Air pollution tied to ED visits for mental health problems

Higher ambient levels of ozone (O₃) or fine particles (PM_2.5) seem to aggravate the risk of mental health problems, a recent study has found. Underlying biological mechanisms remain poorly understood.

Data for the analysis were drawn from the US Environmental Protection Agency and from the California Office of Statewide Health Planning and Development. Mental health outcomes assessed included psychosis, neurosis, substance use, depression, schizophrenia, self-harm/suicide, and mood/affective disorders, among others.

Over the observation period, a total of 1,997,992 mental health-related emergency department (ED) visits were recorded, most of which were due to homicides or injuries purposely inflicted by other persons. More than 100,000 cases each for depression and bipolar-related concerns were logged, and nearly 200,000 visits for self-harm/suicide were reported.

Each 10-ppb increase in the 7-day average level of O₃ correlated with a 1.52-percent (95 percent confidence interval [CI], 0.69–2.36) increase in the likelihood of ED visits for mood and affective disorders. In particular, risks for bipolar (2.83 percent, 95 percent CI, 1.53–4.07) and depression (1.86 percent, 95 percent CI, 0.62–3.15) were heightened.

Seven-day ozone was likewise associated with greater self-harm/suicide ED visits, while 30-day averages were linked to homicide/inflicted injury and neurotic disorder visits.

Similarly, each 10-µg/m³ increase in short-term PM_2.5 exposure correlated with all mental health-related ED visits, particularly for neurotic disorders and inflicted injuries.

“While the research literature is increasing, there still exists a knowledge gap on how air pollution affects mental health among subgroups,” the researchers said. “Future epidemiological studies should continue examining the effects of pollutant exposure by gender, age, and race/ethnicity.”

“Our study’s findings also support the need to better understand the biological mechanisms between exposure to air pollution and mental health outcomes,” they added.