Monitoring metrics for short-term exposure to ambient ozone and pulmonary function and airway inflammation in healthy young adults / 北京大学学报(医学版)

OBJECTIVE@#To assess the associations of different monitoring metrics for short-term exposure to ambient ozone (O3) with pulmonary function and airway inflammation in healthy young adults.@*METHODS@#A total of 97 healthy young college students were recruited and followed in a panel study conducted from December 2017 to June 2018. Each participant underwent 3 follow-up visits, and lung function and fractional exhaled nitric oxide (FeNO) were measured at each visit. Ambient air pollutant concentrations were obtained from the environment monitoring station of Beijing closest to the participant residences, and meteorological data were collected from China Meteorological Data Service Center. Linear mixed-effect models were applied to assess the associations between different monitoring metrics for ambient O3 short-term exposure with pulmonary function or airway inflammation in the healthy young adults.@*RESULTS@#During the study period, the P50 (P25, P75) values for ambient O3 concentration expressed as daily 1-hour maximum (O3-1 h max), daily maximum 8-hour average (O3-8 h max) and 24-hour average (O3-24 h avg) were 102.5 (76.8, 163.0) μg/m3, 91.1 (68.3, 154.3) μg/m3 and 61.6 (36.9, 81.7) μg/m3, respectively. The different monitoring metrics for short-term exposure to ambient O3 were significantly associated with reduced forced expiratory volume in the first second (FEV1) and increased FeNO. An interquartile range (IQR) increase in 6-d moving average of O3-1 h max (IQR=71.5 μg/m3) was associated with a 6.2% (95%CI: －11.8%, －0.5%) decrease in FEV1 and a 63.3% (95%CI: 13.8%, 134.3%) increase in FeNO. An IQR increase in 7-d moving average of O3-8 h max (IQR=62.0 μg/m3) was associated with a 6.2% (95%CI: －11.6%, －0.7%) decrease in FEV1and a 75.5% (95%CI: 19.3%, 158.0%) increase in FeNO. An IQR increase in 5-d moving average of O3-24 h avg (IQR=32.9 μg/m3) was associated with a 3.7% (95%CI: －7.1%, －0.2%) decrease in FEV1and a 25.3% (95%CI: 3.6%, 51.6%) increase in FeNO. There was no significant association between the three monitoring metrics for O3 exposure and peak expiratory flow (PEF).@*CONCLUSION@#Short-term exposure to ambient O3 was associated with decreased lung function and increased airway inflammation among the healthy young adults, and daily 1-hour maximum was more sensitively to the respiratory effects of O3.

Effects of high-efficiency particulate air purifiers on indoor fine particulate matter and its constituents in a district of Beijing during winter / 北京大学学报(医学版)

OBJECTIVE@#To analyze the effect of domestic high-efficiency particulate air (HEPA) purifiers on the concentrations of indoor fine particulate matter (PM2.5) and its elementary constituents in 20 residences in a district of Beijing during winter.@*METHODS@#From November 2015 to January 2016, 20 residences in a district of Beijing were selected, where indoor and outdoor PM2.5 data were collected simultaneously in three time periods according to the operating of air purifiers (Group 0 h: 24 hours before operating; Group 24 h: 24 hours after operating; Group 48 h: 24 to 48 hours after operating). The content of 21 elements in PM2.5 samples were determined by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). Indoor/outdoor particle concentration ratio (I/O ratios) and ΔI/O ratios were used to describe the pollution levels and the variation range of PM2.5 and its 21 elementary constituents. One-way analysis of variance (ANOVA) for repeated measurement data was applied to compare the I/O ratios of PM2.5 and its elementary constituents among the different groups, and Bonferroni method was used for comparison in pairs. Wilcoxon signed rank test for paired-samples was used to compare ΔI/O ratios of 21 elementary constituents with that of PM2.5.@*RESULTS@#The median I/O ratios of PM2.5 in the three groups were 1.27 (P25-P75: 0.50-2.68), 0.45 (P25-P75: 0.27-1.03) and 0.36 (P25-P75: 0.28-2.48), respectively. Compared with Group 0 h, the I/O ratios of PM2.5 in Group 24 h (P=0.042) and Group 48 h (P=0.006) decreased significantly. However, there was no significant difference between Group 24 h and Group 48 h. Significant differences were found comparing ΔI/O ratios of aluminium, ferrum and titanium to that of PM2.5, in both Group 24 h and Group 48 h (P<0.05). No significant change was found in the I/O ratios of these three elements among the three groups before and after air purifier operating (P>0.05). Distances from residences to traffic arteries could affect I/O ratios of some elements from traffic-related source (P<0.05).@*CONCLUSION@#Domestic HEPA air purifiers could effectively reduce indoor PM2.5 concentration, and the pollution level of PM2.5 tend to be stable after the purifier operating for a time. The purifiers had different effects on different elements, among which most showed statistical significances.