid Dynamics (CFD) method for accurately predicting the inactivation efficiency of ID-UVs. The results showed that the setting of ‘Divisions’ is crucial to the accuracy of radiatio...

Humans are known to be a continuous and potent indoor source of volatile organic compounds (VOCs). However, little is known about how personal hygiene, in terms of showering frequency, can influence these emissions and their impact on indoor air chemistry involving ozone. In this study, we characterized the VOC composition of the air in a controlle...

The in-duct ultraviolet germicidal irradiation system (ID-UVs) with ribs has been revealed to be effective in reducing the risk of biological contamination, and optimization of its UV radiation distribution is expected to further improve the inactivation performance. In this study, the Critical Survival Fraction Probability (CSFP) and Maximal Beara...

A major component of human skin oil is squalene, a highly unsaturated hydrocarbon that protects the skin from atmospheric oxidants. Skin oil, and thus squalene, is continuously replenished on the skin surface. Squalene is also quickly consumed through reactions with ozone and other oxidants. This study examined the extent of squalene depletion in t...

If some countries lead by example, standards may increasingly become normalized

Attaching ribs on duct walls is an effective way to improve the inactivation efficiency of in-duct UVGI systems (ID-UVs), and this study explored the optimal rib design. The Critical Survival Fraction Probability (CSFP) and Maximal Bearable UV Dose (MBUD) methods were employed as indicators. Results showed that ID-UVs with ribs could be optimized b...

The COVID-19 pandemic brought about a rapid and dramatic shift in the number of people working from home. For ASHRAE, the shift to more work from home has an impact directly on its members who work from home and indirectly on those ASHRAE members serve. Most notably, key metrics for performance of the built environment, including occupant health, p...

Occupant behaviour is a significant factor affecting the quality of the indoor environment (IEQ), which can have implications on the comfort and cognitive function of children in educational settings. The New Zealand (NZ) Ministry of Education (MoE) oversees more than 35,000 classrooms within 2,538 schools distributed across six climatic regions. T...

Humans are the primary sources of CO2 and NH3 indoors. Their emission rates may be influenced by human physiological and psychological status. This study investigated the impact of physiological and psychological engagements on the human emissions of CO2 and NH3. In a climate chamber, we measured CO2 and NH3 emissions from participants performing p...

In order to refine the CFD methodology for predicting particle fate in duct flows, this study investigated four key issues largely influencing the predictive accuracy. The flow field modeling method applicable to in-duct UVGI systems (ID-UVs) was also investigated. The particle number independence test indicated that at least 30000 particles should...

As an alternative to Polysomnography (PSG), Fitbit Alta HR (Fitbit) could provide an easier way to monitor sleep. Since the accuracy of Fitbit sleep monitoring is unknown, this study was conducted to compare the sleep monitoring performance of Fitbit and PSG. Nine healthy young adults (5 males and 4 females; 24 ± 2 years old; Pittsburgh Sleep Quali...

Airtight energy-efficient buildings of today need efficient ventilation to secure high indoor air quality. There is a need for affordable and reliable sensors to make demand control available in a broad range of ventilation systems. Low-cost metal oxide semiconductor (MOS) volatile organic compound (VOC) sensors offer such a possibility, but they a...

Proton transfer reaction-mass spectrometry (PTR-MS) has been widely used for monitoring outdoor and indoor volatile organic compounds. For outdoor air, mass-to-charge-ratio m/z 69.07 is usually assigned to isoprene. Isoprene is also a major component of human breath and therefore abundant in occupied indoor environments. Mass 69.07 as an indicator...

Chemical analysis of the composition of indoor air characterizes exposures, but sometimes this analysis may be insufficient to describe the effects of these expo�sures on building occupants, especially to characterize sensory effects caused by exposures to pollutants in buildings. The present chapter presents the methods used to characterize these...

In developed nations, 2/3 of the population fail to obtain the recommended 7-9 hours of sleep, with large consequences for health and productivity. A potent stimulus in regulating sleep and wake balance is light received at a light-sensitive retinal protein called melanopsin, found in our retinal cells, otherwise known as intrinsically retinal gang...

This experimental study aims to test thermal response and the ability to acclimatize during thermal discomfort conditions of different age groups. Experiments were conducted in late summer with thirteen participants, including university students and older workers, exposed in a climate chamber to a temperature increasing from 22°C to 28°C and decre...

