Particle Exposure Assessment for Community Elderly (PEACE) in Tianjin, China was to characterize personal PM10 exposure, and provide data support for an epidemiological study investigating potential health effects of PM pollution on Chinese elderly population. In this study, a total of 80 elderly participants were recruited for a two-consecutive-day personal exposure measurement, and simultaneously residential indoor, residential outdoor and community PM10 were monitored in the summer and winter of 2009. Personal PM10 concentrations were 192.8 ± 100.6 μg m−3 in summer and 154.6 ± 105.4 μg m−3 in winter. Modeled personal exposures were less than measured personal exposures while a high coefficient of determination (R2) of 0.71 was obtained. Based on measured and modeled exposures, a mean personal cloud of 30.2 μg m−3 was estimated in summer and 16.5 μg m−3 in winter. Moderate correlation emerged between personal and community PM10 concentrations in summer (r = 0.39), and stronger correlation was found in winter (r = 0.82). Analysis of variance (ANOVA) shown that smoking, cooking and cleaning activities did not produce significant effect on personal exposures. Further more, multivariate regression analysis performed in this study revealed that community PM10 level contributed most of personal PM10 exposure, 32% in summer and 64% in winter, respectively. The findings of this study indicated that PM10 personal exposures were considerably influenced by outdoor particulate matter rather than typical indoor sources, and ambient PM10 level measured at community monitoring sites may be used as a surrogate of personal exposure to PM10.
The influence of second-generation products on the particle mass yield of beta-caryophyllene ozonolysis was systematically tested and quantified. The approach was to vary the relative concentrations of first- and second-generation products by adjusting the concentration of ozone while observing changes in particle mass yield. For all wall-loss corrected organic particle mass concentrations M-org of this study (0.5 < M-org < 230 mu g m(-3)), the data show that the particle-phase organic material was composed for the most part of second-generation products. For 0.5 < M-org < 10 mu g m(-3), a range which overlaps with atmospheric concentrations, the particle mass yield was 10 to 20% and was not sensitive to ozone exposure, implying that the constituent molecules were rapidly produced at all investigated ozone exposures. In contrast, for M-org > 10 mu g m(-3) the particle mass yield increased to as high as 70% for the ultimate yield corresponding to the greatest ozone exposures. These differing dependencies on ozone exposure under different regimes of M-org are explained by a combination of the ozonolysis lifetimes of the first-generation products and the volatility distribution of the resulting second-generation products. First-generation products that have short lifetimes produce low-volatility second-generation products whereas first-generation products that have long lifetimes produce high-volatility second-generation products. The ultimate particle mass yield was defined by mass-based stoichiometric yields alpha(i) of alpha(0) = 0.17 +/- 0.05, alpha(1) = 0.11 +/- 0.17, and alpha(2) = 1.03 +/- 0.30 for corresponding saturation concentrations of 1, 10, and 100 mu g m(-3). Terms alpha(0) and alpha(1) had low sensitivity to the investigated range of ozone exposure whereas term alpha(2) increased from 0.32 +/- 0.13 to 1.03 +/- 0.30 as the ozone exposure was increased. These findings potentially allow for simplified yet accurate parameterizations in air quality and climate models that seek to represent the ozonolysis particle mass yields of certain classes of biogenic compounds.