天津某老年社区夏冬季室内与个体暴露PM2.5对比

于2011年夏季(6月13日—7月2日)和冬季(11月30日—12月12日)在天津市某老年社区采集室内与老年人个体暴露PM_2.5样品,分析二者的质量浓度及化学组分特征. 结果表明:夏、冬季室内ρ(PM_2.5)分别为(138±103)和(173±136)μg/m3,二者差异显著(P<0.05)；冬季室内ρ(PM_2.5)、ρ(SO₄2-)和ρ(OC)显著高于夏季(P<0.05),初步推断是由于冬季燃煤取暖排放的大量颗粒物渗透进入室内所致；冬季室内源(如清扫和吸烟)对某些室内PM_2.5组分(Al、Ca和Cd)的贡献较夏季显著. 对个体暴露与室内ρ(PM_2.5)的相关性分析发现,二者在夏、冬季均显著相关(P<0.05). 在受试老年人时间活动模式基础上,采用COD(分歧系数)评估室内和个体暴露PM_2.5化学组成的相似度,结果显示,室内与个体暴露PM_2.5的COD在夏、冬季分别为0.34±0.10和0.37±0.12；冬季受试老年人在交通微环境所处时间较长,致使COD大于0.5的样本数所占比例较夏季高. 室内和老年人个体暴露PM_2.5的ρ(OC)/ρ(EC)在夏、冬季均相近,说明二者的碳组分来源相似. 

Comparison of Residential Indoor and Personal Exposure to PM2.5 during Summer and Winter in an Elderly Community in Tianjin

To investigate the characteristics of residential indoor and personal exposure to PM_2.5, samples of two types of PM_2.5 for elderly participants were collected in an elderly community in Tianjin during summer (from June 13th to July 2nd) and winter (from November 30th to December 12th) in 2011. Subsequently, chemical compositions were analyzed. The results showed that the mass concentration of indoor PM_2.5 was (138±103) μg/m3 in summer and (173±136) μg/m3 in winter, with significant seasonal differences (P<0.05). The indoor PM_2.5, SO₄2- and OC mass concentrations were significantly higher in winter than those in summer (P<0.05), due to coal combustion for domestic heating in winter. The contributions of indoor sources to some of the indoor PM_2.5 compositions (Al, Ca, and Cd) were higher in winter than in summer. The mass concentrations of personal exposure to PM_2.5 were significantly correlated with those of indoor PM_2.5 in both summer and winter, and were not significantly different between the two types of PM_2.5 (P>0.05). In addition, the coefficient of divergences (COD) was used to compare the chemical compositions between indoor and personal exposure to PM_2.5 based on time activity patterns for elderly participants. The results showed that the COD of indoor-personal exposure PM_2.5 was 0.34±0.10 and 0.37±0.12 in summer and winter, respectively. The percentage of indoor-personal exposure samples with COD values over 50% in winter was higher than in summer. The ratio of OC/EC of indoor PM_2.5 was similar with that of personal exposure to PM2.5 in both summer and winter, indicating similar sources of carbon materials for indoor and personal exposure to PM_2.5.