This paper studies the effect of air pollution on voting outcomes. We use data from 60 federal and state elections in Germany from 2000 to 2018 and exploit plausibly exogenous fluctuations in ambient air pollution within counties across election dates. Higher air pollution on election day shifts votes away from incumbent parties and towards opposition parties. An increase in the concentration of particulate matter (PM10) by 10 micrograms per cubic meter – around two within-county standard deviations – reduces the vote share of incumbent parties by two percentage points, which is equivalent to 4% of the mean vote share. We generalize these findings by documenting similar effects with data from a weekly opinion poll and a large-scale panel survey. We provide further evidence that emotions are a likely mechanism: the survey data show that poor air quality leads to greater anxiety and unhappiness, which may reduce the support for the political status quo. Overall, these results suggest that poor air quality affects decision-making in the population at-large, which has far-reaching knock-on effects on society.