Using large-scale high-granularity data from a food delivery platform and granular pollution and weather information, we study how PM2.5 fluctuations affect riders' absenteeism, productivity, and accidents. Exploiting exogenous pollution variation from inverse boundary layer height, we find that higher pollution increases absenteeism for all workers and raises delivery times and accident rates only among (e-)bike riders, who must exert physical effort while working. Affected workers compensate productivity losses by working longer hours. Monetary incentives mitigate the effects on absenteeism but do not offset the decline in productivity and appear to exacerbate accident risk.