Acute changes in a respiratory inflammation marker in guards following Beijing air pollution controls

The adverse respiratory health effects of PM_2.5 have been studied. However, the epidemiological evidence for the association of specific PM_2.5 sources with health outcomes is still limited. This study investigated the association between PM_2.5 components and sources with a biomarker of acute respiratory inflammation (FeNO) in guards. Personal exposure was estimated by microenvironment samplers and FeNO measurements were carried out before, during and after the Victory Day Military Parade in Beijing. Four sources were determined by factor analysis, including urban pollution, dust, alloy steel abrasion and toxic metals. A mixed-effect model was used to estimate the associations of FeNO with PM_2.5 sources and chemical constituents, controlling for age, BMI, smoke activity, physical activity, waist circumference, temperature and relative humidity. In summary, large concentration decreases in PM_2.5 concentration and PM_2.5 chemical constituents were observed in both roadside and indoor environments during the air control periods, immediately followed by statistically significant decreases in FeNO of roadside guards and patrol guards. Besides, statistically significant increases in FeNO were found to be associated with interquartile range (IQR) increases in some pollutants, with an increase of 1.45ppb (95% CI: 0.69, 2.20), 0.65ppb (95% CI: 0.13, 1.17), 1.48ppb (95% CI: 0.60, 2.35), 0.82ppb (95% CI: 0.44, 1.20), 0.77ppb (95% CI: 0.42, 1.11) in FeNO for mass, sulfate, BC, Ca²⁺ and Sm, respectively. In addition, compared to alloy steel abrasion and toxic metals, urban pollution and dust factors were more associated with acute airway inflammation for highly-exposed populations.