Air pollution during pregnancy: impact on mental health

A team from  the University of Bristol have examined the effect of prenatal exposure to air pollution on the impact to the mental health of the children as they grow.

The Bristol team examined the association between air and noise pollution exposure in pregnancy, childhood, and adolescence with psychotic experiences, depression, and anxiety in children from ages 13 to 24 years.

They used data from over 9,000 women who were recruited to a birth cohort study between 1991 and 1992 and for whom mental health records existed. The lives of these women and their children has been monitored ever since.

The study focussed on mental health reports at the ages of 13, 18 and 24 years, mapping these against outdoor air and noise pollution in Bristol at the time.

The researchers found that relatively small increases in PM2.5 levels during pregnancy, and subsequently during childhood, were associated with an increased risk of psychotic experiences as well as depression. Higher noise pollution exposure in childhood and adolescence increased the risk of suffering anxiety. 

Every 0.72 μg/m³ increase in PM2.5 during pregnancy was associated with an 11% increased chance of psychotic experiences, the same increases during childhood increased those chances by 9%.

Similarly, every 0.72 μg/m³ increase in PM2.5 during pregnancy was associated with a 10% increase in the likelihood of depression.

Dr Joanne Newbury, Sir Henry Wellcome Postdoctoral Research Fellow in the University’s Bristol Medical School: Population Health Sciences (PHS) and the study’s lead author, said: ‘Childhood, adolescence, and early adulthood are critical periods for the development of psychiatric disorders: worldwide, nearly two-thirds of those affected become unwell by the age of 25. Our findings add to a growing body of evidence – from different populations, locations, and using different study designs – suggesting a detrimental impact of air pollution (and potentially noise pollution) on mental health.

‘This is a major concern, because air pollution is now such a common exposure, and rates of mental health problems are increasing globally. Given that pollution is also a preventable exposure, interventions to reduce exposure, such as low emissions zones, could potentially improve mental health. Targeted interventions for vulnerable groups including pregnant women and children could also provide an opportunity for more rapid reductions in exposure.

‘It is important to emphasise that these findings, by themselves, do not prove a causal association. However, other recent studies have shown that low emissions zones appear to have a positive impact on mental health.’

The full research can be read here.