The benefits of whole-house in-duct air cleaning in reducing exposures to fine particulate matter of outdoor origin: A modeling analysis

Abstract

Health risks of fine particle air pollution (PM 2.5 ) are an important public health concern that has the potential to be mitigated in part by interventions such as air cleaning devices that reduce personal exposure to ambient PM 2.5 . To characterize exposure to ambient PM 2.5 indoors as a function of residential air cleaners, a multi-zone indoor air quality model was used to integrate spatially resolved data on housing, meteorology, and ambient PM 2.5 , with performance testing of residential air cleaners to estimate short-term and annual average PM 2.5 of outdoor origin inside residences of three metropolitan areas. The associated public health impacts of reduced ambient PM 2.5 exposure were estimated using a standard health impact assessment methodology. Estimated indoor levels of ambient PM 2.5 varied substantially among ventilation and air cleaning configurations. The median 24-h average indooroutdoor ratio of ambient PM 2.5 was 0.57 for homes with natural ventilation, 0.35 for homes with central air conditioning (AC) with conventional filtration, and 0.1 for homes with central AC with high efficiency in-duct air cleaner. Median modeled 24-h average indoor concentrations of PM 2.5 of outdoor origin for those three configurations were 8.4, 5.3, and 1.5 mg/m 3 , respectively. The potential public health benefits of reduced exposure to ambient PM 2.5 afforded by air cleaning systems were substantial. If the entire population of single-family homes with central AC in the modeling domain converted from conventional filtration to high-efficiency in-duct air cleaning, the change in ambient PM 2.5 exposure is estimated to result in an annual reduction of 700 premature deaths, 940 hospital and emergency room visits, and 130,000 asthma attacks in these metropolitan areas. In addition to controlling emissions from sources, high-efficiency whole-house air cleaner are expected to reduce exposure to particles of outdoor origin and are projected to be an effective means of managing public health impacts of ambient particle pollution.

Indoor air quality in 24 California residences designed as high-performance homes

“…Homes that failed to provide active filtration generally used radiant or point-source gas or gas heating, in lieu of a central forced air system, and they did not have filtered ventilation systems. Our findings are consistent with field measurements and simulation efforts that have shown filtration to provide health benefits through lower indoor particle concentrations (Burroughs and Kinzer, 1998;MacIntosh et al, 2009). Due to their dominance of the health effects of chronic pollutant exposure in homes (Logue et al, 2010), controlling particle levels should be a primary goal of any high performance green home.…”

Comparison of Test Methods for Determining the Particle Removal Efficiency of Filters in Residential and Light-Commercial Central HVAC Systems

“…Typical fractional operation times of residential and lightcommercial air-conditioning systems have ranged from 6% to 60%, depending on building and system characteristics, climate, and time of day (James et al 1997;Thornburg et al 2004;Stephens et al 2011). Thus, both HVAC operational characteristics and filter selection are important factors in determining particle fates in these environments (MacIntosh et al 2010) and should be measured in any field study of central HVAC filtration.…”

Assessing exposure to granite countertops—part 2: Radon

“…The CONTAM multi-zone indoor air quality model (Walton and Dols, 2003) developed by the National Institute of Standards and Technology (NIST) was used to estimate indoor radon concentrations following a previously published methodology (Myatt et al, 2008;MacIntosh et al, 2009). Briefly, airflow among indoor and outdoor zones of the building (that is, rooms and ambient air) in CONTAM occurs through flow paths such as doors, windows, and cracks.…”