Abstract
Air pollution epidemiology studies of ambient fine particulate matter (PM2.5) and ozone (O3) often use outdoor concentrations as exposure surrogates. Failure to account for the variability of the indoor infiltration of ambient PM2.5 and O3, and time indoors, can induce exposure errors. We developed an exposure model called TracMyAir, which is an iPhone application (“app”) that determines seven tiers of individual-level exposure metrics in real-time for ambient PM2.5 and O3 using outdoor concentrations, weather, home building characteristics, time-locations, and time-activities. We linked a mechanistic air exchange rate (AER) model, a mass-balance PM2.5 and O3 building infiltration model, and an inhaled ventilation model to determine outdoor concentrations (Tier 1), residential AER (Tier 2), infiltration factors (Tier 3), indoor concentrations (Tier 4), personal exposure factors (Tier 5), personal exposures (Tier 6), and inhaled doses (Tier 7). Using the application in central North Carolina, we demonstrated its ability to automatically obtain real-time input data from the nearest air monitors and weather stations, and predict the exposure metrics. A sensitivity analysis showed that the modeled exposure metrics can vary substantially with changes in seasonal indoor-outdoor temperature differences, daily home operating conditions (i.e., opening windows and operating air cleaners), and time spent outdoors. The capability of TracMyAir could help reduce uncertainty of ambient PM2.5 and O3 exposure metrics used in epidemiology studies.
Highlights
Epidemiological studies have found associations between exposure to ambient fine particulate matter (PM2.5 ; particulate matter ≤2.5 μm in aerodynamic diameter) or ozone (O3 ) and indices of acute cardiopulmonary morbidity and mortality [1,2]
To determine seven tiers of exposure metrics for ambient PM2.5 and O3 (Figure 1), which include measured outdoor concentrations at nearby monitors (Tier 1), three exposure metrics related to PM2.5 and O3 infiltration into homes, (Tier 2: air exchange rate (AER); Tier 3: infiltration factors; Tier 4: indoor concentrations), two exposure metrics that account for time spent in different indoor and outdoor locations (Tier 5: personal exposure factors; Tier 6: exposures), and a metric that accounts for time spent at different intensity levels of physical activity (Tier 7: inhaled dose)
Using TracMyAir, we can perform an individual-level exposure assessment for epidemiological studies that accounts for daily variations in ambient PM2.5 exposures and intake dose based on a mechanistic house-specific AER model linked to a mass-balance PM2.5 and O3 infiltration model, infiltration factors for nonresidential buildings and vehicles, and daily time-location and time-activity data from each participant
Summary
Epidemiological studies have found associations between exposure to ambient (i.e., outdoor-generated) fine particulate matter (PM2.5 ; particulate matter ≤2.5 μm in aerodynamic diameter) or ozone (O3 ) and indices of acute cardiopulmonary morbidity and mortality [1,2]. Most of these studies used outdoor PM2.5 or O3 concentrations as exposure surrogates due to the financial cost and participant burden from wearing personal air pollution measuring devices. Public Health 2019, 16, 3468; doi:10.3390/ijerph16183468 www.mdpi.com/journal/ijerph
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International journal of environmental research and public health
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
