3M Centre for Respiratory Protection
As a safety manager, you need to ensure you’re using the right respiratory protection measures and equipment. To do that, you’ll first need to know the types and levels of airborne contaminants in your job site. A thorough and well-documented exposure assessment process will help you:
In this step, gather information about your workplace: information about the chemical and biological agents present, the workers and their assigned roles or tasks, and the controls you already have in place to ensure respiratory safety.
Start by collecting as much data as you can. The Safety Data Sheets provided by the manufacturers are a good source for answering many of the following questions, but you may have to dig deeper as well.
It’s not usually practical to measure every worker’s exposure, so you can assess your workforce by determining similar exposure groups (SEGs). If a group of employees perform similar tasks at the same frequency, using similar materials and methods, they can be considered an SEG. You only need to measure exposure for one of each group.
SEGs can be grouped by:
If you have past exposure monitoring data, it can help you determine SEGs, too.
How is your workforce organised? List tasks, who’s assigned to them, how your staff is organised (by team, department, etc.), and the number of people assigned to each task or group.
Once you’ve gathered data on workers or SEGs, each person or group’s potential exposure should be ranked. This will help prioritise the most serious risks so you can monitor them first.
Prioritisation should be based on two measurements:
1. Workers’ or SEGs’ potential for exposure to each chemical present in the workplace. Rank from 1 to 4, with 1 meaning typical exposure is expected to be less than 10% of the exposure limit for that agent, and 4 meaning typical exposure is expected to be greater than the exposure limit. You can base your determination on:
2. The health effects of overexposure to the contaminant. Using the toxicity data gathered during basic characterisation, rank health effects from 1 to 4, with 1 meaning minimal adverse health effects and 4 meaning life-threatening or disabling.
Monitoring enables you to identify any unacceptable exposures. There are three reasons for exposure monitoring:
How many samples to take depends on your objective. Professional judgment should be used in all cases, plus:
Personal monitoring is when samples are collected by attaching a monitor directly to the worker. How long you need to monitor to collect each sample depends on the chemical’s occupational exposure limit and what you’re trying to achieve. For example, you could take:
Certain airborne substances can be collected on-site and analysed by certain laboratories, or in some cases with direct reading instruments. In most cases, the contaminant must be identified in advance, so you can use the appropriate monitoring equipment and procedures.
For information on 3M monitors and recommended laboratories, please contact your local 3M representative.
The criteria for evaluating exposure assessment results should be determined by a safety/health professional prior to exposure monitoring. Once you collect all the necessary data, it must be evaluated to determine whether the exposures are acceptable or not:
Each time you conduct an exposure assessment, make sure there are detailed records of it, including:
Like all parts of your respiratory safety program, exposure assessment is an ongoing responsibility. Even when exposure levels are acceptable, you’ll need to re-evaluate periodically and anytime a new procedure, chemical or workplace change is introduced.
If you don’t have trained safety professionals on staff, you’ll need to hire an outside consultant to conduct your assessment. Even if you have trained professionals, you may want to bring someone in. A consultant may be able to handle the entire process for you or just the parts you need help with.
You can hire an independent outside consultant, or bring in a loss control representative of your workers compensation carrier. Federal and state occupational safety and health departments or local universities sometimes offer consulting programs, too.
The New Zealand Occupational Hygiene Society (NZOHS) website can help you locate an independent consultant.