The impact of weather changes on air quality and health in the United States in 1994-2012

Abstract

Air quality is heavily influenced by weather conditions. In this study, we assessed the impact of longterm weather changes on air quality and health in the US during 1994-2012.Wequantified past weather-related increases, or 'weather penalty', in ozone (O3) and fine particulate matter (PM2.5), and thereafter estimated the associated excess deaths. Using statistical regression methods, we derived the weather penalty as the additional increases in air pollution relative to trends assuming constant weather conditions (i.e., weather-adjusted trends). During our study period, temperature increased and wind speed decreased in most US regions. Nationally, weather-related 8 h maxO3 increases were 0.18 ppb per year (95% CI: 0.06, 0.31) in the warm season (May-October) and 0.07 ppb per year (95% CI: 0.02, 0.13) in the cold season (November-April). The weather penalties onO3 were relatively larger thanPM2.5 weather penalties, which were 0.056 μgm-3 per year (95% CI: 0.016, 0.096) in warm months and 0.027 μgm-3 per year (95% CI: 0.010, 0.043) in cold months. Weather penalties onO3 andPM2.5 were associated with 290 (95% CI: 80, 510) and 770 (95% CI: 190, 1350) excess annual deaths, respectively. Over a 19-year period, this amounts to 20 300 excess deaths (5600 fromO3, 14 700 fromPM2.5) attributable to the weather penalty on air quality.