Spatially resolved intake fraction estimates for primary and secondary particulate matter in the United States

Publication date: February 2017
Source:Atmospheric Environment, Volume 150
Author(s): Carmen Lamancusa, Fatema Parvez, Kristina Wagstrom
This study uses intake fraction, the fraction of emissions that are inhaled from a given source, to quantify how emissions from different regions proportionally contribute to human exposure to both primary and secondary particulate matter species. The intake fraction for secondary species is defined using the common atomic constituents between precursor species and products, allowing estimates to include both primary and secondary species. The Particulate Matter Source Apportionment Technology (PSAT) in the Comprehensive Air Quality Model with Extensions (CAMx) regional air quality model is used to calculate the intake fraction for twenty-five source regions throughout the contiguous United States over four seasons. The calculations use spatially explicit emissions and population density to more accurately capture the variation in intake fraction between regions. The spatially explicit emissions allow for the calculation of spatial trends and variations within the intake fraction. More specifically it allows for the calculation of the amount of intake that occurs within a given distance of the emissions source or source region. Based on the results sulfate inhalation occurs over larger distances than other particulate matter species. For most regions, a substantial fraction (>75%) of the inhalation occurs within 50 km for all seasons, demonstrating that efforts to reduce emissions will have the largest health impact on the local community. Furthermore the distance over which 75% of the inhalation occurs increases by 20% for all species during the winter and a larger percentage of pollutants emitted during the winter are inhaled relative to pollutants emitted during other seasons. This demonstrates that emission reductions during the winter will have a greater impact on health than reductions during other seasons.

Graphical abstract

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