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VENTILATION AND INDOOR AIR QUALITY IN NEW HOMES
Abstract
Concerns have been raised regarding whether homeowners use windows, exhaust fans, and other mechanical ventilation devices enough to remove indoor air contaminants and excess moisture. In a multi-season study of ventilation and indoor air quality of 108 new single-family, detached homes in California, window use, ventilation rates, and air contaminant concentrations were measured. The median 24-hour outdoor air exchange rate was 0.26 air changes per hour; 67 percent of the homes were below the California building code requirement of 0.35 air changes per hour; and 32 percent of the homes did not use their windows. Home-to-garage pressure testing guidelines were exceeded in 65 percent of the homes. The median indoor formaldehyde concentration was 36 micrograms per cubic meter (range of 4.8 to 136 micrograms per cubic meter). Nearly all homes had formaldehyde concentrations that exceeded guidelines for cancer and chronic irritation, while 59 percent exceeded guidelines for acute irritation. In conclusion, new single-family detached homes in California are built relatively airtight, can have very low outdoor air exchange rates, and can often exceed exposure guidelines for air contaminants with indoor sources, such as formaldehyde and some other volatile organic compounds. Mechanical ventilation systems are needed to provide a dependable, continuous supply of outdoor air to new homes, and reductions of various indoor formaldehyde sources are also needed.
... However, the formaldehyde concentration in the chamber increased from 0.5 ppb v (0.6 μg m −3 ) the day before the tree was placed in the chamber to 3.1 ppb v (3.9 μg m −3 ) when the tree was present prior to the ozone being injected on Day 2. This 2.6 ppb v (3.2 μg m −3 ) increase in formaldehyde concentration when the tree was placed in the chamber is the maximum concentration increase due to initial primary emissions for this tree (the researcher setting up the tree in the stand could have contributed to this value). For context, typical indoor formaldehyde concentrations in 105 new homes which on average had air change rates of one half of this study (0.26 h −1 compared to 0.57 h −1 here) is 29 ppb v (36 μg m −3 )[44]. ...
Every year in the United States conifers are purchased to serve as Christmas trees in homes where they emit volatile organic compounds (VOCs) to the indoor environment. Although many studies have measured the ecosystem-level emissions of VOCs from conifers outdoors (characterizing monoterpene, isoprene, and aldehyde emissions), little is known about VOC emission rates once a conifer is brought indoors. Using a proton transfer reaction-mass spectrometer we characterized the VOCs emitted from a freshly cut Douglas Fir for 17 days in an environmentally controlled chamber. Ozone injections were also performed to analyze indoor chemistry that may occur. Introduction of the tree into the chamber increased the response of 52 mass spectra signals detected by the PTR-MS by at least 500 counts per second (cps) compared to background levels, with concentrations sharply decreasing after the first two days. Monoterpenes were emitted from the tree at a rate of 12.4 mg h⁻¹ the first day and fell to 1 mg h⁻¹ by day three. Overall, monoterpene emissions from this Douglas fir were initially comparable to other strong indoor monoterpene sources (fragranced products and air fresheners) but decayed quickly and, within days, were smaller than other common indoor sources. Addition of ozone to the chamber resulted in decreased monoterpene concentrations that coincided with modest increases in formaldehyde. Four other emitted VOCs were tentatively identified due to their large increase within the first few hours of the tree placed in the chamber, behavior during ozonation, or pattern of accumulation over time.
... 24 The study in California investigated 24 VOCs in 108 newly-built homes and found that formaldehyde concentrations were affected by ventilation type and geographical location of the dwellings. 25 Similar conclusions were drawn in the measurement campaign in 305 dwellings in Sweden. 26 The French Observatory for Indoor Air Quality (IOAQ) measured VOCs in 567 French homes, in which the influence of building characteristics and socioeconomic factors on VOCs was analyzed. ...
