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

This meta-analysis aimed to explore the association between short-term exposure to air pollution and schizophrenia (SCZ)¹1SCZ: schizophrenia., and investigate the susceptible population and the lag characteristics of different pollutants. 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 (PM₂.₅)²2PM₂.₅: particle with aerodynamic diameter ≤2.5 μm., 2.5 μm < diameter < 10 μm (PMC)³3PMC: particle with 2.5 μm < diameter <10 μm., ≤10μm (PM₁₀)⁴4PM₁₀: particle with aerodynamic diameter ≤10 μm.) and gaseous pollutants (nitrogen dioxide (NO₂)⁵5NO₂: nitrogen dioxide., sulfur dioxide (SO₂)⁶6SO₂: sulfur dioxide., carbon monoxide (CO)⁷7CO: carbon monoxide.) with SCZ. Relative risk (RR)⁸8RR: relative risk. 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. 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 PM₂.₅ (RR: 1.0050, 95 % confidence interval (CI)⁹9CI: confidence interval.: 1.0017, 1.0083), PMC (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 PM₂.₅ and PM₁₀. Gaseous pollutants presented the immediate risk, and particulates showed the delayed risk. The present meta-analysis suggests that short-term exposure to PM₂.₅, PMC, PM₁₀, SO₂, and NO₂ exposure may be associated with an elevated risk of SCZ.