Could air pollution be a source of stress, anxiety or even depression? This is a question researchers around the world are trying to answer.
In April, a study published by the European Society of Cardiology reported an increased risk of episodes of stress and depression in those most exposed, which, by extension, could increase the risk of death from cardiovascular disease.
Now, new findings from researchers at Bristol University in the UK bring further cause for concern. This research suggests that a baby’s exposure to air pollution while in the womb is associated with the development of certain mental health issues in adolescence.
“Our 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,” study lead author Dr Joanne Newbury observed.
The aim of this research was to assess the long-term impact of exposure to noise and air pollution during three key periods – pregnancy, infancy and adolescence – on three mental health disorders (psychotic experiences, depression and anxiety).
The scientists analysed data from 9,065 participants in the Avon Longitudinal Study of Parents and Children, a study that included over 14,000 pregnant women in the early 1990s.
They found that, while exposure to noise pollution during childhood and adolescence was linked to anxiety symptoms, exposure to air pollution was associated with an increased risk of psychotic experiences and depression.
Published in the journal Jama Network Open, the research reports that each 0.72 microgramme-per-cubic-metre (µg/m3) increase in fine particles during pregnancy and childhood was linked to an 11% and 9% increase in the risk of psychotic experiences in adolescence and early adulthood, respectively.
The researchers also report an increased risk of depression (+10%) for this level of exposure during pregnancy.
While this is an observational study, it is important to note that all these associations were still significant after controlling for other risk factors, including family psychiatric history.
“Childhood, adolescence, and early adulthood are critical periods for the development of psychiatric disorders: worldwide, nearly two-thirds of those affected become unwell by age 25,” Newbury noted.
“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.”
She concluded: “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.”
According to the World Health Organization (WHO), in 2019, almost all the world’s population (99%) was living in places where air pollution guideline levels were not met.
Meanwhile, the latest report from Swiss company IQAir revealed that Bangladesh, Pakistan, India, Tajikistan and Burkina Faso were the five most polluted countries in 2023, with annual exposure to fine particles up to 15 times higher than the annual WHO recommendation of 5 µg/m3 or less.