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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.
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... Traditionally, open windows have made important contributions to residential ventilation, so simply having a tighter envelope does not necessarily translate to lower air-exchange rates. However, recent measurements of ventilation rates in new single-family dwellings in California indicate that low rates are common in that portion of the building stock: 67% of 108 homes monitored had ventilation rates lower than the California building code requirement of 0.35 air changes per hour (Offermann 2009). Lower air-exchange rates would tend to provide improved protection for building occupants against particles of outdoor origin. ...
... A transition is underway in the US housing stock toward more widespread use of mechanical systems to provide ventilation , Offermann 2009, Sherman and Walker 2011. Mechanical systems that provide supply air can be equipped with filters to remove particles. ...
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Climate change will affect the concentrations of air pollutants in buildings. The resulting shifts in human exposure may influence public health. Changes can be anticipated because of altered outdoor pollution and also owing to changes in buildings effected in response to changing climate. Three classes of factors govern indoor pollutant levels in occupied spaces: (a) properties of pollutants; (b) building factors, such as the ventilation rate; and (c) occupant behavior. Diversity of indoor conditions influences the public health significance of climate change. Potentially vulnerable subpopulations include not only the young and the infirm but also those who lack resources to respond effectively to changing conditions. Indoor air pollutant levels reflect the sum of contributions from indoor sources and from outdoor pollutants that enter with ventilation air. Pollutant classes with important indoor sources include the byproducts of combustion, radon, and volatile and semivolatile organic compounds. Outdoor pollutants of special concern include particulate matter and ozone. To ensure good indoor air quality it is important first to avoid high indoor emission rates for all pollutants and second to ensure adequate ventilation. A third factor is the use of air filtration or air cleaning to achieve further improvements where warranted.
... 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. ...
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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? ...
Technical Report
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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.
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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.
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