Lung function decline associated with individual short-term exposure to PM1, PM2.5 and PM10 in patients with allergic rhinoconjunctivitis

Background: The susceptibility of allergic rhinoconjunctivitis (ARC) patients to air pollution has yet to be clarified. Objectives: Based on a repeated measurement panel study, we explored the association of short-term PM exposure with lung function in ARC patients and to further identify the susceptible populations.Methods: Personal PM exposure, including PM1, PM2.5 and PM10, was monitored consecutively for three days before outcomes measurements. Lung function indices including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), and forced expiratory flow at 25-75 % of the vital capacity (FEF25-75) were measured. Serum total immunoglobulin E (IgE), specific-allergen IgE, blood eosinophil and basophils, and the symp-toms severe scores were tested in each visit. Linear mixed effect models were applied to estimate the association be-tween PM exposure and lung function. Furthermore, stratified and overlapping grouped populations based on IgE levels were implemented to characterize the modification role and the modulating threshold of IgE at which the asso-ciation turned significantly negative.Results: Short-term PM personal exposure was associated with a significant decrease in lung function in ARC patients, especially for small airway respiratory indexes. The highest estimates occurred in PM1, specifically a 10 mu g/m3 increase reduced FEV1/FVC, PEF and FEF25-75 by 1.36 % (95 %CI: -2.29 to -0.43), 0.23 L/s (95 %CI: -0.42 to -0.03) and 0.18 L/s (95 %CI: -0.30 to -0.06), respectively. Notably, PM-induced decreases in lung function were stronger in patients with higher IgE levels (IgE <= 100 IU/mL), which were related to higher inflammatory cytokines and symp-toms scores. Further, PM-associated lung function declines enhanced robustly and monotonically with increasing IgE concentration. Potential modulating thresholds of IgE occurred at 46.8-59.6 IU/mL for significant PM-lung function associations.Conclusion: These novel findings estimated the short-term effects of PM on lung function in ARC patients, and the threshold values of IgE for the significant and robust associations.