Abstract
Background: The effect of air pollution, a major global health issue, on the immune system, particularly on white blood cell (WBC) counts, remains underexplored. Methods: 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(10), PM(2.5)), sulfur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)), and carbon monoxide (CO). Results: Linear regression with log-transformed WBC counts, adjusted for confounders, showed that PM(10) was positively associated with long-term exposure, PM(2.5) was negatively associated with short- and mid-term exposures, SO(2) was consistently negatively associated with short- and mid-term exposures, NO(2) and CO were positive across most periods, and O(3) was negatively associated with short- and mid-term exposures. Logistic regression analysis confirmed these findings, showing that short- and mid-term exposure to PM(10), PM(2.5), and SO(2) was negatively associated with the risk of belonging to the high-WBC group, while long-term exposure to PM(10), PM(2.5), NO(2), and CO showed positive associations with risk. Conclusions: 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.