Long-Term Exposure to Air Pollution Associates the Risk of Benign Brain Tumor: A Nationwide, Population-Based, Cohort Study in Taiwan.

Air pollutants as risk factors for benign brain tumor (BBT) remain unclear. Therefore, we conducted a nationwide retrospective cohort study by integrating the patients' clinical data and daily air quality data to assess the environmental risk factors of BBT in Taiwan.Daily air quality data were categorized into quartiles (Q1 to Q4). The adjusted hazard ratio (aHR) was evaluated by comparing the BBT incidence rate of the subjects in Q2-Q4 with that of the subjects in Q1 (the lowest concentration of air pollutants). A total of 161,213 subjects were enrolled in the study. Among the air pollutants tested, the aHR of BBT was significantly higher in the subjects who were exposed to the highest level (Q4) of CO (aHR 1.37, 95% CI 1.08-1.74), NO 2 (aHR 1.40, 95% CI 1.09-1.78), and PM 2.5 (aHR 1.30, 95% CI 1.02-1.65) than that in the subjects who were exposed to the lowest level (Q1). No significant risk association of BBT with SO 2 and PM 10 exposure was observed. The results revealed that long-term exposure to air pollutants, particularly CO, NO 2 , and PM 2.5 , is associated with the risk of BBT.