کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4438642 1620409 2012 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Extreme value analyses of VOC exposures and risks: A comparison of RIOPA and NHANES datasets
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علم هواشناسی
پیش نمایش صفحه اول مقاله
Extreme value analyses of VOC exposures and risks: A comparison of RIOPA and NHANES datasets
چکیده انگلیسی

Extreme value theory, which characterizes the behavior of tails of distributions, is potentially well-suited to model exposures and risks of pollutants. In this application, it emphasizes the highest exposures, particularly those that may be high enough to present acute or chronic health risks. The present study examines extreme value distributions of exposures and risks to volatile organic compounds (VOCs).Exposures of 15 different VOCs were measured in the Relationship between Indoor, Outdoor and Personal Air (RIOPA) study, and ten of the same VOCs were measured in the nationally representative National Health and Nutrition Examination Survey (NHANES). Both studies used similar sampling methods and study periods. Using the highest 5 and 10% of measurements, generalized extreme value (GEV), Gumbel and lognormal distributions were fit to each VOC in these two large studies. Health risks were estimated for individual VOCs and three VOC mixtures. Simulated data that matched the three types of distributions were generated and compared to observations to evaluate goodness-of-fit. The tail behavior of exposures, which clearly neither fit normal nor lognormal distributions for most VOCs in RIOPA, was usually best fit by the 3-parameter GEV distribution, and often by the 2-parameter Gumbel distribution. In contrast, lognormal distributions significantly underestimated both the level and likelihood of extrema. Among the RIOPA VOCs, 1,4-dichlorobenzene (1,4-DCB) caused the greatest risks, e.g., for the top 10% extrema, all individuals had risk levels above 10−4, and 13% of them exceeded 10−2. NHANES had considerably higher concentrations of all VOCs with two exceptions, methyl tertiary-butyl ether and 1,4-DCB. Differences between these studies can be explained by sampling design, staging, sample demographics, smoking and occupation.This analysis shows that extreme value distributions can represent peak exposures of VOCs, which clearly are neither normally nor lognormally distributed. These exposures have the greatest health significance, and require accurate modeling.


► Personal VOC exposures drawn from two studies, RIOPA and NHANES, were used.
► Generalized extreme value (GEV) and Gumbel distributions were fit to VOC extrema.
► The tail behavior of exposure was usually best fit by GEV and Gumbel distributions.
► Lognormal distributions underestimated both the level and likelihood of extrema.
► NHANES had considerably higher concentrations of most VOCs, including extrema.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Atmospheric Environment - Volume 62, December 2012, Pages 97–106
نویسندگان
, , ,