The adverse health impacts of air pollution have been subject of much research and provide the usual rationale for policy interventions in this area. It is only recently being recognized that polluted air might also imply direct economic costs by reducing labor productivity. Recent studies show that that short-term exposure to ozone (O3) and particulate matter (PM2.5) significantly reduces the daily productivity of unskilled workers engaged in physical work (fruit picking and packing). However, most work - and in particular most high value work - in a modern economy is based on mental-dexterity, often with little or no physical dimension (e.g. lawyers, administrators, teachers, financiers, computer programmers). Thus, there is a strong interest in studying the impact of pollution on cognitive performances. We take advantage of the design of the US HRS survey (respondents are reinterviewed every two years) to study this relationship. We find that exposure to PM2.5at the WHO recommended maximum daily pollution level of 25μg/m3reduces performances by 2.5%, that this effect is approximately linear above 15μg/m3, and robust to a variety of specifications.