The ongoing project 'Bedroom Ventilation and Sleep Quality' investigates the effects of bedroom ventilation on sleep quality and next-day cognitive performance. As part of the project, 84 bedrooms in the Greater Copenhagen area of Denmark were inspected during the 2020 heating season. In the first week, participants slept under environmental condit...

A four-week-long field intervention experiment was conducted in twenty-nine bedrooms with extract ventilation systems and air inlet vents. During the first week no interventions took place. In the three weeks that followed, each participant slept for one week under a low, medium, and high ventilation rate condition in a balanced order. These condit...

This study explored the relationship between children's subjective perception of indoor environmental quality in classrooms, measured thermal and air quality factors, and the type of ventilation. Environmental data were collected in 45 classrooms in 23 primary schools in Sweden during the heating season. Schools with three types of ventilation were...

Bioaerosols are emitted from various sources into the indoor environment and can positively and negatively impact human health. Humans are the major source of bioaerosol emissions indoors, specifically for bacteria. However, efficient sampling to guarantee successful downstream analyses can be challenging due to the relatively low bioaerosol concen...

Humans emit carbon dioxide (CO2) as a product of their metabolism. No measurements of CO2 emission rates (CERs) of elderly sleeping people have yet been reported. This study performed such measurements and examined the possible mechanisms impacting CERs. Sixteen participants (8 males) aged ≥65 years old slept alone for a whole night under each of t...

This study monitored indoor environmental data in 144 classrooms in 31 schools in the Midwestern United States for two consecutive days every fall, winter, and spring during a two-year period; 3,105 pupils attended classrooms where the measurements were conducted. All classrooms were ventilated with mechanical systems that had recirculation; there...

Objectives: To investigate the effect of CO2 during sleep on next-morning cognitive performance in young schoolchildren, the authors performed a double-blind fully balanced crossover placebo-controlled study. Material and methods: The authors included 36 children aged 10-12 years in the climate chamber. The children slept at 21°C in 6 groups eac...

This is an account that should be heard of an important struggle: the struggle of a large group of experts who came together at the beginning of the Covid-19 pandemic to warn the world about the risk of airborne transmission and the consequences of ignoring it. We alerted the World Health Organization (WHO) about the potential significance of the a...

As attention to indoor environmental quality (IEQ) grows, a systematic strategy for assessing IEQ in schools needs to be developed. For this purpose, this paper presents a summary of parameters measured in school classrooms to characterize the quality of thermal, acoustic, and visual environments and indoor air quality (IAQ). The summary is based o...

Predictive models for airborne infection risk have been extensively used during the pandemic, but there is yet still no consensus on a common approach, which may create misinterpretation of results among public health experts and engineers designing building ventilation. In this study we applied the latest data on viral load, aerosol droplet sizes...

Chemical analysis of the composition of indoor air characterizes exposures but sometimes this analysis may be insufficient to describe the effects of these exposures on building occupants, especially sensory effects caused by exposures to pollutants in buildings. The present chapter describes the methods used to characterize these effects. The meth...

Despite notable scientific and medical advances, broader political, socioeconomic and behavioural factors continue to undercut the response to the COVID-19 pandemic1,2. Here we convened, as part of this Delphi study, a diverse, multidisciplinary panel of 386 academic, health, non-governmental organization, government and other experts in COVID-19 r...

Despite notable scientific and medical advances, broader political, socioeconomic and behavioural factors continue to undercut the response to the COVID-19 pandemic 1,2 . Here we convened, as part of this Delphi study, a diverse, multidisciplinary panel of 386 academic, health, non-governmental organization, government and other experts in COVID-19...

Despite notable scientific and medical advances, broader political, socioeconomic and behavioural factors continue to undercut the response to the COVID-19 pandemic1,2. Here we convened, as part of this Delphi study, a diverse, multidisciplinary panel of 386 academic, health, non-governmental organization, government and other experts in COVID-19 r...

Despite notable scientific and medical advances, broader political, socioeconomic and behavioural factors continue to undercut the response to the COVID-19 pandemic 1,2 . Here we convened, as part of this Delphi study, a diverse, multidisciplinary panel of 386 academic, health, non-governmental organization, government and other experts in COVID-19...

We present a method that can be used to optimize CFD analyses of ventilation performance in buildings; the method was successfully applied in other disciplines. In the method, three statistical methods are used - the Taguchi method, ANOVA, and Grey Relational Analysis (GRA) to achieve optimization. We then model the risk of draft and the mean age o...

