How many individual chemicals are workers exposed to in your workplace? How many workers are exposed to those chemicals? How do you keep up with who is exposed to what, and when you need to monitor for each chemical? What about seasonal factors affecting exposures and other changes over time?
To simplify data collection and hazard characterization, employers whose workplaces pose complex chemical exposures can create hazard profiles called similar exposure groups (SEGs). All workers in an SEG are expected to experience approximately the same level of risk from work-related chemical exposures. This enables industrial hygienists to design monitoring programs that enhance safety while offering the best possible return on investment.
Why Use SEGs?
If you had to assess each worker’s exposure individually, you could blow your entire annual budget—not to mention, an awful lot of time—on industrial hygiene sampling. When workers are grouped by risk profile, fewer total samples are required to characterize overall risk. Only representative samples are needed.
With fewer total samples needed, it is possible to budget resources to more fully characterize risks; for example, collecting representative samples in the summer and winter will reveal seasonal differences in exposures.
Creating Accurate SEGs
In order for an SEG to provide an accurate risk assessment for a group of workers, it is essential to create accurate SEGs. In order to define groups of workers whose exposure profile is similar enough to be characterized by a representative set of samples, begin with close observation of groups of workers. Workers may be readily categorized by job task or job description, process, craft, exposure to a specific agent, or the control measures available to them. Look for workers who:
- Perform similar types of tasks at a similar frequency.
- Use the same materials or processes to complete tasks.
- Perform their tasks using the same procedures.
- Perform job tasks near the same emission source.
Depending on the agents being monitored, workers may fall into more than one SEG.
Observation will help you to create preliminary SEGs, but sampling data will identify differences among individual workers or from one shift to another. For example, first-shift dock workers may unload more—or less—freight than their third-shift counterparts, which could affect their overall exposure to diesel fumes. Or—according to some research—workers on third shift may face a higher risk of cancer than first-shift workers with the same exposure. Historical sampling data may provide the information that you need, or fresh samples can be collected to confirm the observational groupings.