How environmental risks affect mental health: evidence for air pollution, chemicals and noise

Background

The evidence for many physical health effects due to air pollution (AP), chemicals and transportation noise is robust. However, especially their effects on mental health remain less well characterized.

Methods

We conducted an umbrella+ review, synthesizing evidence from reviews, meta-analyses and original studies published from 2015 to 2025 on associations between the three environmental determinants and mental health in the general population.

Results

Overall, the review yielded 168 studies included in the analyses (AP: n = 93; Chemicals: n = 49; Noise: n = 26). For AP an association between long-term ambient particulate matter pollution and NO2 with depression was consistently reported. Short-term exposure to these air pollutants was associated with worsening of depressive symptoms and exacerbation of schizophrenia. Comparable links to depressive symptoms were observed for SO₂ and CO. In terms of chemicals second hand smoke exposure during pregnancy was associated with maternal postnatal depression, whereas lead exposure in the same period was linked to schizophrenia in the offspring later in life. Long-term, non-occupational pesticide exposure was also associated with depressive symptoms. For noise, depression was linked to exposure to road traffic and aircraft noise in adults. For children, road traffic noise was linked to outcomes such as behavioural problems. No coherent association of mental health outcomes due to railway noise was identified.

Discussion

Despite the generally availability of studies indicating associations between the three determinants and mental health the levels of evidence remain moderate. Especially in more urban locations where these exposures co-occur, their combined effects need to be disentangled before causal relationships can be established. Our results confirm the need for more longitudinal research to establish causal effects. Moreover, variability in exposure assessment methods limits comparability across studies.

Key messages

• Air pollution, chemicals, and transportation noise are consistently linked to depression and other mental health outcomes, but evidence levels remain moderate.

• Co-occurring environmental exposures and inconsistent methods hinder causal conclusions, highlighting the need for longitudinal research.