SweJEM: What is a Job-exposure matrix (JEM)?

Our work environment contains many different types of exposures. A lot of these exposures correlate in the workplace such as noise, vibrations, chemicals, air pollution, physically strenuous work, irregular working hours, psychosocial stress, and working in heat or cold.

The need to classify occupational exposure in epidemiological studies, both regarding current exposure as well as historic occupational exposure, has led to the development of so-called job-exposure matrices. A job-exposure matrix (JEM) is a compilation of specific occupational exposure per occupation and time window. A JEM is a compilation of a specific occupational exposure per occupation and time window. It is usually based on measurement reports from individual workplaces regarding chemical and physical exposure such as noise, vibrations, particles and chemicals or on questionnaire surveys regarding physical workload and psychosocial working conditions. With a JEM, one can assess occupational exposure in a cohort or in register data only with the help of an occupational code or occupational title and knowledge of the time period of the exposure. 

A JEM usually consists of an Excel file that is imported into any statistical program to be merged with the data set that the user has. Interlinking takes place via individuals' occupational code. Pay attention to which occupational coding system your data set is coded in, so that you can merge the data set with the correct version of the JEM. The same occupational code in two different occupational coding systems can describe completely different occupations.  

Example of a layout in a JEM:

Occupational coding
Occupational code SSYK96 Occupation in free text Exp year 1970-74 Exp year 1975-79
3121 Computer assistants 1 1
3122 Computer equipment operators 2 2
3131 Photographers 1 1
3132 Image and sound recording equipment operators 2 2

If individual exposure data is not available, the JEM:s can be used to estimate occupational exposure for each occupation. However, all employees in an occupation gets the same estimate and the variance within the same occupation is not covered. 

More information on JEMs:

Although a valuable method in occupational epidemiology, job-exposure -matrices are no magic fix.
Peters S
Scand J Work Environ Health 2020 May;46(3):231-234

Use of the Finnish Information System on Occupational Exposure (FINJEM) in epidemiologic, surveillance, and other applications.
Kauppinen T, Uuksulainen S, Saalo A, Mäkinen I, Pukkala E
Ann Occup Hyg 2014 Apr;58(3):380-96

Anna Persson