We study the effect of air pollution on the daily productivity of workers in a Chinese call center. Our results suggest that air pollution reduces the workers’ call volume each day. In addition, we study a randomized-controlled trial at the call center, in which workers who volunteered for the trial were randomly assigned to either work from home or at the office. We find suggestive evidence that the workers who volunteered for the experiment were more sensitive to pollution than other workers. For employees who did work from home, we observe a much smaller effect of pollution on productivity when they are at home. The results suggest that workplace policies that allow workers to sort into employment locations is one potential approach for mitigating the negative effects from poor air quality.