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Evaluating differences between measured personal exposures to volatile organic compounds and concentrations in outdoor and indoor air.

Authors
Sexton-K; Adgate-JL; Mongin-SJ; Pratt-GC; Ramachandran-G; Stock-TH; Morandi-MT
Source
Environ Sci Technol 2004 May; 38(9):2593-2602
NIOSHTIC No.
20037399
Abstract
Accurate estimation of human exposures to volatile organic compounds (VOCs) is a key element of strategies designed to protect public health from the adverse effects of hazardous air pollutants. The focus here is on examining the capability of three different exposure metrics (outdoor community concentrations, indoor residential concentrations, and a simple time-weighted model) to estimate observed personal exposures to 14 VOCs. The analysis is based on 2-day average concentrations of individual VOCs measured concurrently in outdoor (O) air in three urban neighborhoods, indoor (I) air in participant's residences, and personal (P) air near the breathing zone of 71 healthy, nonsmoking adults. A median of four matched P-I-O samples was collected for each study participant in Minneapolis/St. Paul over three seasons (spring, summer, and fall) in 1999 using charcoal-based passive air samplers (3M model 3500 organic vapor monitors). Results show a clear pattern for the 14 VOCs, with P > I > O concentrations. Intra-individual variability typically spanned at least an order of magnitude, and inter-individual variability spanned 2 or more orders of magnitude for each of the 14 VOCs. Although both O and I concentrations generally underestimated personal exposures, I concentrations provided a substantially better estimate of measured P concentrations. Mean squared error (MSE) as well as correlation measures were used to assess estimator performance at the subject-specific level, and hierarchical, mixed effects models were used to estimate the bias and variance components of MSE by tertile of personal exposure. Bias and variance both tended to increase in the upper third of the P exposure distribution for O versus P and I versus P. A simple time-weighted model incorporating measured concentrations in both outdoor community air and indoor residential air provided no improvement over I concentration alone for the estimation of P exposure.
Keywords
Airborne-particles; Air-contamination; Air-monitoring; Biohazards; Biological-effects; Breathing-atmospheres; Breathing-zone; Chemical-deposition; Chemical-properties; Chemical-reactions; Demographic-characteristics; Exposure-assessment; Exposure-levels; Exposure-methods; Health-hazards; Indoor-air-pollution; Indoor-environmental-quality; Inhalation-studies; Mathematical-models; Organic-chemicals; Outdoors; Particle-aerodynamics; Physiological-effects; Pollutants; Public-health; Quantitative-analysis; Risk-analysis; Risk-factors; Seasonal-factors; Statistical-analysis; Time-weighted-average-exposure
Contact
Ken Sexton, School of Public Health, University of Texas, Brownsville Regional Campus, RAHC Building, 80 Fort Brown, Brownsville, Texas 78520
CODEN
ESTHAG
Publication Date
20040501
Document Type
Journal Article
Email Address
ksexton@utb.edu
Funding Type
Grant
Fiscal Year
2004
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-T42-OH-008434
Issue of Publication
9
ISSN
0013-936X
Source Name
Environmental Science and Technology
State
MN; TX
Performing Organization
University of Minnesota Twin Cities
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