Association between air pollutants and blood cell counts in pediatric patients with asthma: a retrospective observational study

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Asthma is a common respiratory disease in children, and air pollution is a risk factor for pediatric asthma. However, how air pollution affects blood cells in pediatric patients with asthma remains unclear. This retrospective observational study, performed in 2007–2018 at a medical center, enrolled non-trauma patients aged < 17 years who visited the emergency department and had asthma. Medical records and blood cell counts, including absolute neutrophil count (ANC), eosinophil count, and platelet count were extracted. The concentrations of PM 2.5 , PM 10 , sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ) were measured from 11 air-monitoring stations in Kaohsiung City. One-unit increases in PM 2.5 (regression coefficient: 25.618; S.E.: 5.937; p < 0.001), PM 10 (19.97; 3.541; p < 0.001), NO2 (70.681; 15.857; p < 0.001), SO 2 (81.694; 30.339; p = 0.007), and O 3 (23.42; 8.831; p = 0.022) on lag 0–6 (7 d average) correlated positively with ANC. One-unit increases in PM 2.5 (0.859; 0.357; p = 0.016), PM 10 (0.728; 0.213; p = 0.001), and SO 2 (4.086; 1.811; p = 0.024) on lag 0–6 correlated positively with eosinophil count. Additionally, one-unit increases in PM 2.5 (0.302; 0.101; p = 0.003) and PM 10 (0.229; 0.06; p < 0.001) on lag 0–6 correlated positively with platelet count. In a two-pollutant model, the impacts of PM 2.5 and PM C on ANC and platelet count remained statistically significant after adjusting for other air pollutants. Additionally, PM C correlated significantly with eosinophil count after adjusting for PM 2.5 , NO 2 , SO 2 , and O 3 . Quartile increases in PM 2.5 and PM C levels correlated positively with ANC, eosinophil count, and platelet count (all p for trend < 0.05). PM 2.5 , PM C , and NO 2 were independently and positively associated with ANC, PM C was positively associated with eosinophil count, and PM 2.5 and PM C were positively associated with platelet count in pediatric patients with asthma. Our results highlight the relationship between air pollution and blood cell counts in pediatric patients with asthma.