Respiratory Hazards: Verify Workers’ Exposures with Sampling, Analytical Analysis or Objective Data

By: Ray Chisti, Contributor

Did you know employers need to verify their workers’ exposure levels to respiratory hazards? Employers often forget to do this! Federal and state OSHA agencies have continued issuing citations to employers during 2023, because the employers didn’t reasonably estimate their workers’ respiratory exposures.

Once you’ve estimated the exposure, you must select one of three methods to verify your workers’ exposure. These are sampling, mathematical computation or using objective data. If you don’t verify estimated exposures, you may not be compliant with OSHA’s Respiratory Protection Standard. OSHA will continue assessing its standards for more restrictive compliance requirements to protect America’s workforce.

For example, on June 28, 2022, OSHA published an Advanced Notice of Proposed Rulemaking (ANPRM) in the Federal Register concerning medical removal protection and surveillance triggers under its current General Industry and Construction standards. OSHA wants to tackle issues such as blood lead triggers, medical surveillance, permissible exposure limit, PPE, housekeeping, hygiene and training. Affected employers will need to continue ensuring they’re validating respiratory lead exposure estimates. The agency’s efforts on this issue have continued into 2023.

A reasonable estimate isn’t an educated guess, either. Look at the details of the work activity, chemicals used, application method, ventilation, containments and other variables that would affect your workers’ respiratory exposure. This article guides employers on verifying their workers’ estimated exposure levels to respiratory hazards.

If OSHA inspects your workplace, compliance officers generally ask how your workers’ respiratory estimate was performed and how it was verified. (photo courtesy Adobe Stock Images)

Guidance from OSHA

OSHA 1910.134, Respiratory Protection, requires employers to estimate their workers’ exposure to respiratory hazards reasonably. But it also states, “[w]here the employer cannot identify or reasonably estimate the employee exposure, the employer shall consider the atmosphere to be [immediately dangerous to life and health (IDLH)].”

If you must treat the workspace as IDLH, workers must wear respiratory devices with a higher assigned protection factor (APF). This may lead to extra expense in unnecessary equipment, and increased stress and discomfort on workers, because they must wear additional PPE.

If OSHA inspects your workplace, compliance officers generally ask how your workers’ respiratory estimate was performed and how it was verified. If an employer cannot provide this information, it may result in the employer receiving a citation and penalties.

For example, on March 6, 2023, OSHA cited an employer for failing to have an effective respiratory protection program. Workers became sick after having exposure to toxic metal fumes above OSHA’s permissible exposure limit. This employer is facing $195,988 in proposed penalties. An effective assessment and verification of respiratory exposures could have avoided workers’ overexposure to the toxic fumes.

Verifying Reasonable Estimate of Exposure

Sampling is the easiest way to verify exposure levels. A sampling pump draws air through a cassette that collects air contaminants. The cassette is sent to a laboratory for analytical analysis. The lab then reports the results to the employer, who determines workers’ exposure levels. The cost of the equipment, training someone to use it, lab fees, wearing a pump for 7-8 hours, as well as understanding how and when to change out cassettes, are some hurdles that need to be addressed if using this option.

Employers can also use objective data to verify exposure levels, but it can be challenging. Using objective data requires comparing past work (usually within the past 12 months) with the current scope. The work scopes, workers’ training, supervision, containment, ventilation and other controls must be exact. Unless the work activities and related safety resources were set up to be exact, using objective data may not be an easy option.

The final option is having a qualified person perform math computations to determine workers’ exposure levels. A professional engineer, a safety professional or a certified industrial hygienist could do this. You must provide them with specific information, such as work area dimensions, ventilation information, number of workers, safety and product data sheets for chemicals being used, and application methods. This information isn’t always readily available in the early work planning stages before actual work activity begins.

Engineering Controls

Just behind elimination and substitution controls, engineering controls are the third-most effective way to control hazards. Using PPE is the least effective method to reduce hazards. Three engineering controls are:

  • Ventilation
  • Machine guarding
  • Isolation

Engineering controls reduce employee exposure either by removing or isolating the hazard or isolating the worker from exposure using technology. Examples of specific engineering controls include:

  • Exhaust ventilation, such as dust-collection shrouds exhausted through a high-efficiency particulate air (HEPA) vacuum system.
  • Welding, cutting/burning and heating activities should have local ventilation.
  • Design containment structures for abrasive blasting with full containment to optimize ventilation flow, reducing the airborne contaminant concentration and improving visibility. The containment area must be under negative pressure to minimize contaminants from escaping.

As necessary, you must evaluate the mechanical performance of your system in controlling exposure. Proper ventilation is critical to keeping your workers safe and reducing exposure to airborne contaminants.

Engineering controls, such as ventilation, reduce employee exposure either by removing or isolating the hazard or isolating the worker from exposure using technology. (photo courtesy Adobe Stock Images)


General ventilation uses air movement within the general workspace to displace or dilute contaminants with fresh outside air. General ventilation of the workplace also contributes to the comfort and efficiency of employees, because working under extreme conditions of temperature and humidity may harm employee productivity and health.

Employees use respiratory devices to avoid exposure to airborne hazards in their breathing zone. PPE isn’t necessary when ventilation is sufficient to control airborne hazards within acceptable levels. Design air-exchange systems to prevent dispersing fumes, vapors and particulates into the work area and employees’ breathing zones. Employees would benefit from using local ventilation in a designated hot work area. An exhaust fan pulls fumes into a duct that vents it safely outdoors.

Air Exchanges

A common best practice across industries is to maintain at least five exchanges of air per hour. Many state laws require at least six exchanges. Five or six exchanges isn’t a universal requirement under OSHA. Instead, some OSHA standards require six air exchanges for particular situations, like where you have an indoor flammable storage room. The number of air exchanges per hour your equipment can exchange is easily calculated in four steps.

  • First, find the ventilation rate of your mechanical ventilation. This rate will usually be written in cubic feet per minute (cfm) on the equipment’s label.
  • Second, determine the cubic feet of the workspace of concern.
  • Third, multiply 60 by the ventilation rate of your equipment.
  • Finally, divide your answer from step number three above by the square feet of your workspace.

Your answer will provide you with the number of air exchanges per hour that your mechanical ventilation can handle. The number 60 used in step number three represents 60 minutes. Once you have the number of air exchanges, you’ll know if the source of your mechanical ventilation is sized correctly.

Understanding some of these essential things in this article will provide you a general understanding of how estimating exposure and validating sampling works. You will be more confident when making decisions about protecting your workers or interacting with an industrial hygienist.

About the Author:

Ray Chishti is a dedicated Workplace Safety Editor at J. J. Keller & Associates, Inc. Ray’s extensive expertise spans over 18 years in diverse sectors, including fossil fuel power plants, utilities, retail establishments, warehousing and college campus construction. Holding a Juris Doctor with a concentration in Occupational Safety and Health, Ray is an authorized OSHA trainer for both general industry and construction. He holds first aid, AED and CPR certifications, signifying a steadfast commitment to a comprehensive safety landscape.

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