Impacts of global, regional, and sectoral black carbon emission reductions on surface air quality and human mortality
1US Environmental Protection Agency, 109 TW Alexander Dr., Research Triangle Park, NC 27711, USA
2Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
3Inst. for the Environment, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Abstract. As a component of fine particulate matter (PM2.5), black carbon (BC) is associated with premature human mortality. BC also affects climate by absorbing solar radiation and reducing planetary albedo. Several studies have examined the climate impacts of BC emissions, but the associated health impacts have been studied less extensively. Here, we examine the surface PM2.5 and premature mortality impacts of halving anthropogenic BC emissions globally, from eight world regions, and from three major economic sectors. We use a global chemical transport model, MOZART-4, to simulate PM2.5 concentrations and a health impact function to calculate premature cardiopulmonary and lung cancer deaths. We estimate that halving global anthropogenic BC emissions reduces outdoor population-weighted average PM2.5 by 542 ng m−3 (1.8%) and avoids 157 000 (95% confidence interval, 120 000–194 000) annual premature deaths globally, with the vast majority occurring within the source region. While most of these avoided deaths can be achieved by halving East Asian emissions (54%), followed by South Asian emissions (31%), South Asian emissions have 50% greater mortality impacts per unit BC emitted than East Asian emissions. Globally, the contribution of residential, industrial, and transportation BC emissions to PM2.5-related mortality is 1.3, 1.2, and 0.6 times each sector's contribution to anthropogenic BC emissions, owing to the degree of co-location with population. Impacts of residential BC emissions are underestimated since indoor PM2.5 exposure is excluded. We estimate ~8 times more avoided deaths when BC and organic carbon (OC) emissions are halved together, suggesting that these results greatly underestimate the full air pollution-related mortality benefits of BC mitigation strategies which generally decrease both BC and OC. Confidence in our results would be strengthened by reducing uncertainties in emissions, model parameterization of aerosol processes, grid resolution, and PM2.5 concentration-mortality relationships globally.