Pollution and learning: Causal evidence from Obama’s Iran sanctions

We provide evidence of a substantial impact of pollution in the vicinity of a school on student learning using standardized test results from the universe of Tehran junior schools. Causal identification exploits that the 2010 US sanctions prevented the sale of refined petroleum products to Iran which differentially impacted air quality at schools in the city, depending on the location of each with respect to the road network. Relative performance dropped at more road-exposed (variously-measured) schools. Roads upwind appear to have four times the impact compared to those downwind, aligning with the prevailing wind direction which blows 80% of the time from the west, a finding that also provides compelling evidence against alternative interpretations.