History of occupational asthma in Canada

Canada has a long history of excellence and innovation in occupational asthma (OA). This article reviews its most significant achievements. Several Canadian clinical researchers were trained in part at the Brompton Hospital in London, UK, with Professor Jack Pepys, often referred to as the “father of occupational asthma.” They then settled in Canada in the 1970s and extended the British tradition in the study of OA. Important Canadian contributions as regards clinical aspects of diagnosis include:Improvement in the diagnosis by assessment of nonspecific bronchial responsiveness with pharmacological agents and of airway inflammation by examination of induced sputum, with methods developed and validated by the late Freddy Hargreave and colleagues, at McMaster University in Hamilton.Evaluation of several aspects of measurement of peak expiratory flow recordings.Improvement in the methodology of specific inhalation challenges with occupational agents.Furthermore, the outcome of OA was described, including its psycho-socio-economic aspects, and new scales of assessing impairment/disability proposed, then endorsed by international organizations. Prospective epidemiological studies were carried out, particularly in apprentices. The efficacy of surveillance programs was assessed. Many studies were carried out in workers exposed to Western red cedar on the west coast and snow-crab on the east coast. Irritant-induced asthma (nonimmunological OA) and variants of OA were also examined in original Canadian contributions. Canadian researchers have also played a major role as leaders of international conferences, as well as consensus documents and guidelines.