The first article in this series discussed OSHA’s final rule on Occupational Exposure to Respirable Crystalline Silica, which reduces the permissible exposure limit (PEL) for crystalline silica from 250 to 50 micrograms per cubic meter of air (μg/m3), averaged over an eight-hour shift.

The compliance date for the new rule for those in the construction industry was September 23, 2017, so it is time to start embracing new tactics. Now that we understand Table 1, let’s go through the available methods for controlling exposure.

Some methods are better than others. OSHA follows this hierarchy of controls:

  1. >Elimination/substitution
  2. Engineering controls
  3. Administrative and work practice controls
  4. Personal protective equipment

The First Line of Defense

Your first line of defense against respiratory hazards on the job-site is elimination or substitution. For this tactic, you phase out the contaminant or substitute a non-hazardous material for the contaminant causing the concern. However, this is not always possible, depending on the project.

If you cannot eliminate or substitute the material, the next best tactic is to employ engineering controls. Engineering controls include the use of a fume hood or ventilation to isolate or dilute the contaminant.

Administrative and work practice controls can also work to reduce individual exposure levels on the job-site. For example, rotate multiple workers through a job-site where contaminants are present. While it makes sense to position someone as a master of a specific task, exposing one worker continuously to respiratory hazards greatly increases his or her risk. Operate on a rotating schedule to give workers a break.


Personal protective equipment (PPE), like a respirator, is not your first line of defense. Instead, PPE should become an option only after the preceding controls have failed to reduce respiratory hazards to below 50 μg/m3. PPE can also be added to your methods as an additional form of protection or used temporarily while other control methods are being put into place. When resorting to PPE, use a National Institute for Occupational Safety and Health (NIOSH)-certified respiratory system.

Choosing a Respirator

There are several types of respirators to choose from. However, the working environment will play a large part in your decision. Having a thorough understanding of both the application and contaminants present is critical to the respiratory protection selection process.

The most commonly used form of respirator is referred to as an air-purifying respirator or APR. APRs use activated carbon and/or mechanical filters to remove hazardous particles from the air as workers breathe. Although these are popular, APRs should not be used in areas where workers are exposed to unknown contaminants or unknown concentrations of contaminants.

Another style of respirator is known as supplied air respirators or SARs. Rather than filtering the air, this category supplies clean, breathable air to a worker from another source. This makes SARs a better choice for situations where the workers could encounter oxygen deficiencies. SARs are also better choices during abrasive blasting. OSHA requires the use of SARs during abrasive blasting because the blasts can negate the effectiveness of APRs.

Filtering facepiece respirators, or “dust masks,” present another option. Check these disposable masks for a National Institute for Occupational Safety and Health (NIOSH) stamp of approval. Approved masks will always have a stamp; if a mask is missing a stamp, it has not been approved. When worn incorrectly, basic dust masks are ineffective. Users often make two critical mistakes. First, users mistakenly employ one band instead of two. Without two bands securing the mask, the mask is improperly sealed. Second, the relationship between facial hair and respiratory system is like that of oil and water: They don’t mix. Facial hair causes small gaps in the seal of the mask, effectively allowing unintended air – and contaminants – entry.

The Right Fit

Finding the right fit doesn’t always refer to the mask; it begins with finding the right person to do the job. Although controls and respirators filter harmful particulate matter from the air, they can also reduce oxygen intake. So, workers with high blood pressure or heart disease may be better suited to other tasks, as would claustrophobic workers, who may feel uncomfortable because of the restrictive feel of the respirator.

You may want to go so far as to include baseline lung capacity testing in your risk management program. Medical professionals should test new hires’ air volume and speed using a spirometer. Annually, workers should get retested for any changes in their results. X-rays also detect evidence of silicosis specifically.

In addition to selecting and fitting necessary equipment and respirators to employees, your program should include:

  1. Routine training on proper use
  2. Training on respiratory hazards
  3. Training on emergency respirator use
  4. Schedules for cleaning, disinfecting, storing, inspecting, repairing, discarding, and maintaining respirators
  5. Updates to a written program to account for changes in the workplace affecting respirator use

Talk with workers about the respiratory risks of working around substances that contain silica, and talk with them about your risk management strategy. This way, whether particulate matter kicks up in a sawdust storm or floats invisibly, workers will know the risks.


  1. “Do You Have Questions About Disposable Dust Masks? We Have Answers!” EHS Today. October 12, 2017.
  2. “Respiratory Protection Selection Made Easy (Or At Least, Less Confusing)” EHS Today. October 12, 2017.
  3. OHSA’s New Silica Rule – Overview and Resources” Builders Mutual. 2017.
  4. “Silica in Construction Toolkit” National Association of Home Builders. 2017.
  5. “OSHA Crystalline Silica Rule: Construction” OSHA. 2017.