Hesperian Health Guides

Masks and respirators

A mask or respirator can provide some protection from dust, germs, fumes, mists, and chemicals in the air if it fits you well and is the right kind for the dangers of your job and workplace.

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Loose masks only protect you from germs. They do not protect from dust or chemicals. Particulate masks protect you from some dusts. They do not protect you from chemical vapors or very small dust. Respirators with filters protect you from chemicals and dusts only if they use the correct filters for those substances.

If you have asthma or other breathing problems, it might be difficult to breathe using a mask or respirator. If one is required, ask to be moved to a different job. If your boss will not make changes, let your co-workers know you have breathing problems and tell them what they need to do in case you have difficulty breathing. The factory should have doctors examine all workers who use respirators to make sure they are healthy enough to do the work.

Some dusts are more dangerous than others. Cotton dust can cause byssinosis, silica in sandblasting can cause silicosis and lung cancer, and asbestos dust can cause severe lung problems and cancer. Wear a respirator with a HEPA filter (High- Efficiency Particulate Air), labeled N-100, if you work where there is very fine or small dust. A HEPA filter can filter almost 100% of the particulates and is the best for small particulates. The finest dusts are the least visible — and the most dangerous.

When you wear a mask or respirator because there is enough dust or chemicals in the air to harm you, also wear gloves, eye protection, and protective clothing to protect your skin and eyes.

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Make sure your mask covers both your nose and mouth.

Loose cloth or paper masks

Loose-fitting masks offer very little protection from dust and do not protect from chemical vapors. Since they do not seal around your face and mouth, they let dust in. Chemical vapors pass right through the paper or cloth. Only masks with filters will protect you from breathing in chemicals.

Make a cloth mask for dust

Instead of covering your face with a cloth that lets dust in through the bottom…
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...make a mask that fits more closely over your nose and mouth.
  1. Cut 2 strips of cotton fabric about 10 to 12 cm wide and long enough that you can tie them around your head comfortably. Stitch the edges, or at least take all the threads off the ends.
  2. Place the center of one of the strips on top of your nose. Tie the ends behind your head.
  3. Then put the center of the other strip over your mouth and tie the ends behind your head. Make sure the edge of the cloth on top of your nose is underneath the seam of the one covering the mouth.
    You can make a more permanent mask by sewing the pieces together. Or make many! Wash the mask by itself, not with other clothes.

Dust mask

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Tight-fitting paper or plastic masks, also called "particulate masks," catch dust and germs but they do not protect you from breathing many chemical vapors or very fine dust.

Different kinds of particulate masks are categorized with numbers and letters. The higher the number, the more particulates the mask will filter. Standard particulate masks often look the same so find out their number and what they are good for. These often clog quickly and cannot be used more than one day.

a dust mask with a label that reads "N95."
The "95" means that this mask filters out 95% of particles.
Check the mask and its box or bag to make sure the mask is the right kind for the substance you are working with.

a 2-filter respirator covering part of a worker's face.
Cartridge filters
Respirators can have 2 filters on the sides or one in the center, and can cover parts or all of your face.

Respirators with filters

Also called rubber masks or masks with filters, respirators have filters that prevent some of the chemicals or dusts in the air from getting into your lungs.

Respirators protect you when:

  • they fit you well.
  • they have the right filters for the chemicals you and others are using in your workplace.
  • the filters are replaced when necessary.

Respirators can cover the nose and mouth or the entire face. If they are too large or too small and do not make a seal against your skin, you will be breathing air that is not filtered, which can harm you.

The filters stop certain chemicals and substances from passing into your lungs. After a certain amount of time (see the box or instructions), filters are used up and no longer work. Your factory should have a system for cleaning and changing the filters regularly, before they stop protecting you. Changing filters also makes it easier to breathe using the respirator. Read the box to know how long the filter should be used and to be sure it is the right one to use in your brand of respirator.

Countries have different laws regarding the use of respirators. Look at the label and Safety Data Sheets (SDS) of the chemical and seek support from health officials, unions or other organizations to get this information. Also find more information in Appendix B: Common chemicals and materials.

a worker wearing a full-face mask with a hose attached to an air tank worn on the back.
Respirators with supplied air need careful cleaning after every use.

Respirators with their own air supply

These masks have tanks of air so the person does not breathe outside air at all. These respirators fit more loosely, but they cover the entire head. Respirators with their own air supply are used when there is no other way to reduce the exposure, such as a chemical spill or accident. They might be necessary for maintenance workers opening or entering machines, or when the chemicals in the air are likely to harm you. They can be heavy and make work more tiring.

Check that your respirator fits and works

Look at it. Move and touch all the parts to make sure they are put together correctly and there are no holes, cracks, or damage.

Try it on. Make sure it fits. Turn your head from side to side and up and down. Check that it does not bump against your shoulder or chest. Speak for 30 seconds to see if moving your jaw and lips changes the fit. Facial hair (mustaches, sideburns, or beards) might not fit in the mask or might not let the mask seal around your nose and mouth. If you will wear goggles or other eye wear, they must fit well when you wear your respirator.

Breathe normally first and then take a deep breath. Can you smell or taste the chemical you are working with? If you can, then it is not working properly. However, some chemicals do not have a smell or you might not be able to smell them. Try to test your mask around chemicals you can normally smell.

Check the seal. Test the respirator every time you put it on. Even if the respirator fits well one day, it might not the next. Always take the time to test the fit of any respirator you wear.

You can check the seal in 2 ways:

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The first way is to do a "negative" pressure test by trying to pull air into the respirator. If no air from the outside comes in, it means the seal is probably good. To do this test, put the respirator on. Put your palm or a cover on top of all the entry points of air from the outside to close them. Take a breath and hold it for a few seconds. The respirator should tighten around your face, and collapse in a little. If it stays like this during the time you hold your breath it is probably sealing well.

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The second way is to do a "positive" pressure test, where you add air to the respirator. If no air escapes, it means the seal is probably good. Cover the exhale valve and breathe out inside the respirator. If the air stays inside the respirator, it is probably a good seal. Use the positive test only when the exhale valve is small enough that one finger or your palm will cover the valve completely.

Clean it. After using it, remove filters and other parts and clean the respirator with mild soap and water. Rinse well with water and mild soap. Any residue left might irritate your skin later. Let it air dry. If you do not have soap, you can also use a cloth with a very small amount of IPA to clean it. IPA might damage the rubber over time, so do not use IPA often.

Protect it. Put the respirator in a bag and store it where it will not be stepped on, crushed, or get dirty.

Replace filters often. Filters may last for a few minutes or a few days, depending on how much chemical is in the air where they are used. Maintenance and other workers exposed to high amounts of chemicals need to replace the filters more often than workers doing other kinds of work. Replace straps, valves, or anything else that does not work properly.

a worker wearing a dust mask while using a spray can labeled "Sealant."
Wear PPE that keeps chemicals off of and out of your body.

Pay attention to your health. Notice any changes in your health that might be a sign that your respirator is not protecting you.

  • You have difficulty breathing or your breathing problems are worse when you wear the respirator.
  • You smell or taste chemicals while using it.
  • You find dust or chemical residue inside it.
  • You feel effects from chemicals while wearing it.
  • You feel sick during or after work with signs of problems that come from chemicals in your work area.

Let your employer know immediately if your respirator is not working well or if you have signs of exposure to chemicals.

This page was updated:28 Feb 2021