Short-term exposure to air pollution is an emerging but neglected risk factor for schizophrenia: A systematic review and meta-analysis

Abstract

Objective: This meta-analysis aimed to explore the association between short-term exposure to air pollution and schizophrenia (SCZ)¹, and investigate the susceptible population and the lag characteristics of different pollutants.

Methods: A systematic review and meta-analysis was conducted by searching PubMed, Cochrane, Web of Sciences, and CNKI for relevant literature published up to 28 Feb 2022. Meta-analysis was performed separately to investigate the association of ambient particulates (diameter ≤ 2.5 μm (PM_2.5)², 2.5 μm < diameter < 10 μm (PM_C)³, ≤10μm (PM₁₀)⁴) and gaseous pollutants (nitrogen dioxide (NO₂)⁵, sulfur dioxide (SO₂)⁶, carbon monoxide (CO)⁷) with SCZ. Relative risk (RR)⁸ per 10 μg/m³ increase in air pollutants concentration was used as the effect estimate. Subgroup analyses were conducted by age, gender, country, median pollutant concentration, and median temperature.

Results: We identified 17 articles mainly conducted in Asia, of which 13 were included in the meta-analysis. Increased risk of SCZ was associated with short-term exposure to PM_2.5 (RR: 1.0050, 95 % confidence interval (CI)⁹: 1.0017, 1.0083), PM_C (1.0117, 1.0023, 1.0211), PM₁₀ (1.0047, 1.0025, 1.0070), NO₂ (1.0275, 1.0132, 1.0420), and SO₂ (1.0288, 1.0146, 1.0432) exposure. Subgroup analyses showed that females may be more susceptible to SO₂ and NO₂, and the young seem to be more sensitive to PM_2.5 and PM₁₀. Gaseous pollutants presented the immediate risk, and particulates showed the delayed risk.

Conclusions: The present meta-analysis suggests that short-term exposure to PM_2.5, PM_C, PM₁₀, SO₂, and NO₂ exposure may be associated with an elevated risk of SCZ.

Keywords: Gaseous pollutants; Particulates; Schizophrenia.