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Protecting workers is the ultimate goal of industrial hygiene, and different approaches are available. Occupational exposure limits are the gold standard for protecting workers and emergency response personnel from exposure to airborne concentrations of hazardous materials. However, only a fraction of the approximately 85,000 chemicals in commerce today have OELs, many of which are becoming increasingly outdated. For a newly minted biotech, nanotech, or polymeric substance, an authoritative OEL is not an option.

Control banding and occupational exposure banding are well-established tools designed to objectively evaluate chemical hazards and support risk management decisions in the absence of defined OELs. NIOSH has taken the lead on developing occupational exposure banding. Among the several control banding approaches, one of the best known is COSHH Essentials from the United Kingdom’s Health and Safety Executive. This post discusses control banding in general and does not address the specifics of any one tool.

Control banding calculates a control method supported by guidance documents that outline controls shown to protect workers’ health. Occupational exposure banding calculates an exposure limit range to compare to; the user must then determine a method and measure exposures to calculate if workplace conditions are within the range.

Both control banding and occupational exposure banding start with hazard information from the substance’s classification according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), which is readily available from section 2 of the substance’s safety data sheets. Both prioritize the hierarchy of controls and provide a decision-making framework to assess chemical substances and develop exposure control guidance, particularly for chemicals without authoritative OELs.

Unlike control banding, occupational exposure banding does not produce specific risk management and exposure control recommendations. Instead, the outcome of occupational exposure banding is an occupational exposure band, or OEB, which defines the range of air concentrations expected to protect worker health. Once an OEB is determined, a method must be developed and measurements taken and analyzed. These bands can be used as targets to help reduce risk. In the NIOSH approach to occupational exposure banding, chemical substances are grouped into one of five bands ranging from A to E. Band E represents the highest hazard while Band A represents the lowest hazard. For risk mitigation purposes, chemicals in Band E are prime candidates for elimination and substitution.

Further, the OEB banding process uses a three-tier approach. Selection of the most appropriate tier for a specific banding situation depends on the quantity and quality of the available data and the training and expertise of the user (ranging from HSE generalist to experienced IH or toxicologist).

Control banding, in contrast, calculates a control approach based on the GHS hazard statement and reserves air monitoring for verifying whether the control is effective. If the control approach identified matches the controls available to the worker, there is adequate protection. If the control approach identified is less than what is available in the workplace, there is work to be done. For the vast number of employers with limited health and safety budgets, more resources can be directed toward worker protection and controls, such as general ventilation and containment. Sometimes implementing the controls costs less than measuring airborne concentrations.

Health hazards often do not fit into many standard risk matrices. Control banding is an internationally recognized method to not only define risk levels but guide controls. If controls are prohibitively expensive, then measurements can be taken to confirm both the need for controls and their effectiveness. Control banding can protect workers faster with less expertise.

Using a banding strategy adds consistency and objectivity to chemical assessments. Too often, a lower level of control is chosen due to an incomplete hazard analysis, or the analysis is biased by the controls currently available or accepted for a task. Because categories and combinations of controls available for a given exposure scenario are not unlimited, they can be defined, ranked, and applied to a wide range of work sites.

Remember that the point is to protect workers. Both control banding and occupational exposure banding protect workers, just in different ways: control banding is fast and easy, and will define risk levels and controls, while occupational exposure banding is available if measurements must be taken to confirm the effectiveness of controls to protect workers.

Note that these banding approaches are solely based on the toxicity information available for a specific chemical substance, whereas OELs are influenced by additional factors. When banding approaches have been compared against available OELs, research has found that COSHH control banding and the NIOSH tier 1 and 2 banding processes resulted in a band that included the OEL or was more stringent than the OEL.

Resources

National Academies Press: “Review of DOD's Approach to Deriving an Occupational Exposure Level for Trichloroethylene” (2019).

NIOSH: “Control Banding.”

NIOSH: “Occupational Exposure Banding: Overview.”

The Synergist: “Banding Together: Making the Case for Occupational Exposure Bands” (May 2022).

The Synergist: “The ‘Bandits’ Speak: NIOSH Considers Feedback from Users of its Proposed Occupational Exposure Banding Process” (May 2018).