The Association Between Air Pollution Exposure and White Blood Cell Counts: A Nationwide Cross-Sectional Survey in South Korea.

The effect of air pollution, a major global health issue, on the immune system, particularly on white blood cell (WBC) counts, remains underexplored. This study utilized data from 54,756 participants in the Korean National Health and Nutrition Examination Survey to investigate the effects of short- (day of examination and 7-day averages), mid- (30- and 90-day averages), and long-term (one-, three-, and five-year averages) air pollutant exposure on WBC counts. We assessed exposure to particulate matter (PM, PM), sulfur dioxide (SO), nitrogen dioxide (NO), ozone (O), and carbon monoxide (CO). Linear regression with log-transformed WBC counts, adjusted for confounders, showed that PM was positively associated with long-term exposure, PM was negatively associated with short- and mid-term exposures, SO was consistently negatively associated with short- and mid-term exposures, NO and CO were positive across most periods, and O was negatively associated with short- and mid-term exposures. Logistic regression analysis confirmed these findings, showing that short- and mid-term exposure to PM, PM, and SO was negatively associated with the risk of belonging to the high-WBC group, while long-term exposure to PM, PM, NO, and CO showed positive associations with risk. Our findings highlight the time- and pollutant-specific associations between air pollution exposure and WBC counts, underscoring air pollution's potential impact on systemic inflammation.