Research Projects

Project at a Glance

Project Status: active

Title: Effects of wood smoke exposure on cardiopulmonary responses in healthy & susceptible humans

Principal Investigator / Author(s): Balmes, John

Contractor: University of California, San Francisco

Contract Number: 04-321


Research Program Area: Health & Exposure

Topic Areas: Health Effects of Air Pollution, Toxic Air Contaminants


Research Summary:

Wood smoke is a major component of air pollution in some areas of California. Epidemiologic data show an association between wood smoke exposure and adverse respiratory health effects, including asthma, as well as an association between particulate and gaseous air pollution and increased cardiovascular morbidity and mortality. However, the biological mechanisms mediating these effects are unknown, as there have been no investigations into biological mechanisms that could explain the cardiopulmonary effects associated with wood smoke exposure in epidemiological studies.

Several plausible mechanisms have been proposed to explain the association of adverse cardiopulmonary outcomes with wood smoke exposure. Reduced heart rate variability (HRV) is a well-known risk factor for cardiovascular morbidity and mortality. Pulmonary and/or systemic inflammation has also been proposed as a plausible mechanism. This project is designed to determine: 1) threshold levels of wood-smoke exposure inducing airway inflammation and HRV responses in humans; 2) the influence of asthma status on wood smoke-induced changes in airway inflammation and HRV; and 3) the biological mechanisms controlling these responses.

The investigation will focus on mediators of airway and systemic inflammation, components of the renin-angiotensin system and coagulability that could plausibly influence HRV and mediate the effects reported in the epidemiologic literature. The study will involve healthy and asthmatic subjects who will undergo 2 hr exposures with intermittent mild exercise to filtered air (control), 150 g m-3 wood smoke, 450 g m-3 wood smoke, and a three serial-day exposure to 150 g m-3 wood smoke. The results of this project will help fill a critical data gap: the biological basis for epidemiologic findings that woodsmoke exposure can induce adverse cardiopulmonary effects. The results will provide critical support for possible future regulatory actions.


 

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