Professor Fowlie notes in her recent EI blog "When policymakers set air pollution standards, they’re typically more focused on first-order health impacts versus impacts on job performance. Unlike data on umpire calls, however, data on individuals’ health outcomes and medical history are private. The most rigorous research on health impacts uses confidential data to isolate the effects of air pollution on health. Indirectly, we have these health-based studies to thank for past, policy-induced improvements in U.S. air quality."