Will Climate Warming Enhance Air Pollution?

This study of 50 eastern US cities predicts an increase in summertime ozone levels by 2050 relative to 1990 leading to a significant rise in the daily total mortality rate within the metropolitan areas studied. Using a climate/air quality modeling system to project changes in future ground-level ozone in 50 eastern U.S. cities the study isolated the response of near-surface ozone concentrations to climate change, while assuming constant anthropogenic emissions. Hourly ambient ozone concentration levels from the summers of 1993-1997 were compared to those projected for 2053-2057 summers based on the IPCC A2 scenario. The study also looked at changes in "exceedance days" relative to current regulatory standards. The model projected daily average maximum ozone level increases of 4.8 and 4.4 ppb (1- and 8-h maximum) between 1990 and 2050, with the largest increases expected for cities already experiencing elevated ozone levels. The number of exceedance days increased for both the 1- and 8h studies, by an average of 0.6 and 5.5 days respectively, while the Air Quality Index (AQI) scale showed a 10% increase in the number of days with "adverse health effects" and an 8% increase in days with 'unhealthy conditions'. Based on concentration/response functions, the simulated changes in ground-level ozone concentrations correspond to an approximate increase of 0.11% to 0.27% in daily total mortality.

Source: Bell, M., Goldberg, R., Hogrefe, C., et al., 2007. Climate change, ambient ozone, and health in 50 US cities. Climatic Change 82: 61-76.