摘要目的 研究极端天气条件下室内空气中细颗粒物(PM2.5)浓度水平及其特征.方法 选择2013年1月份连续雾霾及2月份春节燃放烟花爆竹期间,在北京市CDC,考虑空间垂直和水平距离,以及窗户密封性和室内人为活动量,分别在室内和室外各设置3个监测点.采用膜采样和实验室重量法,连续监测室内外空气中PM2.5质量浓度,同时收集气象资料.结果 室内总体PM2.5浓度中位数(四分位数)为87.76(52.05 ～ 174.48) μg/m3,低于室外[128.79(95.14 ～ 221.88) μg/m3,Z=-4.126,P＜0.01].室内3个监测点间浓度差异有统计学意义(x2=23.09,P＜0.01),窗户密封差的监测点B浓度最高[94.05(63.46～ 189.17) μg/m3],其次是有人员活动的监测点A[87.76 (43.54～159.86) μg/m3],密封好及人员活动少的监测点C浓度最低[77.89(51.19 ～ 144.40)μg/m3].雾霾期间室内PM2.5浓度[273.22 (223.44～ 308.47) μg/m3]高于室内总体浓度水平(Z=-5.20,P＜0.01)；燃放鞭炮期间PM25浓度[167.90(129.15 ～ 187.90) μg/m3]高于春节期间(7 d)室内浓度水平[72.76(36.97～ 145.30) μg/m3,Z=-2.34,P＜0.05],同时高于室内总体水平(Z=-1.98,P＜0.05),但低于雾霾天气浓度水平(Z=-3.43,P＜0.01).所有室内质量浓度与室外质量浓度的比值(I/O比值)中除4个值在1.00～1.09外,其余都小于1.00,其中监测点B的I/O比值(0.69 ±0.21)＞监测点A(0.64±0.23)＞监测点C(0.58 ±0.18) (F =22.85,P＜0.01),而且雾霾期间I/O比值(0.87±0.14)＞燃放鞭炮(0.68±0.08)＞日平均浓度小于75μg/m3的晴好天气(0.51±0.18) (F =29.88,P ＜0.05).降雪或刮3级以上风可以使大气中PM2.5浓度降至谷值,而I/O比值在连日刮3级以上风时才会达到谷底值.当雾霾天气缓解或消失后,室外带入室内的PM2.5会滞留1～2d.结论 室内空气中PM2.5浓度随室外浓度增加而增加,雾霾和燃放鞭炮会导致室内空气质量严重下降,并随室外空气质量的改善具有滞后性.

abstractsObjective To study the concentration level and characteristics of indoor particle matter ≤2.5 μm in aerodynamic diameter (PM2.5) under extreme weather condition.Methods During the period of haze in January 2013 and the fireworks and firecracker setting off in the Spring Festival of February 2013,three monitoring sites located indoor and outdoor were respectively selected by Beijing CDC,considering the vertical and horizontal distance,windows tightness and human activity indoor.PM2.s samples were collected by filters and measured by laboratory weight method.At the same time,the meteorological data was also collected.Results The median (quartiles) of overall concentration level of indoor PM2.5 was 87.76 μg/m3 (52.05-174.48 μg/m3) and was lower than that of outdoor PM2.5 (128.79 μg/m3,95.14-221.88 μg/m3 ; Z =-4.13,P ＜ 0.01).The concentration of three indoor monitoring sites was different(x2 =23.09,P ＜ 0.01).The PM2.5 concentrations of monitoring point B in poor sealing window was the highest (94.05 μg/m3 ; 63.46-189.17 μg/m3) and point C in sealed and less human activity,which was the lowest (77.89 μg/m3,51.19-144.40 μg/m3).The concentration level of indoor PM2.5 in the haze period (273.22 μg/m3,223.44-308.47 μg/m3) was higher than the overall concentration level of indoor PM2.5 (Z =-5.20,P ＜ 0.01).The concentration level of indoor PM2.5 in the fireworks and firecracker period (167.90 μg/m3,129.15-187.90 μg/m3) was higher than that in the Spring Festival period (7 days,72.76 μg/m3,36.97-145.30 μg/m3,Z =-2.34,P ＜ 0.05) and the overall concentration level of indoor PM2.5 (Z =-1.98,P ＜ 0.05) ; however,it was lower than the concentration level of indoor PM2.5 in the haze period (Z =-3.43,P ＜ 0.01).The I/O ratio (indoor concentration/outdoor concentration) was all less than 1.00 except 4,which was between 1.00-1.09.The mean I/O ratio in monitoring site B,monitoring site A and monitoring site C was 0.69 ±0.21,0.64 ±0.23 and 0.58 ±0.18,respectively,show significant bias (F =22.85,P ＜ 0.01).During the period of haze,the fireworks and firecracker and fine weather (when ambient PM2.5 concentration was lower than the standard value of 75 μg/m3),the mean I/O ratio was 0.87 ± 0.14,0.68 ± 0.08 and 0.51 ± 0.18,respectively,showing significant bias (F =29.88,P ＜ 0.05).Under conditions of snow and high wind speed (≥ 3.4 m/s),PM2.5 concentration decreased to the valley point.The valley value of I/O ratio only occurred after several days of high windy weather.Moreover,the PM2.5 concentration level of indoor air showed a delayed 1-2 days after the haze weakened or disappeared.Conclusion Mass concentration of indoor PM2.5 increased significantly with increases of outdoor concentration.Haze and setting off fireworks/firecracker could lead to a serious decline of indoor air quality (IAQ),and the improvement of IAQ was lagging behind the outdoor changes.