The connection between six common air pollution particles and adult brain tumors: a meta-analysis of 26,217,930 individuals

Environmental air pollutants (black carbon (BC), nitrogen oxides (NO x ), particulate matter with diameter < 2.5 μm (PM 2.5 ), nitrogen dioxide (NO 2 ), particulate matter with diameter <10 μm (PM 10 ), and ozone (O 3 )) are one of the major menaces to mankind’s health globally. This analysis reviews the association between exposure to these air pollutants and the chance of developing brain tumors in adults (total brain tumors, malignant brain tumors, and benign brain tumors). Studies published by April 2022 were searched. Raw effect sizes were converted to standardized effect sizes per 10 μg/m 3 increase. Random effect models were applied to calculate combined effect size and 95% confidence intervals (CIs) were computed. A total of 8 articles were included for meta-analysis. The pooled effect size (ES) for per 10 μg/m 3 BC intake was 1.67 (95% CI: 1.25, 2.22), P = 0.449. For every 10 μg/m 3 rise in NO 2 concentration, ES was 1.03 (95% CI: 1.01, 1.05), P = 0.319. Meanwhile, there was a boundary association between NO x and adult brain tumors (ES and 95% CI: 1.01; 1.00, 1.01/10 μg/m 3 ; P = 0.716). While there was no conjunction between PM 2.5 , PM 10 , O 3 (PM 2.5 : ES and 95% CI: 1.04; 0.99, 1.08/10 μg/m 3 ; P = 0.834; PM 10 : ES and 95% CI: 1.01; 0.97, 1.04/10 μg/m 3 ; P = 0.627; O 3 : ES and 95% CI: 0.97; 0.94, 1.00/10 μg/m 3 ; P = 0.253). This research shows testimony of a significant link between air pollutants and brain tumors in adults, especially when exposed to BC, NO 2 , and NO x . This evidence emphasizes the importance of improving air quality as part of a comprehensive approach to prevent the occurrence and deterioration of brain tumors.