AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Modeling Urban Intake Fraction Gradients Using the InMAP Model
SARAH CHAMBLISS, Christopher Tessum, Julian Marshall, Joshua Apte, University of Texas at Austin
Abstract Number: 640 Working Group: Urban Aerosols
Abstract A major challenge in alleviating the health burden of urban air pollution is identifying which emission sources cause the most exposure. The exposure to fine particulate matter (PM2.5) resulting from an emissions source depends not only on the total mass of primary PM2.5 and aerosol precursor gases emitted, but also on the source’s location relative to city residents and regional atmospheric conditions that affect secondary PM2.5 formation. These additional factors are reflected in a source’s intake fraction, or the ratio of mass inhaled (as PM2.5) to mass emitted. Mechanistic models have been used to predict and compare intake fractions of various emissions sources, but these models are often run at a resolution too coarse to identify urban-scale variation or are only run for a single urban area. We use a source-receptor matrix created using the Intervention Model for Air Pollution (InMAP) with variable grid size, allowing up to 1-km resolution modeling of primary and secondary PM2.5 intake fractions for all urban areas within the continental United States. This model shows that the locality of emissions within a city greatly affects the resulting exposure. Centrally-located emissions of primary PM2.5 result in up to 25 times more exposure than emissions at the urban periphery. For emissions of nitrogen oxides (NOX) and secondary organic aerosol (SOA), location causes up to a tenfold variation in secondary PM2.5 exposure. Intake fractions are highest in the largest cities. Comparing mean intake fractions, a ton of primary PM2.5 emitted in a city with a population >3 million (n=14) would result in ten times the exposure as the same emissions in a city with a population <100,000. For secondary PM2.5 from NOX and SOA, mean intake fractions are higher in large cities by a factor of 2 and 4, respectively.