Air Pollution and Cognition in Children: Evidence from National Tests in Denmark

with Christina M. Andersen, Timo Hener, Marianne Simonsen, Lars Skipper, Jørgen Brandt, Jesper H. Christensen, Lise M. Frohn, and Camilla Geels

This paper studies the effects of daily variation in outdoor air pollution on student test scores. We utilize Danish register data of the full population of elementary and lower secondary school students, who take mandatory national tests in math and reading. We match the home address of students to a 1x1 km grid of air pollution to obtain test date and lifetime pollution measures. We find that an increase in fine particles (PM2.5), corresponding to the change from a very clean to an average polluted day, reduces student performance in math by 1.8% and in reading by 0.9% of a standard deviation. The impacts are largest in the upper part of the test score distribution in math, suggesting that higher mental processes are most susceptible to air pollution. We do not find evidence of heterogeneity by previous health conditions, socio- economics status, or life-time pollution exposure, despite using abundant amounts of register data information.