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. The 2010 US sanctions prevented the sale of refined petroleum products to Iran. Causal identification exploits that the impact of sanctions on air quality in the vicinity of schools in the city varied according to the proximity of each school to roads. Relative academic 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.