title: Occupational risk factors associated with work-exacerbated asthma in Quebec.
abstract: BACKGROUND
  There is limited information regarding the occupational exposures of subjects with a diagnosis of work-exacerbated asthma (WEA).
  
  
  OBJECTIVE
  To: (1) identify potential specific occupational, chemical, biological and physical agents associated with incident cases of WEA and (2) compare these agents with occupational exposures of occupational asthma (OA) and non-work-related asthma (NWRA) cases.
  
  
  METHODS
  Subjects were workers with work-related asthma (WRA) or NWRA referred between 2005 and 2008 to two Quebec clinics specialised in the field of WRA. Specific inhalation challenges were performed to differentiate OA from WEA. Work exposures were assessed using a detailed occupational questionnaire. Exposures to 41 chemical and biological agents were coded in a semiquantitative way according to a combination of indices for concentration in workplace air, frequency and confidence of exposure by an occupational hygienist expert in occupational exposure coding. This expert was blind to the medical status of WEA, OA or NWRA. Five physical agents were coded on a yes/no scale.
  
  
  RESULTS
  153 subjects were enrolled (53 WEA, 67 OA and 33 NWRA). WEA cases were significantly more exposed to ammonia, engine exhaust fumes, silica, mineral fibres, aerosol propellants and solvents, and significantly less exposed to animal derived dust and enzymes than were OA cases. Exposure to physical conditions did not differ between WEA and OA.
  
  
  CONCLUSIONS
  Exposures associated with WEA differ from those associated with OA in this study. A proportion of subjects with WEA may suffer from low-dose irritant asthma, which remains a hypothesis to be tested.
authors.affiliation: Department of Chest Medicine, Sacré-Coeur Hospital, 5400 Gouin West, Montreal, Quebec H4J 1C5, Canada. catherine.lemiere@umontreal.ca
authors.forename: Catherine
authors.initials: C
authors.lastname: Lemiere
authors.forename: Denis
authors.initials: D
authors.lastname: Bégin
authors.forename: Michel
authors.initials: M
authors.lastname: Camus
authors.forename: Amélie
authors.initials: A
authors.lastname: Forget
authors.forename: Louis-Philippe
authors.initials: LP
authors.lastname: Boulet
authors.forename: Michel
authors.initials: M
authors.lastname: Gérin
mesh_terms: D000328:Adult; D000336:Aerosols / Q000009:adverse effects; D000393:Air Pollutants / Q000009:adverse effects; D000641:Ammonia / Q000009:adverse effects; D000818:Animals; D001249:Asthma / Q000150:complications*; D059366:Asthma, Occupational / Q000209:etiology*; D004391:Dust; D004785:Environmental Pollutants / Q000009:adverse effects*; D004798:Enzymes / Q000009:adverse effects; D005260:Female; D006801:Humans; D007509:Irritants / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000009:adverse effects; D009784:Occupational Diseases / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D052638:Particulate Matter / Q000009:adverse effects; D011792:Quebec; D012307:Risk Factors; D012822:Silicon Dioxide / Q000009:adverse effects; D012997:Solvents / Q000009:adverse effects; D011795:Surveys and Questionnaires; D001335:Vehicle Emissions
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D004391:Dust; D004785:Environmental Pollutants; D004798:Enzymes; D007509:Irritants; D008903:Minerals; D052638:Particulate Matter; D012997:Solvents; D001335:Vehicle Emissions; D012822:Silicon Dioxide; D000641:Ammonia