Relying on a quasi-natural experiment instituted by air quality regulations during the 2008 Beijing Olympic Games, we examine the effect of air pollution on auditors’ behaviours. We find that a 1-percent increase in the air pollution index increases the percentage of work hours necessary for an auditor to audit a firm by 4 percent. This effect is more pronounced when the leader of an audit team is more entrenched, is older, or male. Further analysis reveals that audit quality and audit fees are not affected by air pollution. We conclude that air pollution reduces auditors’ work efficiency.