Effects of gaseous air pollutants on blood routine indicators in elders from a community in Beijing

[Background] In recent years, research about effects of gaseous air pollutants on population health has continued to make progress, but evidence for the impacts on peripheral hematology is still limited. [Objective] This study is designed to investigate the effects of exposures to main gaseous air pollutants [carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), and sulfur dioxide (SO2)] on blood routine indicators of elderly residents. [Methods] From January 2018 to September 2019, blood routine tests, basic information surveys, and environmental exposure data collection were performed on 427 people aged 50 to 78 years in a community of Beijing. Univariate linear regression models were used to explore the potential risk factors of blood routine indicators. Single-pollutant multivariate linear regression models were established to analyze the effects of gaseous pollutants on blood routine indicators. Effect modification models and two-pollutant multivariate linear regression models were conducted to explore the robustness of the results from the single-pollutant models. [Results] The medians [interquartile ranges (IQR)] of white blood cells, red blood cells, and platelets of the study subjects were 5.7×109 (1.7×109), 4.6×1012(0.5×1012), and 217.0×109 (63.5×109) L-1, respectively. Along with the increases in SO2, neutrophils percentage showed significant decreases (P < 0.05), while lymphocytes percentage showed significant increases (P < 0.05). Red blood cells counts, mean corpuscular hemoglobin and its concentration showed significant decreases (P < 0.05), whereas mean corpuscular volume and red cell distribution width standard deviation showed significant increases (P < 0.05) along with increases of the four pollutants. An IQR increment in CO (0.4mg·m-3), NO2 (24.4 μg·m-3), O3 (67.1 μg·m-3), and SO2 (3.4 μg·m-3) at 90-d moving average was significantly associated with percent changes of -2.6% (95%CI: -3.7%--1.4%), -2.6% (95%CI: -4.0%--1.2%), -3.2% (95%CI: -4.8%--1.5%), and -2.9% (95%CI: -3.9% --1.9%) (all P < 0.01) in mean corpuscular hemoglobin concentration, respectively. Along with the increases in CO, NO2, and SO2, platelet count, mean platelet volume, and platelet hematocrit showed decreasing trends (P < 0.05), while platelet distribution width showed an increasing trend (P < 0.05). An IQR increment in CO, NO2, and SO2 at 90-d moving average was significantly associated with percent changes of -21.2% (95% CI: -29.3% - -12.2%), -19.7% (95% CI: -29.3% - -8.8%), and -15.6% (95% CI: -23.2% - -7.2%) (all P < 0.01) in platelet hematocrit, respectively. No significant effect modification was observed when the data were stratified by cold, passive smoking, chronic diseases such as hypertension and diabetes, and medication use (P≥0.10). The results of the two-pollutant models controlling for other gaseous air pollutants and fine particulate matters at the same time window were generally consistent with those of the single-pollutant models. [Conclusion] Exposure to gaseous air pollutants may lead to quantitative and morphological changes in white blood cells, red blood cells, and platelets.