目的：分析使用家用高效空气过滤净化器（HEPA净化器）对北京市冬季某区居民住宅室内PM2.5浓度及其各元素组分的影响。方法：于2015年11月至2016年1月间选择北京市某区20户居民住宅，分别于空气净化器开启前后3个时间阶段（0 h组：开启前24 h；24 h组：开启后24 h；48 h组：开启后24~48 h）同步收集室内外PM2.5，采用电感耦合等离子体质谱法及等离子体发射光谱法测定PM2.5样品中21种元素含量，用室内外污染物浓度比值（indoor/outdoor ratio， I/O比值）与ΔI/O比值描述PM2.5及其组分的污染水平和变化幅度，采用单因素重复测量方差分析比较净化器开启前后不同组别PM2.5及其组分的I/O比值变化，Bonferroni法进行组间比较，采用配对样本比较的Wilcoxon符号秩检验方法比较PM2.5与各元素组分的ΔI/O比值。结果：3组PM2.5的I/O比值中位数分别为1.27（P25~P75：0.50~2.68）、0.45（P25~P75：0.27~1.03）和0.36（P25~P75：0.28~2.48）。与0 h组相比，24 h组（P=0.042）和48 h组（P=0.006）的I/O比值均显著下降，但24 h组和48 h组之间差异无统计学意义；24 h组和48 h组中，Al、Fe、Ti 3种元素的ΔI/O比值与PM2.5的ΔI/O比值差异有统计学意义（P<0.05），且此3种元素I/O比值随净化器开启时间阶段变化不显著（P>0.05）。结论：家用HEPA净化器能够有效降低室内PM2.5浓度，PM2.5浓度在净化器开启一定时间后趋于稳定，空气净化器对PM2.5不同元素组分影响不同，对大部分元素效果显著。

Objective： To analyze the effect of domestic high-efficiency particulate air (HEPA) puri-fiers 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 consti-tuents 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 significances.