Exposure to elevated levels of certain volatile organic compounds (VOCs) in households has been linked to deleterious health effects. This study presents the first large‐scale investigation of VOC levels in 169 energy‐efficient dwellings in Switzerland. Through a combination of physical measurements and questionnaire surveys, we investigated the influence of diverse building characteristics on indoor VOCs. Among 74 detected compounds, carbonyls, alkanes and alkenes were the most abundant. Median concentration levels of formaldehyde (14 μg/m3), TVOC (212 μg/m3), benzene (< 0.1 μg/m3) and toluene (22 μg/m3) were below the upper exposure limits. Nonetheless, 90% and 50% of dwellings exceeded the chronic exposure limits for formaldehyde (9 μg/m3) and TVOC (200 μg/m3) respectively. There was a strong positive correlation among VOCs that likely originated from common sources. Dwellings built between 1950s and 1990s, and especially those with attached garages had higher TVOC concentrations. Interior thermal retrofit of dwellings and absence of mechanical ventilation system were associated with elevated levels of formaldehyde, aromatics and alkanes. Overall, energy‐renovated homes had higher levels of certain VOCs compared to newly built homes. The results suggest that energy‐efficiency measures in dwellings should be accompanied with actions to mitigate VOC exposures as to avoid adverse health outcomes.
... • Where concentrations of formaldehyde significantly increased as the air change rate fell below 0.5 ACHnat (see Figure 1) when there was no mechanical assistance in a US survey by Offermann (2009). Nearly all houses in this survey failed a 9 µg/m 3 8hour Reference Exposure Level for formaldehyde (Offermann 2009, 5-6). ...
... 22 Despite these regulations, formaldehyde levels exceeded guidelines for chronic and acute respiratory irritations and cancer risks in most California homes tested in a 2007-2008 study. 23 Why? ...
There is no question that investing in energy-efficiency upgrades has the potential to deliver substantial financial, environmental, and health benefits to building owners and residents. Robust evidence demonstrates that interventions such as weatherization and other energy-efficiency upgrades, particularly in poor quality housing, can significantly improve residents’ health by reducing thermal stress, asthma symptoms, and energy
costs. What is far less understood and addressed, however, are the adverse health impacts produced by chemical emissions from some of the materials commonly used for these upgrades. These materials often contain persistent, bioaccumulative, or
toxic chemicalsb and either show evidence or are suspected of being asthmagens, reproductive or developmental toxicants, endocrine disruptors, or carcinogens. Not only are a building’s residents endangered, but these chemicals of concern can also pose threats over the materials’ life cycles to the workers who manufacture, install, and dispose of these products, to the communities adjacent to these facilities, and to the broader environment. Many of these populations are some of our most vulnerable and have limited access to health care.
This guide includes research on the common chemical content and associated health hazards for a range of insulation and sealant materials as well as simple, actionable recommendations to make the best material choices possible. Because hazardous content is not the only consideration when making material choices, also included is a compilation of relative cost information, performance characteristics, and installation and code considerations. Finally, the report introduces a discussion of policies that may impact material decisions and how to encourage the use of healthier materials in multifamily energy efficiency upgrades.
... In response to changes in building codes, recent studies have evaluated the energy use and other performance aspects of new US homes [6][7][8]. These studies suggest a general trend that new homes are being built tighter in some parts of the US. ...
This study characterized emissions from IQOS, a heated tobacco product promoted as a less harmful alternative to cigarettes. Consumable tobacco plugs were analyzed by headspace GC/MS to assess the influence of heating temperature on the emission profile. Yields of major chemical constituents increased from 4.1 mg per unit at 180 °C to 6.2 mg at 200 °C, and 10.5 mg at 220 °C. The Health Canada Intense smoking regime was used to operate IQOS in an environmental chamber, quantifying 33 volatile organic compounds in mainstream and sidestream emissions. Aldehydes, nitrogenated and aromatic species were found, along with other harmful and potentially harmful compounds. Compared with combustion cigarettes, IQOS yields were in most cases 1-2 orders of magnitude lower. However, yields were closer to, and sometimes higher than electronic cigarettes. Predicted users’ daily average intake of benzene, formaldehyde, acetaldehyde and acrolein were 39 µg, 32 µg, 2.2 mg and 71 µg, respectively. Indoor air concentrations were estimated for commonly encountered scenarios, with acrolein levels of concern (over 0.35 µg m-3) derived from IQOS used in homes and public spaces. Heated tobacco products are a weaker indoor pollution source than conventional cigarettes, but their impacts are neither negligible nor yet fully understood.
