J. Jason West

An Estimate of the Global Burden of Anthropogenic Ozone and Fine Particulate Matter on Premature Human Mortality Using Atmospheric Modeling

Background Ground-level concentrations of ozone (O3) and fine particulate matter [≤ 2.5 μm in aerodynamic diameter (PM2.5)] have increased since preindustrial times in urban and rural regions and are associated with cardiovascular and respiratory mortality. Objectives We estimated the global burden of mortality due to O3 and PM2.5 from anthropogenic emissions using global atmospheric chemical transport model simulations of preindustrial and present-day (2000) concentrations to derive exposure estimates. Methods Attributable mortalities were estimated using health impact functions based on long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. Using simulated concentrations rather than previous methods based on measurements allows the inclusion of rural areas where measurements are often unavailable and avoids making assumptions for background air pollution. Results Anthropogenic O3 was associated with an estimated 0.7 ± 0.3 million respiratory mortalities (6.3 ± 3.0 million years of life lost) annually. Anthropogenic PM2.5 was associated with 3.5 ± 0.9 million cardiopulmonary and 220,000 ± 80,000 lung cancer mortalities (30 ± 7.6 million years of life lost) annually. Mortality estimates were reduced approximately 30% when we assumed low-concentration thresholds of 33.3 ppb for O3 and 5.8 μg/m3 for PM2.5. These estimates were sensitive to concentration thresholds and concentration–mortality relationships, often by > 50%. Conclusions Anthropogenic O3 and PM2.5 contribute substantially to global premature mortality. PM2.5 mortality estimates are about 50% higher than previous measurement-based estimates based on common assumptions, mainly because of methodologic differences. Specifically, we included rural populations, suggesting higher estimates; however, the coarse resolution of the global atmospheric model may underestimate urban PM2.5 exposures.

Global premature mortality due to anthropogenic outdoor air pollution and the contribution of past climate change

Increased concentrations of ozone and fine particulate matter (PM2.5) since preindustrial times reflect increased emissions, but also contributions of past climate change. Here we use modeled concentrations from an ensemble of chemistry?climate models to estimate the global burden of anthropogenic outdoor air pollution on present-day premature human mortality, and the component of that burden attributable to past climate change. Using simulated concentrations for 2000 and 1850 and concentration?response functions (CRFs), we estimate that, at present, 470?000 (95% confidence interval, 140?000 to 900?000) premature respiratory deaths are associated globally and annually with anthropogenic ozone, and 2.1 (1.3 to 3.0) million deaths with anthropogenic PM2.5-related cardiopulmonary diseases (93%) and lung cancer (7%). These estimates are smaller than ones from previous studies because we use modeled 1850 air pollution rather than a counterfactual low concentration, and because of different emissions. Uncertainty in CRFs contributes more to overall uncertainty than the spread of model results. Mortality attributed to the effects of past climate change on air quality is considerably smaller than the global burden: 1500 (?20?000 to 27?000) deaths yr?1 due to ozone and 2200 (?350?000 to 140?000) due to PM2.5. The small multi-model means are coincidental, as there are larger ranges of results for individual models, reflected in the large uncertainties, with some models suggesting that past climate change has reduced air pollution mortality.

Global Air Quality and Health Co-benefits of Mitigating Near-Term Climate Change through Methane and Black Carbon Emission Controls

Background: Tropospheric ozone and black carbon (BC), a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter; PM2.5), are associated with premature mortality and they disrupt global and regional climate. Objectives: We examined the air quality and health benefits of 14 specific emission control measures targeting BC and methane, an ozone precursor, that were selected because of their potential to reduce the rate of climate change over the next 20–40 years. Methods: We simulated the impacts of mitigation measures on outdoor concentrations of PM2.5 and ozone using two composition-climate models, and calculated associated changes in premature PM2.5- and ozone-related deaths using epidemiologically derived concentration–response functions. Results: We estimated that, for PM2.5 and ozone, respectively, fully implementing these measures could reduce global population-weighted average surface concentrations by 23–34% and 7–17% and avoid 0.6–4.4 and 0.04–0.52 million annual premature deaths globally in 2030. More than 80% of the health benefits are estimated to occur in Asia. We estimated that BC mitigation measures would achieve approximately 98% of the deaths that would be avoided if all BC and methane mitigation measures were implemented, due to reduced BC and associated reductions of nonmethane ozone precursor and organic carbon emissions as well as stronger mortality relationships for PM2.5 relative to ozone. Although subject to large uncertainty, these estimates and conclusions are not strongly dependent on assumptions for the concentration–response function. Conclusions: In addition to climate benefits, our findings indicate that the methane and BC emission control measures would have substantial co-benefits for air quality and public health worldwide, potentially reversing trends of increasing air pollution concentrations and mortality in Africa and South, West, and Central Asia. These projected benefits are independent of carbon dioxide mitigation measures. Benefits of BC measures are underestimated because we did not account for benefits from reduced indoor exposures and because outdoor exposure estimates were limited by model spatial resolution.

