Is there a link between air pollution and impaired memory? Evidence on 34,000 English citizens

Summary

It is known that people feel less happy in areas with higher levels of nitrogen dioxide NO2 (MacKerron and Mourato, 2009). What else might air pollution do to human wellbeing? This paper uses data on a standardized word-recall test that was done in the year 2011 by 34,000 randomly sampled English citizens across 318 geographical areas. We find that human memory is worse in areas where NO2 and PM10 levels are greater. The paper provides both (i) OLS results and (ii) instrumental-variable estimates that exploit the direction of the prevailing westerly wind and levels of population density. Although caution is always advisable on causal interpretation, these results are concerning and are consistent with laboratory studies of rats and other non-human animals. Our estimates suggest that the difference in memory quality between England’s cleanest and most-polluted areas is equivalent to the loss of memory from 10 extra years of ageing.