Measuring individual ozone exposure in Los Angeles urban parks
|Authors:||Pamela E. Padgett, Patricia L. Winter, Lee-Anne Milburn, Weimin Li|
|Type:||General Technical Report (GTR)|
|Station:||Pacific Southwest Research Station|
|Source:||Gen. Tech. Rep. PSW-GTR-274. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 61 p.|
Exposure to ozone pollution has serious health risks. Damage to lungs and impairment of cardiovascular health are of particular concern for vulnerable populations, including children, the elderly, and individuals from “disadvantaged” communities whose health may already be compromised. This report describes three successive studies that led to the development of techniques for directly monitoring human exposure to ozone. Experiment 1 was a proof of concept and exploration of potential systematic errors. Experiment 2 was a more extensive use of personal monitoring to evaluate differences in ozone exposure based on differing urban structure, which contrasted “disadvantaged” and “affluent” communities. These communities varied across multiple environmental (e.g., percentage of canopy cover), social (e.g., percentage of communities of color), and economic (e.g., median household income) criteria. Experiment 3 built on earlier studies with modifications to address the codependency of ozone concentration and geography as well as the high daily variability of ambient ozone concentrations, which requires that comparisons between different locations be conducted on the same day.
Passive sampling techniques were used to monitor human exposure. Typically these devices are used to monitor ambient conditions in remote areas. When deployed for those types of studies, the devices are protected from the direct effects of wind by baffles and shields; thus ambient conditions are calculated by diffusion of ozone across still air rather than uninterrupted impacts of ozone on the detection surface. In these studies, we amended the normal deployment protocols so that the passive samplers were worn by individuals in a way to mimic the direct exposure of the respiratory system to ozone as a result of wind, body movement, and position.
The current regulatory standards for ozone exposure were established to protect human health; however, direct monitoring of individuals is seldom implemented. Our data suggest that humans engaged in outdoor activities are frequently exposed to several times the 8-hour standard of 65 parts per billion set for vulnerable populations.