Background
Microorganisms influence the chemical milieu of their environment, and chemical metabolites can affect ecological processes. In built environments, where people spend the majority of their time, very little is known about how surface-borne microorganisms influence the chemistry of the indoor spaces. Here, we applied multidisciplinary approaches to investigate aspects of chemical microbiology in a house. Methods
We characterized the microbial and chemical composition of two common and frequently wet surfaces in a residential setting: kitchen sink and bathroom shower. Microbial communities were studied using culture-dependent and independent techniques, including targeting RNA for amplicon sequencing. Volatile and soluble chemicals from paired samples were analyzed using state-of-the-art techniques to explore the links between the observed microbiota and chemical exudates. ResultsMicrobial analysis revealed a rich biological presence on the surfaces exposed in kitchen sinks and bathroom shower stalls. Microbial composition, matched for DNA and RNA targets, varied by surface type and sampling period. Bacteria were found to have an average of 25× more gene copies than fungi. Biomass estimates based on qPCR were well correlated with measured total volatile organic compound (VOC) emissions. Abundant VOCs included products associated with fatty acid production. Molecular networking revealed a diversity of surface-borne compounds that likely originate from microbes and from household products. Conclusions
Microbes played a role in structuring the chemical profiles on and emitted from kitchen sinks and shower stalls. Microbial VOCs (mVOCs) were predominately associated with the processing of fatty acids. The mVOC composition may be more stable than that of microbial communities, which can show temporal and spatial variation in their responses to changing environmental conditions. The mVOC output from microbial metabolism on kitchen sinks and bathroom showers should be apparent through careful measurement, even against a broader background of VOCs in homes, some of which may originate from microbes in other locations within the home. A deeper understanding of the chemical interactions between microbes on household surfaces will require experimentation under relevant environmental conditions, with a finer temporal resolution, to build on the observational study results presented here.
A multi-season field study of ventilation and indoor air quality (IAQ) was conducted in 108 new single-family, detached homes in California, to study the elevated concentrations of indoor air contaminants with indoor sources in airtight homes with closed windows. In the study, outdoor air ventilation rates were determined concurrent with the air contaminant measurements using passive perfluorocarbon tracer (PFT) gas measurements. The results show that of the indoor air contaminants measured, only formaldehyde and particulate matter exceeded recommended non-cancer and non-reproductive exposure guidelines. For carbon dioxide, the indoor concentrations exceeded the ASHRAE Standard 62.1 body odor guideline of 700 ppm over outdoors for 9.4 hours per day, with no exceedences for a continuous system. It is recommended that airtight energy-efficient homes be provided with mechanical outdoor ventilation that is at least that prescribed by Standard 62.2. For a 1,764 ft 2.
The need to reduce carbon emissions and fuel poverty has led to increased building envelope air tightness, intended to reduce uncontrolled ventilation heat losses. Ventilation strategies in dwellings still allow the use of trickle ventilators in window frames for background ventilation. The extent to which this results in “healthy” Indoor Air Quality (IAQ) in recently constructed dwellings was a concern of regulators in Scotland. This paper describes research to explore this. First a review of literature was conducted, then data on occupant interactions with ventilation provisions (windows, doors, trickle vents) gathered through an interview-based survey of 200 recently constructed dwellings, and measurements made on a sample of 40 of these. The main measured parameter discussed here is CO2 concentration. It was concluded after the literature review that 1000 ppm absolute was a reasonable threshold to use for “adequate” ventilation. The occupant survey found that there was very little occupant interaction with the trickle ventilators e.g., in bedrooms 63% were always closed, 28% always open, and in only 9% of cases occupants intervened to make occasional adjustments. In the measured dwellings average bedroom CO2 levels of 1520 ppm during occupied (night time) hours were observed. Where windows were open the average bedroom CO2 levels were 972 ppm. With windows closed, the combination of “trickle ventilators open plus doors open” gave an average of 1021 ppm. “Trickle ventilators open” gave an average of 1571 ppm. All other combinations gave averages of 1550 to 2000 ppm. Ventilation rates and air change rates were estimated from measured CO2 levels, for all dwellings calculated ventilation rate was less than 8 L/s/p, in 42% of cases calculated air change rate was less than 0.5 ach. It was concluded that trickle ventilation as installed and used is ineffective in meeting desired ventilation rates, evidenced by high CO2 levels reported across the sampled dwellings. Potential implications of the results are discussed.
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