Filter Forensics: A novel method for exploring exposure to particle-bound contaminants

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Canadians spend two-thirds of their time in their homes and are exposed to a variety of contaminants in residential settings. Most of our exposure to air pollution occurs inside of buildings, and particularly in our homes. Despite its importance to human health, the indoor environment is relatively unstudied. The health consequences of indoor particulate matter (PM) exposure are significant and cost the Canadian economy billions of dollars in health care costs. The heating, ventilation, and air conditioning (HVAC) filters present in over 60% of Canadian households represent an untapped opportunity to assess human exposure to particle-bound contaminants. Although there is little scientific and medical doubt of the serious health consequences of exposure to particles, the amount of exposure that occurs indoors and the composition of indoor particles are areas ripe for further exploration. Traditional methods of assessing indoor particles typically rely on either settled dust samples or short-term air samples. Settled dust samples are biased towards contaminants associated with larger particles and are only spatially representative of the room/area from which they are collected. Short-term air samples are typically only collected for periods ranging from minutes to a few hours and thus collect a small volume of air. These traditional sampling approaches capture a snapshot of indoor particle concentrations and do not allow for detailed exposure analysis. Unlike these approaches, HVAC filters are in place for extended periods of time and provide an integrated sample of the airborne particles present in homes and thus provide an exposure-relevant concentration. When coupled with in-situ filter efficiency, runtime, and airflow measurements, analysis of the particles captured by filters offer a novel opportunity to assess the airborne concentrations of particle-bound pollutants in homes. The central objectives of the proposed research are both to explore the validity of this innovative sampling approach by comparing filter measurements from detailed long term testing, as well as explore the utility of this approach if it were used in a forensics context by recovering filters from homes and analyzing the dust on them. The specific contaminants that will be explored include fungi, allergens, black carbon, and heavy metals. The central benefit of the proposed approach is to improve the health of Canadians by understanding our exposure to serious contaminants. An additional benefit of the proposed research is to develop a low-cost approach for rapidly assessing exposure hot spots as well as respond to extraordinary events such as wildfires, industrial accidents, and flooding. This research will result in a transformative understanding of concentrations of indoor particle-bound contaminants.