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

Abstract

Background 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. Methods 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, PM₁₀, sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and ozone (O₃) were measured from 11 air-monitoring stations in Kaohsiung City. Results One-unit increases in PM_2.5 (regression coefficient = 0.098; S.E. =5.937; p < 0.001), PM₁₀ (regression coefficient = 0.129; S.E. =3.541; p < 0.001), NO₂ (regression coefficient = 0.110; S.E. =15.857; p < 0.001), SO₂ (regression coefficient = 0.049; S.E. =30.339; p = 0.007), and O₃ (regression coefficient = 0.048; S.E. =8.831; p = 0.022) on lag 0–6 (7 d average) correlated positively with ANC. One-unit increases in PM_2.5 (regression coefficient = 0.055; S.E. =0.357; p = 0.016), PM₁₀ (regression coefficient = 0.078; S.E. =0.213; p = 0.001), and SO₂ (regression coefficient = 0.041; S.E. =1.811; p = 0.024) on lag 0–6 correlated positively with eosinophil count. Additionally, one-unit increases in PM_2.5 (regression coefficient = 0.068; S.E. =0.101; p = 0.003) and PM₁₀ (regression coefficient = 0.086; S.E. =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, NO₂, SO₂, and O₃. Quartile increases in PM_2.5 and PM_C levels correlated positively with ANC, eosinophil count, and platelet count, with differences of approximately 13.8% and 16.2%, 18.5% and 17.3%, and 4.4% and 4.6% between the upper and lower quartiles, respectively. Conclusions PM_2.5, PM_C, and NO₂ 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 impact of air pollution on immunity and coagulation in pediatric patients with asthma.