Modeling future asthma attributable to fine particulate matter (PM) in a changing climate: a health impact assessment.

Exposure to fine particulate matter (PM) is associated with asthma development as well as asthma exacerbation in children. PM can be directly emitted or can form in the atmosphere from pollutant precursors. PM emitted and formed in the atmosphere is influenced by meteorology; future changes in climate may alter the concentration and distribution of PM. Our aim is to estimate the future burden of climate change and PM on new and exacerbated cases of childhood asthma. Projected concentrations of PM are based on the Geophysical Fluid Dynamics Laboratory Coupled Model version 3 climate model, the Representative Concentration Pathway 8.5 greenhouse gas scenario, and two air pollution emissions datasets: a 2011 emissions dataset and a 2040 emissions dataset that reflects substantial reductions in emissions of PM as compared to the 2011 inventory. We estimate additional PM-attributable asthma as well as PM-attributable albuterol inhaler use for four future years (2030, 2050, 2075, and 2095) relative to the year 2000. Exacerbations, regardless of the trigger, are counted as attributable to PM if the incident disease is attributable to PM. We project 38 thousand (95% CI 36, 39 thousand) additional PM-attributable incident childhood asthma cases and 29 million (95% CI 27, 31 million) additional PM-attributable albuterol inhaler uses per year in 2030, increasing to 200 thousand (95% CI 190, 210 thousand) additional incident cases and 160 million (95% CI 150, 160 million) inhaler uses per year by 2095 relative to 2000 under the 2011 emissions dataset. These additional PM-attributable incident asthma cases and albuterol inhaler use would cost billions of additional U.S. dollars per year by the late century. These outcomes could be mitigated by reducing air pollution emissions.