Grant: Operating Grant

Asthma has major health consequences and economic consequences the world over. The airways of people with asthma are inflamed and react to irritants by narrowing and making it more difficult to breathe. This typically results in an "asthma exacerbation" whereby the asthmatic experiences shortness of breath, at minimum, and may need urgent medical attention. Diesel exhaust (DE) is associated with asthma exacerbations, but how and why this occurs is unclear. One proposition is that DE causes "oxidative stress", which is damage to cells and body tissues due to certain chemical characteristics of DE particles. Recently, we have shown that oxidative stress is responsible for airway narrowing in asthmatics. We now want to know if this is made worse by the addition of a common allergen (such as that from grass or the birch tree). In our lab, we create DE and finely control its concentration while volunteers inhale it for 2 hours. The concentration of DE is typical of that in a mining operation or on the streets of several developing cites in Asia. Such a short exposure time has no permanent effects but can reveal mild changes in the airways and blood (these return completely back to normal within hours) to help us decide if our hypothesis is correct. Each volunteer subject is exposed, on different days, to DE and to clean air. We after the DE (or clean air) exposure, we add allergen (grass or birch) to the lung, to see if that worsens the effect of DE, and to create the "real world" situation (where multiple asthma triggers are present at one time). This research will allow a better understanding of DE-related airways disease, help workers' advocates and compensation boards better understand the harms of occupational exposure to diesel exhaust, and inform evolving measures to protect all Canadians exposed to traffic-related pollution (such as recommendations regarding exhaust filters or fuel composition, or personal anti-oxidant supplements).