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ASSESSING ASTHMATIC CHILDREN'S EXPOSURES TO TOXIC AIR POLLUTANTS AND THE POTENTIAL INHALED DOSES USING TIME ACTIVITY INFORMATION AND ENERGY EXPENDITURE DATA
Citation:
Stevens, C, R W. Williams, AND T R. McCurdy. ASSESSING ASTHMATIC CHILDREN'S EXPOSURES TO TOXIC AIR POLLUTANTS AND THE POTENTIAL INHALED DOSES USING TIME ACTIVITY INFORMATION AND ENERGY EXPENDITURE DATA. Presented at International Society of Exposure Analysis 14th Annual Conference, Philadelphia, PA, October 17-21, 2004.
Impact/Purpose:
Develop simple questionnaires and measures for input into models to classify children's exposures to CRPs, PM, and air toxics.
Quantify personal, indoor air, outdoor and ambient site concentrations for CRP/PM/air toxics for the participants in this pilot study.
Identify and model key factors contributing to the inter- and intra-personal variability between personal measures and corresponding indoor, outdoor, and ambient air concentrations for CRP/PM/air toxics.
Evaluate the contribution of ambient sources to indoor air and personal concentration measurements for CRP/PM/air toxics.
Apply the scientific tools developed and information gained from this pilot in the NCS to assess children's exposures.
Description:
Accurately quantifying human exposures and the potential doses of various populations to environmental pollutants is critical for the U.S. Environmental Protection Agency to assess and manage human health risks. The Tampa Asthmatic Children's Study (TACS) was a pilot research study that monitored exposures to combustion related products, PM, and air toxic pollutants. Children's activities were recorded by the parents every fifteen minutes in a time activity diary, and accelerometers (Actical( R) physical activity monitor) were worn by the children to determine exertion levels and energy expenditures. The activity pattern data were collected to categorize the children's activities by their levels of energy exertion for each activity. Energy expenditures associated with these activities were used to estimate the children's ventilation rates and potential pollutant doses.
Digital accelerometer data was determined to be highly correlated (r=0.9) with the time activity diary (TAD) information for the level of activity for each participant. These results indicate that the information entered by the participants' parents in the TAD were validated by the accelerometers. Data analyses determined that the energy expenditure and the estimated ventilation rate generally increased with age, with the child's weight being the determining factor. This asthmatic cohort, on average, had reduced ventilation rates when compared to the expected or predicted ventilation rates of children without asthma. The average reductions were 45% of the recommended rates for similar children without asthma (age and/or weight). These reductions in their predicted ventilation rates were consistent with asthmatic children with severe persistent symptoms of asthma (
Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.