ABSTRACT
Fine particle pollution is still a severe issue in the northwestern region of China where the formation mechanism of which remains ambiguous due to the limited studies there. In this study, a comprehensive study on the chemical composition and sources of PM2.5 at an ex-heavily polluted northwestern city was conducted, based on filter sampling data obtained from three consecutive winter campaigns during 2020-2022. The average PM2.5 during the three winter campaigns were 170.9 ± 66.4, 249.0 ± 75.7, and 200.9 ± 47.6 µg/m3, respectively, with the daily maximum value of PM2.5 exceeds 400 µg/m3 under stagnant meteorological conditions charactered by high relative humidity (>60 %) and low wind speed (<1 m/s). The major chemical components in PM2.5 were found to be inorganic aerosol (55.2 %) that mainly constituted by sulfate (24.2 %), and mineral dust (14.9 %); while the carbonous species contributed a minor fraction (â¼13 %). In addition, (NH4)2SO4 and NH4NO3 were the dominate contributors to appearance of low visibility (<3 km) which together accounting for over 85 % of light extinction coefficient (bext) during heavy polluted period. Source appointment of fine particles was then conducted by applying the positive matrix factorization method, and the primary sources were resolved to be coal combustion (27.7 %) and biomass burning (18.6 %), followed by industrial dust (16.2 %), residential combustion (15.3 %), traffic emissions (11.9 %) and dust aerosol (10.4 %). To explore the potential formation mechanism of fine particle pollution, the chemical evolution pattern combined with gaseous pollutants and meteorological parameters were further analyzed, which refine the important role of primary emissions in the forming of high sulfate aerosol loading, while secondary formation was largely suppressed during the winter period that totally different from those reported in the developed regions of China, thus indicating more effort should be paid on the reduction of primary particles emissions in the northwestern cities than on its gaseous percussors.
ABSTRACT
BACKGROUND: Glycopyrronium is a once-daily (od) long-acting muscarinic antagonist for the maintenance treatment of chronic obstructive pulmonary disease (COPD). The GLOW7 study evaluated the efficacy and safety of od glycopyrronium 50 µg in predominantly Chinese patients with moderate-to-severe COPD. METHODS: In this 26-week, multi-center, double-blind, placebo-controlled, parallel-group study, men and women ≥40 years with moderate-to-severe COPD were randomized to glycopyrronium 50 µg od or placebo (2:1). The primary objective was to confirm the significant improvement of trough forced expiratory volume in 1 second (FEV1) following 12 weeks of treatment with glycopyrronium compared with placebo. Secondary objectives included the effect of glycopyrronium on health status (St George's Respiratory Questionnaire), breathlessness (Transition Dyspnea Index), other lung function parameters, rescue medication use, and COPD exacerbations. Safety and tolerability were also evaluated. RESULTS: Of the 460 patients randomized, 459 were included in the full analysis set (glycopyrronium, n=306; placebo, n=154; mean age 64.7 years; mean post-bronchodilator FEV1: 50.8% predicted); 425 (92.4%) completed the study. At Week 12, glycopyrronium signifcantly improved trough FEV1 with a least square means treatment difference of 141 mL (95% confidence interval 111 mL, 171 mL; P<0.001) compared with placebo. The mean treatment effect of glycopyrronium was greater than the minimum clinically important difference versus placebo in both St George's Respiratory Questionnaire total score (-4.92; P<0.001) and Transition Dyspnea Index focal score (1.0; P<0.001) at week 26. Glycopyrronium reduced the risk of exacerbations in terms of time to first moderate or severe exacerbation by 28% (P=0.153) and rate of moderate or severe COPD exacerbation by 29% (P=0.119) compared with placebo. Incidence of death was 1.3% with glycopyrronium and 0% in placebo during the treatment period. Overall incidence of adverse events (glycopyrronium 43.6%; placebo 47.4%) and serious adverse events (glycopyrronium 5.6%; placebo 9.1%) were similar. CONCLUSION: In predominantly Chinese patients with moderate-to-severe COPD, od glycopyrronium 50 µg significantly improved lung function, dyspnea, and health status compared with placebo. The safety and tolerability profile of glycopyrronium was comparable to placebo.
