Qualitative Health Risk and Exposure Assessment
Identifying potential health and regulatory risks is a key element of an effective workplace health and safety program. Where workers perform tasks involving chemicals, including solids, liquids, or gases, it’s important to identify the specific airborne chemicals they may be exposed to. This typically starts with reviewing the product Safety Data Sheet (SDS) to determine chemical(s) in the product(s).
Qualitatively evaluating the exposure risk is the next step and should be conducted by an experienced industrial hygienist to determine which tasks have potentially significant health and airborne exposure risks. Once these significant risks are identified, initial airborne chemical exposure monitoring (i.e., air sampling) should be done to quantify the exposure risk.
OSHA Substance-Specific Standard Check
Where the SDS review identifies a chemical having an OSHA substance-specific standard, that will likely require initial exposure monitoring even if the exposure risk is low, to comply with the OSHA substance-specific standard requirements.
There are 19 OSHA substance-specific standards which are detailed regulations in 29 CFR 1910 Subpart Z. These standards address the unique and severe chronic health risks posed by certain high-hazard materials such as cancer (carcinogens), reproductive toxicity, or specialized neurotoxicity that are not sufficiently covered by general safety guidelines. This includes setting strict permissible exposure limits (PELs) and control measures for each hazardous substance specified in the OSHA substance-specific standards, distinct from the broader Air Contaminants standard (1910.1000).
Results of the initial exposure monitoring determine if additional steps need to be taken to comply with the remaining standard requirements. If the Action Level (AL) is exceeded, then additional requirements apply. OSHA established ALs for substances to trigger proactive safety measures, like increased exposure monitoring and medical checks, before workers exceed the legally enforceable PEL. For most substances, the AL is set at one-half (50%) of the PEL. This buffer helps ensure that even with normal daily fluctuations in exposure, most workers will remain safely below the PEL. Exceeding the PEL requires periodic monitoring, medical surveillance, signage, regulated areas, engineering and work practice controls, respiratory protection, employee training and other requirements depending on the standard.
OSHA Substance-Specific Standards
Regulatory Compliance Versus Health Risk
Interpreting the results of exposure monitoring is an important step when determining regulatory compliance and worker health risk. As mentioned above regarding OSHA substance-specific standards, the air monitoring results would be compared to the OSHA AL and PEL which are legally enforceable limits, to determine regulatory compliance and identify specific actions needed to comply with the standard.
In alignment with industry best practice, industrial hygienists interpret exposure monitoring results by comparing them to the most current Threshold Limit Values (TLVs), which are established by the American Conference of Governmental Industrial Hygienists (ACGIH), unless the OSHA PEL is more stringent. The vast majority of OSHA’s PELs have remained largely unchanged since they were first established in the early 1970s, based on 1968 scientific standards, with only a handful updated since due to legal challenges and complex rulemaking processes prompting OSHA to recommend employers use more protective voluntary guidelines, such as ACGIH TLVs. While legally enforceable, compliance with an outdated PEL doesn’t guarantee safety. OSHA can use its « General Duty Clause » to enforce safer, recommended limits.
TRC Can Help
By understanding your operations, workforce dynamics, budget and priorities, our experienced industrial hygienists can assess exposure risks and develop health and safety programs to meet your specific needs. Our experts also have extensive regulatory expertise and industry-specific qualifications, enabling them to deliver comprehensive, well-informed results. Backed by a deep bench of occupational health and safety expertise, TRC offers end-to-end solutions to support implementation of control measures such as health and safety program development, process engineering, pollution control and more.
Frequently Asked Questions
The results of initial exposure monitoring typically determine how frequent additional monitoring is needed. Where applicable, the OSHA substance-specific standard establishes the regulatory required frequency. In general, results that indicate worker exposures are well-controlled require less frequent periodic monitoring. More frequent monitoring should be performed if the initial results are elevated, especially if they exceed the applicable occupational exposure limit (OEL). Following the addition of exposure controls, such as local exhaust ventilation (LEV), follow-up monitoring should be done to verify adequate exposure reduction has been achieved. Periodic sampling should be done to ensure those controls remain effective and worker exposure risk is well below the corresponding OEL.
If the results of a qualitative exposure assessment performed by an experienced industrial hygienist indicate that there are one or more activities with elevated exposure risk, then airborne chemical exposure monitoring is needed.
