Blackmores Institute

“Particulate air pollution’s physical effects are well known, but associations between particulate matter (PM) exposure and mental illness have not been yet established. However, there is an increasing interest in emerging evidence supporting a possible etiological link.
 
 “We undertook a systematic review and meta-analysis and found associations between long-term (&gt; 6 months) PM &lt;2.5µm in aerodynamic diameter exposure and depression – the pooled odds ration was 1.102 per µg/m3 PM2.5 increase (95% CI: 1.023, 1.189; I2 = 0.00%). Indicating that higher PM2.5 exposure is associated with higher odds of depression,” the authors reported.
 
 The analysis also found a statistically significant positive association between PM2.5 exposure and anxiety symptoms, with one study finding a strong link between PM2.5 exposure and moderate-to-severe anxiety symptoms.
 
 In addition, researchers found a possible association between short-term PM10 exposure and suicide risk.
 
 “The effect sizes observed in the studies of associations between long-term PM2.5 exposure and depression and anxiety identified by our review are similar in magnitude to those observed for some physical health consequences of chronic air pollution exposure. For example, a 10 µg/m3 increase in long-term average PM2.5 exposure appears to be associated with an approximately 10 percent increase in all-cause mortality.” 
 
 “If global mean population-weighted PM2.5 exposure (43.9 µg/m3) were reduced to a population-weighted mean PM2.5 exposure of 25.0 µg/m3 (the current EU-recommended limit), depression risk could be reduced by up to 15.2% (95% CI:3.85,25.9%),” the authors said.
 
 While acknowledging that physical comorbidities may both confound and/or mediate the associations found in the review, the authors also pointed to good evidence from human and animal studies that may explain how PM exposure affect mental health outcomes. Potential biological mechanisms include: PM exposure induces oxidative and nitrosative stress, along with systemic and neuro-inflammation as well as being directly neurotoxic and associated with structural brain changes. It has also been found to affect stress hormone production. 
 
 “In view of the potentially significant mental health risks that may be posed by PM exposure, particularly over the longer term, further high-quality studies are warranted to more fully investigate the exposure–response relationships and mechanisms involved,” the authors stated.
 
 “Our findings support the hypothesis of an association between long-term PM2.5 exposure and depression, as well as supporting hypotheses of possible associations between long-term PM2.5 exposure and anxiety, and between short-term PM10 exposure and suicide.”
 
 “The possibility of causal associations between air pollution and adverse mental health outcomes raises equity concerns given that deprivation is known to adversely affect mental health, whereas poorer areas often have more polluted air. There are, nevertheless, valuable opportunities to reduce the burden of both mental and physical ill health and health inequalities simultaneously through well designed policies to improve air quality, such as by promoting active travel and urban green spaces, which also have psychological benefits,” the authors concluded.Source:
 Environ Health Perspect. 2019 Dec;127(12):126002. doi: <a href="https://doi.org/10.1289/EHP4595 ">10.1289/EHP4595</a>

Air pollution may be damaging more than our lungs with findings of a systematic review supporting the hypothesis that there is an association between long-term exposure to air pollution and depression.

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