Indoor Air Quality (IAQ) and sleep quality measurements over a period of two weeks were performed all night in 40 bedrooms in Denmark during the heating season. In the first week, the bedroom conditions were typical of what participants would normally experience during sleep. In the second week, the participants were asked to open the doors or wind...

Background Aircraft cabins are special environments. Passengers sit in close proximity in a space with low pressure that they cannot leave. The cabin is ventilated with a mixture of outside and recirculated air. The volume of outside air impacts the carbon footprint of flying. Higher recirculation air rates could be considered to save energy and di...

The present study aimed at investigating the effects of ventilation strategies on indoor air quality (IAQ) in schools. Measurements of thermal environment and IAQ were performed over 5 school days in 45 primary school classrooms in Gothenburg, Sweden, grouped into three categories according to their ventilation system: category A) natural or exhaus...

Hydroxyl (OH) radicals are highly reactive species that can oxidize most pollutant gases. In this study, high concentrations of OH radicals were found when people were exposed to ozone in a climate-controlled chamber. OH concentrations calculated by two methods using measurements of total OH reactivity, speciated alkenes, and oxidation products wer...

Parameters describing the bedroom environment and sleep quality were measured overnight for one week in 84 randomly selected actual bedrooms in Denmark from September to December 2020. The median age of participants was 26 years (interquartile range (IQR) (Laverge et al., 2015; Fan et al., 2021; Berglund et al., 1999; Zhang et al., 2016; Bjorvatn e...

Ventilation systems are a vital component of buildings in order to ensure a healthy and comfortable environment for the occupants. In cold climate regions, ventilation systems are responsible for approximately 30% of building heat losses. In addition to outdoor pollutants (particulate matters, NOX, etc.), indoor emissions from materials in the form...

Background In previous studies, negative associations were found between increased environmental sensitivity and general well-being as well as positive perception of air quality. However, only a few studies with partly inconsistent results examined this relation under exposure. They tried to determine whether people with increased environmental sen...

Accurate prediction of inhaled CO2 concentration and alveolar gas exchange efficiency would improve the prediction of CO2 concentrations around the human body, which is essential for advanced ventilation design in buildings. We therefore, developed a computer‐simulated person (CSP) that included a computational fluid dynamics approach. The CSP simu...

The question of whether SARS‐CoV‐2 is mainly transmitted by droplets or aerosols has been highly controversial. We sought to explain this controversy through a historical analysis of transmission research in other diseases. For most of human history, the dominant paradigm was that many diseases were carried by the air, often over long distances and...

We explored the importance of inhaled air temperature on thermal comfort, perceived air quality, acute non‐clinical health symptoms, and physiological responses. Sixteen subjects stayed in a stainless‐steel chamber for 90 min. They experienced four conditions with two inhaled air temperatures of 22 and 30°C and two ambient temperatures of 22 and 30...

A widely used analytical model to quantitatively assess airborne infection risk is the Wells-Riley model which is limited to complete air mixing in a single zone. However, this assumption tends not to be feasible (or reality) for many situations. This study aimed to extend the Wells-Riley model so that the infection risk can be calculated in spaces...

With a modified version of the Wells-Riley model, we simulated the size distribution and dynamics of five airborne viruses (measles, influenza, SARS-CoV-2, human rhinovirus, and adenovirus) emitted from a speaking person in a typical residential setting over a relative humidity (RH) range of 20–80% and air temperature of 20–25 °C. Besides the size...

Several research studies have ranked indoor pollution among the top environmental risks to public health in recent years. Good indoor air quality is an essential component of a healthy indoor environment and significantly affects human health and well-being. Poor air quality in such environments may cause respiratory disease for millions of pupils...

Human-emitted volatile organic compounds (VOCs) are mainly from breath and the skin. In this study, we continuously measured VOCs in a stainless-steel environmentally controlled climate chamber (22.5 m3, air change rate at 3.2 h-1) occupied by four seated human volunteers using proton transfer reaction time-of-flight mass spectrometry and gas chrom...

Carbon dioxide (CO2) and methane (CH4) are important greenhouse gases in the atmosphere and have large impacts on Earth's radiative forcing and climate. Their natural and anthropogenic emissions have often been in focus, while the role of human metabolic emissions has received less attention. In this study, exhaled, dermal and whole-body CO2 and CH...

