Assessing the National Public Health Burden Associated with Exposure to Ambient Black Carbon in the United States

Background : Black carbon (BC) is a significant component of fine particulate matter (PM2.5) air pollution, which has been linked to a series of adverse health effects, in particular premature mortality. Recent scientific research indicates that BC also plays an important role in climate change. Therefore, controlling black carbon emissions provides a great opportunity for a double dividend.

Aims : This study quantifies the national burden of mortality attributable to long-term exposure to ambient BC among adults in the United States (US).

Methods : We use GEOS-Chem, a global 3-D model of atmospheric composition to estimate the 2010 annual average BC levels at a 12-km grid resolution across the continental US. Using PM2.5 mortality risk coefficient drawn from the American Cancer Society cohort study, the numbers of deaths due to BC exposure were estimated for each 12-km grid, and then aggregated to the county, state and national level. States and counties were ranked by both total number of deaths and percentage of deaths attributable to BC. Given recent evidence that BC particles may pose a greater risk on human heath than other components of PM2.5, we also conducted sensitivity analysis using BC-specific risk coefficients drawn from recent literature.

Results : We estimated approximately 14,000 deaths to result from the 2010 BC levels. The total number of BC-related deaths was the greatest in the State of California, and the percentage of BC-related deaths was the greatest in the State of New Jersey. Sensitivity analysis indicates that the total BC-related mortality could be up to ten times larger than the above estimate.

Conclusion : Our findings indicate that controlling BC emissions would have substantial co-benefits for public health in the US.