Air Pollution and Precursor Emissions

Air pollution can have serious short-term and long-term health effects. Recent research suggests that climate change is likely to have an impact on pollution levels and therefore a corresponding effect on human health. Tagaris et al. (2010) studied the relative contribution of particulate matter (PM2.5) and ozone (O3) precursor emissions to air pollution-related premature mortality, and estimated the sensitivities of premature mortality to emissions. Additionally the paper provides an estimate for the emissions reductions needed to offset mortalities related to PM2.5 and O3. The authors found that states with significant premature mortality increases due to PM2.5 will benefit in the future from reductions of SO2, anthropogenic NOx, and NH3. States with significant premature mortality increases due to O3 will benefit most from NOx emission reductions.  Therefore the authors determined that PM2.5 and O3 induced premature mortality modulated by climate change could be offset in most states by reducing just one precursor emission class. Carolyn Campbell
Tagaris, E., Liao, K., DeLucia, A.J., Deck, L., Amar, P., Russel, A.G., 2010. Sensitivity of air pollution-induced premature mortality to precursor emissions under the influence of climate change. International Journal of Environmental Research and Public Health 7, 2222–2237.

The United States has the third highest level worldwide of premature death from outdoor air pollution after, China and India. Ozone (O3) and particulate matter (PM2.5) have particularly negative effects on human health. Exposure to O3 decreases lung function, increases airway reactivity, causes lung inflammation, and decreases exercise capacity. PM2.5 exposure causes increased rates of respiratory symptoms and illness, decreased lung function, increased asthma exacerbation, impaired cardiovascular responses, and altered blood coagulation. Climate change is expected to have an impact on O3 and PM2.5 concentrations with higher temperatures and more frequent stagnation events that will lead to increased ground-level O3 concentrations, while changes in precipitation will affect concentrations of PM2.5.
In order to study the relationship of O3 and PM2.5 precursor emission in premature mortality change, results from the Goddard Institute for Space Studies Global Climate Model and components of the Models-3 atmospheric modeling system were used to simulate how climate and emissions changes affect air quality. The USEPA’s BENMAP was then used to translate air quality changes into health impacts. To estimate the relative contribution of PM2.5 and O3 precursor emissions in premature mortality changes in each U.S. state the authors used EX(Y) = (∆MX/∆CX)SX(Y) where EX(Y) is the mortality change induced by changes in pollutant X concentration due to a 1% reduction in precursor Y emissions over the domain, ∆CX is the pollutant X concentration change due to climate change, ∆MX is the premature mortality change induced by ∆CX, SX(Y) is the sensitivity of pollutant X to precursor emissions, X is PM2.5 or O3 concentrations, and Y is SO2, NOx, NH3, or VOC emissions. Linear responses of pollutant concentrations to precursor emissions were used to estimate the reduction needed in precursor emissions to offset air-pollution induced mortality due to climate change.
States with high emissions rates and premature mortality increases due to PM2.5 concentrations modulated by climate change were found to benefit most from emissions reductions of SO2, anthropogenic NOx, or NH3. States with premature mortality increases due to O3 concentrations modulated by climate change were found to derive the most benefit from anthropogenic NOx emissions reductions. Additionally, combining reductions of more than one precursor emission class was found to have a synergistic result. 

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