In HazMat, OSHA

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Wildfire ash and smoke consists of fine particles and gases from burning trees and other plants. When wildfires reach buildings and other human-made structures, they can release other harmful chemicals into the air. Those chemicals can irritate your lungs, throat, nose and eyes, causing coughing, wheezing and difficulty breathing. Wildfire smoke inhalation can also cause cancer and exacerbate chronic lung and heart conditions.

Paper, surgical and fabric masks do not provide enough protection to prevent smoke from entering the lungs. To fully protect the lungs from fine smoke particles, people need to wear respirators — masks that filter ash and smoke particles so you don’t breathe them in. These masks fit tightly to the face to cover the mouth and nose to ensure protection. The Occupational Safety and Health Administration (OSHA) requires employees who work in hazardous environments to wear respirators. But the mask needs to fit properly to function properly.

Preparing for a Respirator Fit Test

The first step to preparing for a respirator fit test is to choose a respirator. When you choose a respirator, consider factors like:

  • Your job responsibilities
  • What toxins you will be exposed to
  • How concentrated the toxins are
  • How long you will be exposed to them

Once you choose a respirator, you will need to bring it along to your fit test.

Other items you should bring along to your fit test include any other personal protective equipment (PPE) that could prevent the respirator from sealing tightly against the face. These equipment items could include coveralls, face shields, hearing protection, hard hats and safety glasses. You must also make sure your face is clean-shaven before your fit test because facial hair can also interfere with a respirator’s seal. It’s important that the respirator fits properly even when you are wearing additional equipment.

It's important that the respirator fits properly even when you are wearing additional equipment.

Respirator Medical Evaluation Questionnaire

Before starting a respirator fit test, you must also complete an OSHA Respirator Medical Evaluation Questionnaire. This is a mandatory evaluation for fit tests, and employers are required to provide time for their employees to complete it. The questionnaire asks questions about your medical history and current health condition. You will need to bring your questionnaire along to your fit test, and a physician or health care provider will review it.

The questionnaire will help the health care provider determine if you are medically able to wear a respirator, if you have any medical limitations for wearing it and if you require any follow-up evaluations. The health care provider will use these criteria to provide a written recommendation that clears you to wear a respirator.

Quantitative and Qualitative Respirator Fit Tests

Once you are cleared to use a respirator, you will complete either a quantitative fit test or a qualitative fit test:

  • A quantitative test numerically calculates a respirator’s effectiveness using measurements. This test uses a machine to measure any leakage in your respirator.
  • A qualitative test uses vapor test agents to test a respirator’s effectiveness. During a qualitative test, the respirator user is exposed to vapor test agents. If the user cannot taste the vapor, the respirator is safe and effective, but if the user can taste the vapor the respirator is inadequate or improperly fitted.

Choosing the Best Respirator for Wildfire Smoke

N95 respirator masks are the most effective respirators against wildfire smoke. Basic N95 masks have two straps to secure around the head and are made of lightweight materials. More advanced N95 masks have one-way exhalation valves that allow you to exhale easier without allowing outside air to get in. They also help keep you cool in extreme temperatures, and they are made of lightweight materials. The most effective type of N95 mask includes a pair of replaceable filters.

How Long Does a Respirator Filter Last?

Respirator filters typically last about six months, so they need to be changed about twice a year. Filters need to be replaced when they become dirty or physically damaged. The filter also needs to be replaced if you find it difficult to breathe while wearing the respirator.

The following factors are also important when choosing a respirator for wildfire smoke:


Respirators should be large enough to cover your nose and chin but small enough to create a firm seal that effectively blocks smoke and particles from getting through. The mask should completely cover your mouth and nose so no parts of them are exposed, but it’s also important that there are no gaps between the mask and your face.


Respirators with two straps are more effective than respirators with one strap. This is because two straps will ensure the respirator remains on the face without shifting or moving around. A respirator with only one strap is a risk for moving off the face, while respirators with two straps have one strap above the ear and one below to keep the mask securely in place.


Respirators are most effective when they are made of lightweight materials. Heavy masks can sag down on the face and potentially expose your nose to smoke and particles. Lightweight materials will stay in place easier, feel more comfortable and keep your face cool.

The Importance of Proper Respirator Fitting

Respirator fit tests are crucial because they ensure respirators fit well to provide the most protection from harmful pathogens. During a fit test, trained professionals will determine the best respirator for a person and adjust it so it forms a seal to the face and keeps pathogens out.

It’s also important to have regular fit tests completed annually to ensure the fit is consistent and still offers protection. Fluctuations in weight can affect the way a respirator fits. If a respirator becomes too loose, it can expose you to harmful particles. The longer you wait between respirator fit tests, the higher risk your respirator will not properly protect you.

The National Institute for Occupational Safety and Health (NIOSH) conducted a study to determine the relationship between weight changes and how well respirators fit, as well as the length of time between respirator fits and the percentage of inadequately fitted respirators. From this study, they found that 10% of people needed a fit adjustment after waiting one year for a fit test, but 20% of the people who waited two years for a fit test needed a fit adjustment.

The research also revealed that of the participants who lost more than 20 pounds, 24% needed a respirator fit adjustment. Researchers concluded that respirator users should undergo another fit test if they’ve lost more than 20 pounds since their most recent fit test.

In addition to ensuring the respirator is properly fitted to the user’s face, respirator fittings also give users the opportunity to review the correct methods for using respirators.

Learn More About Respirator Safety With Hazmat School

Learn More About Respirator Safety With Hazmat School

If you or your employees work in hazardous conditions such as wildfires, it’s essential to know how to safely and effectively use a respirator mask. You must remember the importance of completing fit tests regularly, and you must know how to properly wear a respirator so it protects you against the dangers of wildfire smoke.

Hazmat School offers affordable first responder safety courses you can take at your own pace. Experienced remote instructors are available 24 hours a day if you need help, and at the end of each course, you will receive a certification. Contact Hazmat School to learn more about our classes.

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