Indoor Exposure to "Outdoor PM10" Assessing Its Influence on the Relationship Between PM10 and Short-term Mortality in US Cities

From the aDepartment of Building Science, School of Architecture, Tsinghua University, Beijing, China
Epidemiology (Cambridge, Mass.) (Impact Factor: 6.2). 09/2012; 23(6):870-8. DOI: 10.1097/EDE.0b013e31826b800e
Source: PubMed


: Seasonal and regional differences have been reported for the increase in short-term mortality associated with a given increase in the concentration of outdoor particulate matter with an aerodynamic diameter smaller than 10 μm (PM10 mortality coefficient). Some of this difference may be because of seasonal and regional differences in indoor exposure to PM10 of outdoor origin.
: From a previous study, we obtained PM10 mortality coefficients for each season in seven U.S. regions. We then estimated the change in the sum of indoor and outdoor PM10 exposure per unit change in outdoor PM10 exposure (PM10 exposure coefficient) for each season in each region. This was originally accomplished by estimating PM10 exposure coefficients for 19 cities within the regions for which we had modeled building infiltration rates. We subsequently expanded the analysis to include 64 additional cities with less well-characterized building infiltration rates.
: The correlation (r = 0.71 [95% confidence interval = 0.46 to 0.86]) between PM10 mortality coefficients and PM10 exposure coefficients (28 data pairs; four seasons in each of seven regions) was strong using exposure coefficients derived from the originally targeted 19 National Morbidity, Mortality, and Air Pollutions Study cities within the regions. The correlation remained strong (r = 0.67 [0.40 to 0.84]) when PM10 exposure coefficients were derived using 83 cities within the regions (the original 19 plus the additional 64).
: Seasonal and regional differences in PM10 mortality coefficients appear to partially reflect seasonal and regional differences in total PM10 exposure per unit change in outdoor exposure.

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Available from: Bin Zhao, Mar 13, 2015
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    • "Most studies used ambient air pollution data obtained from central monitoring stations as a surrogate for total exposure to ambient air pollutants (Brauer et al., 2001; Lagorio et al., 2006; Peacock et al. 2001; Silkoff et al., 2005; Trenga et al., 2006). However, total exposure to ambient (outdoor) PM should include direct outdoor exposure and indoor exposure to outdoor-infiltrated PM, which may be influenced by many factors such as indoor/outdoor time ratios of people, air change rates, penetration factor, and so on (Chen et al., 2013; Hsu et al., 2012). It is not clear whether the outdoor PM exposure and the outdoororiginated equivalent personal PM exposures may be associated with the same health effects. "
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    ABSTRACT: BACKGROUND: The use of ambient air pollution data obtained from central air-monitoring stations as surrogates for participants' exposures to outdoor air pollutants in previous studies may have introduced bias in the estimation of exposure-response associations. OBJECTIVES: We investigated and compared the effects of short-term exposure to outdoor particulate matter (PMout) and outdoor-originated equivalent personal PM (PMeq) on lung function in chronic obstructive pulmonary disease (COPD) patients. METHODS: A total of 33 doctor-diagnosed stable COPD patients were recruited and repeatedly measured for lung function (totally 170 measurements) in 2013-2014. Daily PMout concentrations were obtained from central-monitoring stations, and daily time-weighted average PMeq concentrations were estimated based on PMout over the study. Associations of PM with lung function were estimated using mixed-effects models. RESULTS: Interquartile range increases in PM2.5out (111.0μg/m3, 5-day) and PM10out (112.0μg/m3, 3-day) were associated with a 3.3% (95% confidence interval [CI]: -5.8%, -0.8%) reduction and a 2.1% (95%CI: -3.9%, -0.3%) reduction in forced vital capacity (FVC), respectively. Similar results were found for forced expiratory volume in 1s (FEV1). An interquartile range increase in PM2.5eq (45.3μg/m3, 3-day), but not PM10eq, was still associated with a 1.7% (95%CI: -3.3%, -0.1%) reduction in FVC. CONCLUSIONS: Our study may provide a novel approach to assess the association of ambient PM with health observations with improved accuracy.
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    • "It is a critical aspect of air pollution exposure assessment as it influences the import of outdoor-generated air pollutants and the export of indoorgenerated air pollutants. Chen et al. [6] [7] showed that variance in the air change rates of different regions could partially explain the inter-regional variance in health risks to both ozone and particulate matter. Considering the fact that people spend majority of their time in residences [8] [9], an evaluation of the air change rate of residences in Beijing is required to assess its population's exposure to air pollution. "
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    ABSTRACT: Air change rate is a very important parameter for indoor air quality estimation as it influences the exchange of air pollutants between indoor and outdoor environments. Consequently, determining air change rate distribution is indispensable for assessment of a population’s exposure to air pollutants. In this study, the annual and seasonal average infiltration rates (air change rate for window close conditions) of 180 representative residences were simulated using the multi-zone network airflow model (CONTAM) to understand the residential infiltration rate distributions in Beijing. The representative residences were selected by probability sampling based on building characteristics, including building type, floor area, number of rooms, construction year, number of floors, and building orientation. The results show that the annual average infiltration rates in Beijing range from 0.02 to 0.82 h-1 with a median value of 0.16 h-1. The empirical distributions of the annual and seasonal average residential infiltration rates in Beijing were provided. The annual average infiltration rates were also found to well fit a two-parameter lognormal distribution, the median and standard deviation of which is -1.79 and 0.62. Infiltration rates of 34 residences in Beijing were measured via the CO2 decay method, and the measured infiltration rates of residences matched the simulated distributions well. The differences between the simulated and measured infiltration rates are discussed.
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    • "It turned out that total exposure can partially reflect the intercity difference of ozone mortality coefficient, implying that total exposure, considering the difference between indoor and outdoor, is more reasonable to assess health risks than atmospheric pollutants concentrations. This conclusion has also been validated for PM10 (particles with aerodynamic diameter smaller than 10 μm) by Chen et al. (2012b). The USA and Canada has conducted nationwide surveys, CAPS (Wiley et al., 1991a, 1991b), CHAPS (Leech et al., 1996, 1999) and NHAPS (Klepeis et al., 2001), of time-activity pattern from 1980s. "
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    ABSTRACT: Air pollution has become a striking problem in recent years. When estimating the degree of human exposure to a particular air pollutant, time-activity pattern is one of the most important factors, which is able to quantify the time people spend in different micro-environments, such as indoor and outdoor. Traditional surveys use the method of questionnaires and telephone calls to explore the time-activity pattern. In this paper, we propose a novel method to analyse the time-activity pattern by utilising mobile web usage log. We test the method on two datasets covering about four million users. Experiments show that our method achieves an acceptable performance, and can truly measure the time-activity pattern of human beings.
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