This study aimed to assess the differential effects of size-specific PM (PM2.5, PM10-2.5, and PM10) on daily outpatients for Lower Respiratory Infection (LRI), Pneumonia, and Bronchitis among children in Lanzhou, China. A distributed lag nonlinear model (DLNM) was employed to evaluate the non-linear and delayed effects. The models were fitted with different lag structures, including single lag days from the current to the previous seven days (lag0 to lag7) and moving average concentrations over seven lag days (lag0-1 to lag0-7). We found that different PM fractions were significantly associated with hospital visits for LRI, pneumonia, and bronchitis, and cumulative effects increased with the increasing number of lag days investigated. Relative risk (RR) of LRI outpatient visits among children per 10 mu g/m3 increase in PM2.5, PM10-2.5, and PM10 were 1.070 (95% CI: 1.059, 1.081), 1.010 (95% CI: 1.006, 1.015), and 1.013 (95% CI: 1.010, 1.016), respectively. For every 10 mu g/m3 increase in PM2.5, PM10-2.5, and PM10, the RR values for pneumonia were 1.081, 1.013, and 1.019, and those for bronchitis were 1.069, 1.009, and 1.012, respectively. Boys and children aged 0-3 years were more sensitive to PM exposure. We also found significantly higher effects of PM in cold seasons than that in warm seasons. Our results suggested that short-term exposure to size-specific PM, PM2.5 in particular, might be an important trigger of outpatient visits for overall and cause-specific LRI.

Until now, the epidemiological evidence on the association between short-term exposure to ambient carbon monoxide (CO) and cardiovascular diseases (CVDs) is relatively lacking and controversial. This study aims to examine the relationship between ambient CO and daily emergency room visits (ERVs) for total and cause-specific CVD in Lanzhou, China. A distributed lag nonlinear model was used to examine the association. For every 1 mg/m3 increase in the CO concentration, the relative risks of daily ERVs were 1.041 (95

At present, evidence of the associations between carbon monoxide (CO) and respiratory diseases (RD) in Northwest China is limited and controversial. The aim of this study is to evaluate the impact of ambient CO on outpatient visits for RD in Lanzhou, China. The daily amount of outpatient visits for total and cause-specific RD, air pollutant, and weather variables were collected in Lanzhou, China from 1st January 2013 to 31st December 2019. A generalized additive model and distributed lag nonlinear model were used to assess associations between CO and outpatient visits for RD. During the study period, a total of 1,623,361 RD outpatient visits were recorded. For each interquartile range (IQR) (0.77 mg/m3) increase in CO, the relative risk (RR) was 1.163 (95