A job-exposure matrix for occupational noise: development and validation.

OBJECTIVE: To develop a job-exposure matrix (JEM) for occupational noise in Sweden and to estimate its validity. METHODS: The JEM, developed by a group of experienced occupational hygienists, contains 321 job families with information regarding occupational noise from 1970 to 2004. The occupational noise information derives from measurements collected from different sources. The time period label has a 5-year scale starting in 1970. The estimated average 8h (TWA) noise level in decibel [dB(A)] for every 5-year period was coded either as <75 dB(A), 75-84 dB(A), or ≥85 dB(A) and the risk of peak level exposure assessed. The validity of the JEM is tested, using Svensson's non-parametric methods based on classification consensus, reached by a second group of occupational hygienists. RESULTS/DISCUSSION: Validation results show ~ 80% agreement and no systematic differences, in classification, between the two different groups of occupational hygienists, classifying the occupational noise exposure. However, classification of peak level exposure did show a systematic difference in relative position. The results will give more power to the JEM that it gives a good general estimate for the occupational noise levels in Sweden for different job families during 1970-2004. We, thus, intend to use it in further studies and also make it available to collaborators.

Joint effects of job strain and road-traffic and occupational noise on myocardial infarction.

OBJECTIVES: The aim of this study was to assess the joint effect of job strain and both road-traffic and occupational noise on myocardial infarction (MI). METHOD: We conducted a population based case-control study on first time MI in Stockholm County during 1992-1994. Participants answered a questionnaire and underwent a physical examination. Residential road-traffic noise exposure was based on residential history combined with information on traffic intensity and distance to nearby roads. Occupational noise exposure was assessed by occupational history combined with a job-exposure matrix derived from measurements. Job strain was based on questions regarding psychological demands and decision latitude. A total of 3050 study participants (1252 cases and 1798 controls) were included in the study. RESULTS: An increased risk of MI was indicated among participants exposed to road-traffic noise [odds ratio (OR) 1.23, 95% confidence interval (95% CI) 1.01-1.51], occupational noise (OR 1.17, 95% CI 0.98-1.41) and job strain (OR 1.39, 95% CI 1.17-1.65). Participants exposed to one, two, or three of these factors showed an increased risk (OR 1.16, 95% CI 0.97-1.40, OR 1.57, 95% CI 1.24-1.98, and OR 2.27, 95% CI 1.41-3.64, respectively). Exposure to two or three of these factors occurred among about 20% of the controls. CONCLUSION: Our results indicate that exposure to a combination of noise exposure and job strain increases the risk of MI substantially. Such exposures affect a considerable part of the population, which has relevance for prioritization of preventative measures.