Marginal PM25: Nonlinear Aerosol Mass Response to Sulfate Reductions in the Eastern United States

Reductions in airborne sulfate concentration may cause inorganic fine particulate matter (PM25) to respond nonlinearly, as nitric acid gas may transfer to the aerosol phase. Where this occurs, reductions in sulfur dioxide (SO2) emissions will be much less effective than expected at reducing PM2.5. As a measure of the efficacy of reductions in sulfate concentration on PM , we define marginal PM2.5 as the local change in PM2.5 resulting from a small change in sulfate concentration. Using seasonal-average conditions and assuming thermodynamic equilibrium, we find that the conditions for PM2.5 to respond nonlinearly to sulfate reductions are common in the eastern United States in winter, occurring at half of the sites considered, and uncommon in summer, due primarily to the influence of temperature. Accounting for diurnal and intraseasonal variability, we find that seasonal-average conditions provide a reasonable indicator of the time-averaged PM2.5 response. These results indicate that reductions in sulfate concentration may be up to 50% less effective at reducing the annual-average PM2.5 than if the role of nitric acid is neglected. Further, large reductions in sulfate will also cause an increase in aerosol nitrate in many regions that are the most acidic.

What we breathe impacts our health: improving understanding of the link between air pollution and health

Air pollution contributes to the premature deaths of millions of people each year around the world, and air quality problems are growing in many developing nations. While past policy efforts have succeeded in reducing particulate matter and trace gases in North America and Europe, adverse health effects are found at even these lower levels of air pollution. Future policy actions will benefit from improved understanding of the interactions and health effects of different chemical species and source categories. Achieving this new understanding requires air pollution scientists and engineers to work increasingly closely with health scientists. In particular, research is needed to better understand the chemical and physical properties of complex air pollutant mixtures, and to use new observations provided by satellites, advanced in situ measurement techniques, and distributed micro monitoring networks, coupled with models, to better characterize air pollution exposure for epidemiological and toxicological research, and to better quantify the effects of specific source sectors and mitigation strategies.

The influence of ozone precursor emissions from four world regions on tropospheric composition and radiative climate forcing

0.4 2.6 to 1.9 1.3 Gg for NOx reductions, 0.1 1.2 to 0.9 0.8 Gg for NMVOC reductions, and 0.09 0.5 to 0.9 0.8 Gg for CO reductions, suggesting additional research is needed. The 100-year global warming potentials (GWP100) are calculated for the global CH4 reduction (20.9 3.7 without stratospheric O3 or water vapor, 24.2 4.2 including those components), and for the regional NOx, NMVOC, and CO reductions (18.7 25.9 to 1.9 8.7 for NOx, 4.8 1.7 to 8.3 1.9 for NMVOC, and 1.5 0.4 to 1.7 0.5 for CO). Variation in GWP100 for NOx, NMVOC, and CO suggests that regionally specific GWPs may be necessary and could support the inclusion

Burden of disease attributed to anthropogenic air pollution in the United Arab Emirates: estimates based on observed air quality data.

This study quantifies the national burden of disease attributed to particulate matter (PM) and ozone (O(3)) in ambient air in the United Arab Emirates (UAE), a rapidly growing nation in which economic development and climatic conditions pose important challenges for air quality management. Estimates of population exposure to these air pollutants are based on observed air quality data from fixed-site monitoring stations. We divide the UAE into small grid cells and use spatial-statistical methods to estimate the ambient pollutant concentrations in each cell based on the observed data. Premature deaths attributed to PM and O(3) are computed for each grid cell and then aggregated across grid cells and over a year to estimate the total number of excess deaths attributable to ambient air pollution. Our best estimate is that approximately 545 (95% CI: 132-1224) excess deaths in the UAE in the year 2007 are attributable to PM in ambient air. These excess deaths represent approximately 7% (95% CI: 2-17%) of the total deaths that year. We attribute approximately 62 premature deaths (95% CI: 17-127) to ground-level O(3) for the year 2007. Uncertainty in the natural background level of PM, due to the frequent dust storms occurring in the region, has significant impacts on the attributed mortality estimates. Despite the uncertainties associated with the integrated assessment framework, we conclude that anthropogenic ambient air pollution, in particular PM, causes a considerable public health impact in the UAE in terms of premature deaths. We discuss important uncertainties and scientific hypotheses to be investigated in future work that might help reduce the uncertainties in the burden of disease estimates.

