Exposures of Elderly Volunteers with and without Chronic Obstructive Pulmonary Disease (COPD) to Concentrated Ambient Fine Particulate Pollution

Abstract

The elderly and individuals who have chronic obstructive pulmonary disease (COPD) may be sensitive to particulate matter (PM) air pollution. We evaluated short-term health responses of 13 elderly volunteers with COPD and 6 age-matched healthy adults to controlled exposures of ambient PM pollution in suburban Los Angeles. Using a Harvard particle concentrator and a whole-body chamber, we exposed each person on separate occasions to approximately 200 μg/m³ concentrated ambient particles (CAP) less than 2.5 μm in diameter and to filtered air (FA). Each exposure lasted 2 h with intermittent mild exercise. We found no significant effects of CAP on symptoms, spirometry, or induced sputum. A significant negative effect of CAP on arterial oxygenation (measured by pulse oximetry) immediately postexposure was more pronounced in healthy subjects. Peripheral blood basophils increased after CAP in healthy but not in COPD subjects. In both groups, red cell counts increased slightly 1 day after exposure to FA but not to CAP. Preexposure ectopic heartbeats were infrequent in healthy subjects, but increased modestly during/after CAP exposure relative to FA. Ectopic beats were more frequent in COPD subjects, but decreased modestly during/after CAP relative to FA. Heart-rate variability over multihour intervals was lower after CAP than after FA in healthy elderly subjects but not in COPD subjects. Thus, in this initial small-scale study of older volunteers experimentally exposed to ambient PM, some acute cardiopulmonary responses were consistent with effects reported from epidemiologic studies. Unexpectedly, individuals with COPD appeared less susceptible than healthy elderly individuals. Further investigation of older adults is warranted to understand the pathophysiology and public health significance of these findings.

The authors thank M. Avila (Los Amigos Research and Education Institute) and C. Misra and M. Singh (USC School of Engineering) for their contributions. This project was supported by the Southern California Particle Center and Supersite, under grant R827352-01-0 from the U.S. Environmental Protection Agency (EPA). Additional support was provided by U.S. EPA grants R827999-01-0 and R826708-01-0 and National Institute of Environmental Health Sciences grants 5P30 ES07048-06 and 1P01 ES09581-01. Although the research described in this article has been funded by the U.S. Environmental Protection Agency, it has not been subjected to any U.S. EPA review and therefore does not necessarily reflect the views of the agency, and no official endorsement should be inferred.