With a modified version of the Wells-Riley model, we simulated the size distribution and dynamics of five airborne viruses (measles, influenza, SARS-CoV-2, human rhinovirus, and adenovirus) emitted from a speaking person in a typical residential setting over a relative humidity (RH) range of 20 to 80 % and air temperature of 20-25 °C. Besides the s...

Abstract Indoor air quality (IAQ) affects the quality of life by increasing the risks for health problems and reduced work performance. Consequently, different societal costs are incurred. By reducing pollutants elevating exposures indoors, and improving IAQ, these costs can be reduced or avoided. This chapter attempts to summarize the evidence and...

The breathing zone of an individual indoors is usually defined as a finite region steadily formed in front of a face. Assuming the steady formation of the breathing zone, we propose a procedure for quantitatively identifying a breathing zone formed in front of a human face in the transient condition. This assumption is reasonable considering that t...

Wrist skin temperature has been validated to be sensitive to the thermal state of awake people, but its correlation with thermal state of sleeping people has not been investigated. In the present study four human subject experiments were performed on both young and elderly subjects in different seasons (winter, transition, summer). Their skin tempe...

The recently developed TAIL rating scheme enables assessment of the changes in the indoor environmental quality (IEQ) associated with a building’s deep energy renovation (DER) and classification of the resulting quality levels of the thermal (T), acoustic (A), and luminous (visual) (L) environments and indoor air quality (I). Since the TAIL rating...

Ten healthy young adults slept one by one in a specially designed and constructed sleep capsule located in a climate chamber at two temperatures (24 and 28 °C) and two ventilation rates that ensured that the resulting CO2 concentrations were 800 and 1700 ppm. Subjectively rated sleep quality was reduced at 28 °C and reduced ventilation, while sleep...

We determined carbon dioxide (CO2) emission rates from sedentary subjects performing light work on tablets or smartphones in controlled chamber exposures. Five groups, each consisting of four people (four groups with two females and two males and one with three males and one female), stayed in a 22.5 m³ stainless steel chamber under different envir...

Although indoor environmental quality (IEQ) and human health have been on the agenda of the green building industry, a new emphasis is being placed on building features that explicitly promote the experience of occupants. However, evidence of the performance of green-certified buildings from the occupant perspective remains inconsistent, with numer...

Sleep is essential for the health of elderly people, but few studies have made connection between their sleep quality and their bedroom environment. This study performed field measurements in Shanghai, China, to investigate the bedroom thermal environment and ventilation and their associations with the sleep quality of elderly subjects in summer. F...

Poor air quality has been shown to reduce sleep quality. There is a limited number of studies reporting how occupants rate the air quality in their bedrooms. The present study sheds the light on this issue. It was conducted in actual bedrooms and asked occupants to rate air quality once awake in the morning using an online sleep diary. The study wa...

Cement is the second most consumed substance by weight in the world, after water. The growing demand for reduced emissions of CO 2 urges the cement industry to find materials with a low CO 2 footprint, which calls for cement substitution. An assumption of the study has been that sewage sludge ash (SSA), an industrial by-product, can be applied as a...

Nanocluster aerosols (NCAs, particles <3 nm) are important players in driving climate feedbacks and processes that impact human health. This study reports, for the first time, NCA formation when gas-phase ozone reacts with human surfaces. In an occupied climate-controlled chamber, we detected NCA only when ozone was present. NCA emissions were depe...

The relation between electroencephalogram signals, thermal comfort, and cognitive performance in neutral to hot indoor environment was investigated. The experiments were carried out at four temperatures: 26ºC, 30ºC, 33ºC, and 37ºC, and two relative humidity levels: 50% and 70%. Thirty-two subjects were exposed for 175 min. The electroencephalogram...

Hvordan bør vi indrette vores boliger, kontorer og bygninger i fremtiden, så de bliver mere robuste ift. COVID-19 og kommende pandemier? Det har medicinere fra bl.a. Statens Seruminstitut, ventilationsteknikere og arkitekter sat sig for at undersøge. (How should we design our homes, offices and buildings in the future so that they become more robus...

People influence indoor air chemistry through their chemical emissions via breath and skin. Previous studies showed that direct measurement of total OH reactivity of human emissions matched that calculated from parallel measurements of volatile organic compounds (VOCs) from breath, skin, and the whole body. In this study, we determined, with direct...

A new design method is proposed to calculate outdoor air ventilation rates to control respiratory infection risk in indoor spaces. We propose to use this method in future ventilation standards to complement existing ventilation criteria based on the perceived air quality and pollutant removal. The proposed method makes it possible to calculate the...