Storms, Investor Decisions, and the Economic Impacts of Sea Level Rise

Past research on the economic impacts of aclimate-induced sea level rise has been based on thegradual erosion of the shoreline, and humanadaptation. Erosion which is accelerated by sea levelrise may also increase the vulnerability to stormdamage by decreasing the distance between the shoreand structures, and by eroding protective coastalfeatures (dunes). We present methods of assessingthis storm damage in coastal regions where structuralprotection is not pursued. Starting from the boundingcases of no foresight and perfectforesight of Yohe et al. (1996), we use adisaggregated analysis which models the random natureof storms, and models market valuation and privateinvestor decisions dynamically. Using data from theNational Flood Insurance Program and a hypotheticalcommunity, we estimate that although the total stormdamage can be large, the increase in storm damageattributable to sea level rise is small (<5% oftotal sea level rise damages). These damages,however, could become more significant under otherreasonable assumptions or where dune erosion increasesstorm damage.

The Impact of Individual Anthropogenic Emissions Sectors on the Global Burden of Human Mortality due to Ambient Air Pollution.

Background: Exposure to ozone and fine particulate matter (PM2.5) can cause adverse health effects, including premature mortality due to cardiopulmonary diseases and lung cancer. Recent studies quantify global air pollution mortality but not the contribution of different emissions sectors, or they focus on a specific sector. Objectives: We estimated the global mortality burden of anthropogenic ozone and PM2.5, and the impact of five emissions sectors, using a global chemical transport model at a finer horizontal resolution (0.67° × 0.5°) than previous studies. Methods: We performed simulations for 2005 using the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4), zeroing out all anthropogenic emissions and emissions from specific sectors (All Transportation, Land Transportation, Energy, Industry, and Residential and Commercial). We estimated premature mortality using a log-linear concentration–response function for ozone and an integrated exposure–response model for PM2.5. Results: We estimated 2.23 (95% CI: 1.04, 3.33) million deaths/year related to anthropogenic PM2.5, with the highest mortality in East Asia (48%). The Residential and Commercial sector had the greatest impact globally—675 (95% CI: 428, 899) thousand deaths/year—and in most regions. Land Transportation dominated in North America (32% of total anthropogenic PM2.5 mortality), and it had nearly the same impact (24%) as Residential and Commercial (27%) in Europe. Anthropogenic ozone was associated with 493 (95% CI: 122, 989) thousand deaths/year, with the Land Transportation sector having the greatest impact globally (16%). Conclusions: The contributions of emissions sectors to ambient air pollution–related mortality differ among regions, suggesting region-specific air pollution control strategies. Global sector-specific actions targeting Land Transportation (ozone) and Residential and Commercial (PM2.5) sectors would particularly benefit human health. Citation: Silva RA, Adelman Z, Fry MM, West JJ. 2016. The impact of individual anthropogenic emissions sectors on the global burden of human mortality due to ambient air pollution. Environ Health Perspect 124:1776–1784; http://dx.doi.org/10.1289/EHP177

Co-benefits of Global Greenhouse Gas Mitigation for Future Air Quality and Human Health.

Actions to reduce greenhouse gas (GHG) emissions often reduce co-emitted air pollutants, bringing co-benefits for air quality and human health. Past studies1–6 typically evaluated near-term and local co-benefits, neglecting the long-range transport of air pollutants7–9, long-term demographic changes, and the influence of climate change on air quality10–12. Here we simulate the co-benefits of global GHG reductions on air quality and human health using a global atmospheric model and consistent future scenarios, via two mechanisms: a) reducing co-emitted air pollutants, and b) slowing climate change and its effect on air quality. We use new relationships between chronic mortality and exposure to fine particulate matter13 and ozone14, global modeling methods15, and new future scenarios16. Relative to a reference scenario, global GHG mitigation avoids 0.5±0.2, 1.3±0.5, and 2.2±0.8 million premature deaths in 2030, 2050, and 2100. Global average marginal co-benefits of avoided mortality are