Project title: Response to Diesel Exhaust Inhalation among Healthy Subjects: Symptom, Perception and Physiologic Measures
Completed in: 2006
Diesel engine exhaust is a source of particulate matter smaller than 2.5 microns (PM2.5) in diameter that contributes to air pollution. Epidemiologic studies have found associations between health effects and diesel exhaust (DE) exposures, but the mechanisms of toxicity are still unclear. This study investigates acute health effects from controlled DE inhalation exposure through self-reported symptoms and physiologic measures. It also assesses the impact of subject characteristics such as chemical sensitivity, perception and anxiety level on these measures. Healthy subjects each underwent three randomized exposure sessions consisting of filtered air, 100 or 200 mg/m3 DE PM2.5. Subjects are more likely to report nose symptoms at the 200 level as compared to filtered air, OR=2.8 (CI: 1.4, 5.5). The physiologic measures, blood pressure and heart rate, taken during the exposure or across the exposure day do not show an exposure level dependent effect. Subjects with self-reported chemical sensitivity are significantly (p<.01) more likely to report throat, nose, eye, fatigue, and c hest symptoms, regardless of exposure level. Anxiety scores were not significant and did not seem to play a role in this experimental exposure protocol. The primarily negative results have demonstrated that the experimental exposures are tolerable and have alleviated safety concerns, allowing for more susceptible populations to be studied in the future.