An assessment of Aviation’s contribution to current and future fine particulate matter in the United States

Abstract

The impacts of aviation emissions on current and future year fine particulate matter (PM 2.5 ) were investigated using the Community Multiscale Air Quality model, accounting for aviation emissions from 99 airports and below 3 km during landing and takeoff (LTO) cycles. Results indicated that current year aviation emissions increased annual average PM 2.5 concentrations by 3.2 ng m −3 (0.05%) in the continental U.S. while projected 2025 aviation emissions increased annual average PM 2.5 by 11.2 ng m −3 (0.20%). Ammonium nitrate aerosol was the largest contributor to the increase in PM 2.5 concentrations, particularly in the future year. Using an indicator of inorganic PM 2.5 change, we attributed ammonium nitrate aerosol contributions in both years to excess free ammonia (8% higher NH 3 and 35% lower NO x emissions from non-aviation sources in 2025 than 2005), and higher aircraft emissions of NO x (which when converted to HNO 3 forms ammonium nitrate aerosol) than SO 2 (a precursor of ammonium sulfate aerosol). Our findings highlight the critical role that non-aviation emissions play in assessing the air quality impacts of aviation emissions in a future year scenario. ► Aircraft LTO emissions in U.S. contribute 3.2 ng/m 3 or 0.05% of annual PM 2.5 in 2005. ► This contribution increases four fold to 0.20% for a future year scenario in 2025. ► Nitrate aerosol was the largest contributor to the changes in PM 2.5. ► Non-aviation emissions combined with aircraft NO x impact future year concentrations. ► Free Ammonia explains the role of non-aviation sources in forming ammonium nitrate.