Out of over 14,000 infants born between 1991 and 1993 in Southwest England, mental health data was available for over 9,000, including measurements of psychotic experiences, depression, and anxiety at ages 13, 18, and 24. Air pollution, measured as fine particulate matter with a diameter smaller than 2.5 μm (PM2.5) as well as nitrogen dioxide (NO2), were estimated using geocodes from age 0-12 and predicted by the Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) model. Exposure to noise pollution was also calculated, primarily from exposure to road traffic noise.
The data indicated that early PM2.5 exposure was associated with more psychotic experiences later in life, as well as more depression (exposure during pregnancy only), while higher noise pollution was linked to greater anxiety. A number of potential mechanisms are discussed, including air pollution-induced epigenetic changes, as well as increases in premature birth and restricted fetal growth. The effect of very small increases in PM2.5 during pregnancy on the risk of depression during pregnancy was substantially higher than previously reported for adult particulate matter exposure, suggesting that pregnancy is a particularly sensitive period for exposure to air pollution.