Abstract 11545: Wood Smoke Inhalation Does Not Impair Vascular Function or Increase Thrombogenicity in Healthy Firefighters

Abstract

Background Myocardial infarction is the leading cause of death in on-duty firefighters and has been linked to fire suppression duties, although underlying mechanisms are unclear. During fire suppression, firefighters are exposed to excess air pollution whilst extinguishing wildland fires, often without respiratory protection. We investigate the effect of wood smoke inhalation on vascular endothelial function and thrombogenicity in firefighters. Methods In a double-blind randomized cross-over study, 16 healthy male firefighters were exposed to wood smoke (∼1 mg/m3 particulate [PM10] concentration) or filtered air for 1 hour during intermittent exercise. Bilateral forearm blood flow was measured before and during unilateral intrabrachial infusion of bradykinin (100 - 1000 pmol/min), acetylcholine (5 - 20 µg/min), sodium nitroprusside (2 - 8 µg/min), and verapamil (10 - 100 µg/min) 4 - 6 hours after exposure. Thrombus formation was measured using the Badimon chamber 2 hrs post-exposure and platelet activation measured at 0, 2 and 24 hrs post-exposure. Results There was a dose-dependent increase in forearm blood flow with each vasodilator (P<0.01 for all), however there were no differences in response to acetylcholine (P=0.91), sodium nitroprusside (P=0.52) or verapamil (P=0.63) between exposures. Bradykinin caused a dose-dependent release of tissue plasminogen activator (P<0.01) which was similar after both exposures (P=0.72). Thrombus formation was unchanged under low or high shear conditions (P=0.96 and P=0.55 respectively), and there were no differences between platelet-monocyte aggregates at 2 and 24 hrs (P=0.90 and P=0.65 respectively) following either exposure. Conclusions Wood smoke inhalation does not impair vasomotor or fibrinolytic function nor increase thrombus formation or platelet activation in healthy firefighters. Cardiovascular events during fire suppression may not be directly related to wood smoke inhalation but precipitated by other mechanisms such as strenuous physical exertion or dehydration.