Impact of occupational exposures on exacerbation of asthma: a population-based asthma cohort study.
BACKGROUND
Asthma is a prevalent chronic disease and occupation contributes to approximately 15 % of cases among adults. However, there are still few studies on risk factors for work-exacerbated asthma. The current study investigated the association between asthma exacerbations and occupational exposures.


METHODS
The study comprised all currently working adults (n = 1356) who reported ever asthma in prior population-based cohorts. All subjects completed a questionnaire about exposures, occupations and exacerbations of asthma. Exposure to high and low molecular weight agents, irritating agents and asthmagens were classified using the asthma-specific job exposure matrix for northern Europe (N-JEM). Severe exacerbation of asthma was defined as sought emergency care at a hospital, admitted to a hospital overnight, or made an urgent visit to a primary care physician or district medical office due to breathing problems during the last 12 months. Moderate exacerbation was defined as both being not severe exacerbation and an additional visit to a primary care physician or district medical office, or had extra treatments with corticosteroid tablets. Mild exacerbation was defined as being neither severe nor moderate exacerbation, and increasing usage of inhaled corticosteroids. Multiple logistic regression was applied to investigate the association between exacerbation of asthma and occupational exposures while adjusting for potential confounders.


RESULTS
Approximately 26 % of the working asthmatics reported exacerbation, and more than two-thirds of them had moderate or severe exacerbation. From 23 to 49 % of the asthmatics reported occupational exposure to a variety of different types of agents. Exposure to any gas, smoke or dust (OR 1.7[95 % CI 1.2-2.6]) was associated with severe exacerbation of asthma, as were organic dust (OR 1.7[1.2-2.5]), dampness and mold (OR 1.8[1.2-2.7]), cold conditions (OR 1.7[1.1-2.7]), and a physically strenuous job (OR 1.6[1.03-2.3]). Asthmagens and low molecular weight agents classified by the N-JEM were associated with mild exacerbation, with OR 1.6[1.1-2.5] and OR 2.2[1.1-4.4], respectively.


CONCLUSIONS
Self-reported exposure to any gas, smoke or dust, organic dust, dampness and mold, cold conditions and physically strenuous work, and jobs handling low molecular weight agents were associated with exacerbation of asthma. Reduction of these occupational exposures may help to reduce exacerbation of asthma.
['Kim|Jeong-Lim|JL|', 'Henneberger|Paul K|PK|', 'Lohman|Susanna|S|', 'Olin|Anna-Carin|AC|', 'Dahlman-Höglund|Anna|A|', 'Andersson|Eva|E|', 'Torén|Kjell|K|', 'Holm|Mathias|M|']
D000280:Administration, Inhalation D000284:Administration, Oral D000305:Adrenal Cortex Hormones D000328:Adult D000368:Aged D001249:Asthma D015331:Cohort Studies D018450:Disease Progression D004391:Dust D005260:Female D005658:Fungi D006801:Humans D016015:Logistic Models D008297:Male D008875:Middle Aged D016273:Occupational Exposure D012307:Risk Factors D057566:Self Report D013548:Sweden D017132:Workplace
Occupational exposure Exacerbation Asthma Job exposure matrix Work exacerbated asthma Workplace