Respiratory Protection Basics

Your lungs have no way to warn you about most airborne hazards. Silica, welding fume, isocyanates and solvents can do damage long before you feel anything, and an atmosphere without enough oxygen can drop you in seconds. A respirator can protect you, but only if it is the right type, it seals to your face, and it is cared for. It comes after the employer has tried to control the air by other means, such as ventilation, wet methods or a safer product.

What You Will Be Able to Do

• Say when a respirator is required and what must happen before you wear one.
• Tell filters from cartridges and match them to the hazard.
• Use assigned protection factors to see whether a respirator is good enough.
• Do a user seal check.
• Say when an air-purifying respirator will not protect you at all.

When a Respirator Is Required

OSHA's rule, 29 CFR 1910.134, applies in general industry and, through 1926.103, in construction. Employers must first use feasible engineering controls. A respirator is required when those controls cannot bring exposure below the Permissible Exposure Limit (PEL), the legal limit for an airborne substance, or while the controls are being put in place.

Whenever respirators are required, the employer must run a written program with a program administrator, and provide these at no cost to you:

1. Medical evaluation. A respirator makes breathing harder, so you must be cleared before you are fit tested or use one.
2. Fit test. A test of the exact make, model and size you will wear, before first use and at least once a year. You need a new one if you change models, or if your face changes through weight change, dental work or surgery.
3. Training. At least yearly, covering why the respirator is needed, how to use it and its limits.

Fit tests can be qualitative, using a taste or smell test agent, or quantitative, using a machine that measures leakage.

Warning: A tight-fitting respirator cannot be worn with facial hair where the facepiece seals. Stubble is enough to break the seal. If you must wear one, you must be clean-shaven in the seal area every time.

Voluntary Use

If you wear a respirator when it is not required, your employer must give you the information in Appendix D of the standard and make sure your use does not create a hazard. Workers who only wear disposable filtering facepieces voluntarily do not need a program. Other voluntary respirators, such as a reusable half mask, still need a medical evaluation and proper care.

Types of Respirators

Filter respirators and PAPRs clean the air around you. Supplied-air respirators and SCBAs bring in clean air from somewhere else. That difference decides where each can be used.

A dust mask that lacks NIOSH approval is not a respirator. Look for the NIOSH label and approval number on anything you rely on.

What the APF Tells You

An assigned protection factor is how many times the outside concentration a properly used respirator can handle.

Worked example: The PEL for respirable crystalline silica is 50 micrograms per cubic meter of air. Air sampling shows 300.

1. Maximum for a half mask: 10 x 50 = 500. 300 is under 500, so APF 10 works.
2. If sampling showed 800, a half mask would not be good enough. A full facepiece at APF 50 would allow up to 2,500.

Filters and Cartridges

Choose by contaminant, concentration and oxygen level. Particles need a filter. Gases and vapors need a chemical cartridge. A particle filter does nothing against solvent vapor, and a vapor cartridge alone will not stop dust.

Particle filters carry a letter and a number. N means not oil resistant, R means oil resistant, and P means oil proof. The number is the efficiency: 95, 99 or 100, with 100 meaning 99.97%.

Gas and vapor cartridges are specific, and the standard color codes help. Always read the label.

When Cartridges Run Out

A particle filter gets harder to breathe through as it loads up, so replace it when breathing gets difficult or the filter is damaged or dirty.

Chemical cartridges wear out without warning. OSHA requires a NIOSH-approved end-of-service-life indicator, or a written change schedule based on data, such as how much of the chemical is in the air and how long you are exposed. Do not use smell as your plan. Many chemicals have no smell at dangerous levels, and some deaden your sense of smell. If you do smell or taste something through the respirator, leave the area at once, then check the seal and the cartridge.

Doing a User Seal Check

You must do this every time you put on a tight-fitting respirator. It does not replace the fit test.

1. Put the respirator on and tighten the straps as you were trained.
2. Positive pressure check: Cover the exhalation valve and breathe out gently. The facepiece should bulge a little and hold pressure.
3. Negative pressure check: Cover the cartridges or filter and breathe in gently. The facepiece should pull in a little and stay there for about 10 seconds.
4. If you feel a leak, adjust and try again. If you cannot get a seal, do not enter the area.

Follow the maker's seal check if it differs, particularly for disposable facepieces.

When Filtering Is Not Enough

Filter respirators do not supply oxygen. Never use one where oxygen is below 19.5%, in an unknown atmosphere, or in an atmosphere that is immediately dangerous to life or health (IDLH). IDLH means a level that could kill you, cause lasting harm, or stop you from escaping.

For IDLH conditions, OSHA requires a full-facepiece pressure-demand SCBA rated for at least 30 minutes, or a pressure-demand supplied-air respirator with a backup air supply. If your employer cannot identify or reasonably estimate the exposure, the atmosphere must be treated as IDLH.

Caring for Your Respirator

1. Inspect it before each use: straps, valves, cracks and the facepiece.
2. Clean reusable facepieces after use with the maker's method.
3. Store it in a sealed bag or container, away from dust, sunlight and chemicals, without bending the facepiece.
4. Replace damaged parts with parts from the same maker. Mixed parts void the NIOSH approval.
5. Throw out disposable respirators when they are dirty, damaged or hard to breathe through.

Common Mistakes

Check Your Understanding

1. You spray a solvent-based coating in a booth. Your coworker hands you an N95. Is that right?

No. An N95 only filters particles. You need the respirator your program specifies, typically organic vapor cartridges with a particle prefilter, or supplied air.

2. You have been fit tested on a medium half mask from one maker. The shop now stocks a different brand. Can you just swap?

No. A different make, model or size needs a new fit test.

3. You grew a beard over your vacation. Your job requires a half mask. What are your options?

Shave the seal area, or talk to your employer about a loose-fitting PAPR if the hazard allows it. A tight-fitting mask is not allowed.

4. A meter shows 18% oxygen in a pit. A coworker says a full-face cartridge respirator will cover it. Will it?

No. Cartridges do not add oxygen. Do not enter. That atmosphere needs ventilation, or supplied air or SCBA, under your entry procedures.

Key Takeaways

• Respirators come after engineering controls have been used.
• Required use means a written program, a medical evaluation, an annual fit test and training, at no cost to you.
• Match the filter or cartridge to the contaminant, and use the APF to check protection.
• Do a seal check every time, and keep facial hair out of the seal area.
• Change cartridges on a schedule. Never rely on smell.
• Air-purifying respirators do not work in low oxygen or IDLH conditions.