Particulate respirators:

• Filter out dusts, fumes and mists.

• Are usually disposable dust masks or respirators with disposable filters.

• Must be replaced when they become discolored, damaged, or clogged.

• Examples: filtering facepiece or elastomeric

respirator.

Chemical Cartridge/Gas Mask Respirator: Gas

masks are also known as “air-purifying respirators” because they filter or clean chemical

gases out of the air as you breathe. This respirator includes a facepiece or mask, and a cartridge or canister. Straps secure the facepiece

to the head. The cartridge may also have a filter to remove particles. 

Gas masks are effective only if used with the

correct cartridge or filter (these terms are often

used interchangeably) for a particular biological or chemical substance. Selecting the proper filter can be a complicated process. There

are cartridges available that protect against

more than one hazard, but there is no “all-inone” cartridge that protects against all substances. It is important to know what hazards

you will face in order to be certain you are

choosing the right filters/cartridges. 

Chemical Cartridge/Gas Mask respirator:

• Uses replaceable chemical cartridges or canisters to remove the contaminant.

• Are color-coded to help you select the right

one.

• May require more than one cartridge to protect against multiple hazards.

What is a respirator?

A respirator is a device that protects you from

inhaling dangerous substances, such as chemicals and infectious particles. Respirators are

among the most important pieces of protective

equipment for working in hazardous environments. Selecting the right respirator requires

an assessment of all the workplace operations,

processes or environments that may create a

respiratory hazard. The identity of the hazard

and its airborne concentrations need to be

determined before choosing a respirator. This

assessment should be done by experienced

safety personnel or by an industrial hygienist.

There are several different types of respirators,

as described below. 

How do respirators work?

Respirators work by either filtering particles

from the air, chemically cleaning (purifying) the

air, or supplying clean air from an outside

source.

Particulate Respirators: Particulate respirators

are the simplest, least expensive, and least

protective of the respirator types available.

These respirators only protect against particles

(e.g., dust). They do not protect against chemicals, gases, or vapors, and are intended only

for low hazard levels. The commonly known

“N-95” filtering facepiece respirator or “dust

mask” is one type of particulate respirator,

often used in hospitals to protect against infectious agents. Particulate respirators are “airpurifying respirators” because they clean particles out of the air as you breathe. 

BULLETIN

General Respiratory Protection Guidance for

Employers and Workers

The information in this bulletin will provide basic information to workers and

employers who may find themselves using respiratory protection for the first

time. The guidance provides information on what respirators are, how they 

work, and what is needed for a respirator to provide protection. 
Powered Air-Purifying Respirator (PAPR):

Powered air-purifying respirators use a fan to

draw air through the filter to the user. They are

easier to breathe through; however, they need

a fully charged battery to work properly. They

use the same type of filters/cartridges as other

air-purifying respirators. It is important to

know what the hazard is, and how much of it is

in the air, in order to select the proper

filters/cartridges. 

Self-Contained Breathing Apparatus (SCBA) is

the respirator commonly used by firefighters.

These use their own air tank to supply clean

air, so you don't need to worry about filters.

They also protect against higher concentrations of dangerous chemicals. However, they

are very heavy (30 pounds or more), and

require very special training on how to use and

to maintain them. Also, the air tanks typically

last an hour or less depending upon their rating and your breathing rate (how hard you are

breathing). 

Self-Contained Breathing Apparatus:

• Provide clean air from a portable air tank

when the air around you is simply too dangerous to breathe.

All of these respirators (except for the “dust

masks” or filtering face pieces) are available in

either half-mask or full-face pieces.

What are respirators made from?

Filtering facepiece (dust masks) are generally

made directly from a cloth-like filter material.

Chemical cartridge/gas mask respirators can be

made from a variety of materials. The most

popular facepiece materials are silicone, neoprene, and rubber. In general, rubber and neoprene are rigid, durable materials. Silicone is

usually preferred for its comfort, flexibility and

ease in cleaning. Full-face respirators are available with strap harnesses or ratchet suspensions. The harness type can be worn under a

hard hat, but ratchet suspensions are generally

easier to adjust, making donning and doffing

easier. 

What optional features are available 

for respirators?

Various features are available to help you customize respirators to suit your employees and

the specific hazards they encounter. For example, nose cups reduce lens fogging with full

facepiece respirators and lens covers protect

the lens from paint, minor chemical splash and

scratches. 

Spectacle kits are needed when using prescription corrective lenses. The frame mounts into

full-face masks, and the prescription lenses are

made by the users’ optometrist. This allows

the wearer to maintain a proper fit and still

wear prescription lenses. 

How are particulate filters classified?

There are nine classes of particulate filters

which are broken down into three series: N, R,

and P. Each series (N, R, and P) is available at

three efficiency levels: 95%, 99%, and 99.97%.

The N series filter is used in environments free

of oil mists. The R series filters can be exposed

to oil mists, but should only be worn for one

work shift. The P filter can be exposed to oil

mists for longer than one work shift. 

What is the color coding for gas mask

chemical cartridges/canisters?

All cartridges are assigned a color designating

the type of contaminant they filter: 

Contaminant Color Coding on Cartridge/Canister

Acid gases White

Hydrocyanic acid gas White with 1/2 inch green stripe completely around the 

canister near the bottom.

Chlorine gas White with 1/2 inch yellow stripe completely around the 

canister near the bottom.

Organic vapors Black

Ammonia gas Green

Acid gases and ammonia gas Green with 1/2 inch white stripe completely around the 

canister near the bottom.
Carbon monoxide Blue

Acid gases & organic vapors Yellow

Hydrocyanic acid gas and 

chloropicrin vapor Yellow with 1/2 inch blue stripe completely around the 

canister near the bottom.

Acid gases, organic vapors, and 

ammonia gases Brown 

Radioactive materials, except 

tritium & noble gases Purple (magenta)

Pesticides Organic vapor canister plus a particulate filter

Multi-Contaminant and CBRN agent Olive 

Any particulates - P100 Purple

Any particulates - P95, P99, 

R95, R99, R100 Orange

Any particulates free of oil - 

N95, N99, or N100 Teal

Are there any cautions or limitations

when using respirators?

Yes. Each type of respirator can come in several

varieties, each with its own set of cautions, limitations, and restrictions of use. Tight fitting respirators require fit testing to ensure an adequate

fit to the face, and cannot be used with facial

hair. Certain escape respirators use a nose clip

and mouthpiece, which is clenched between

your teeth, similar to a snorkel. Some respirators prevent the user from talking while others

have speaking diaphragms or electronic communication devices. Every respirator contaminated with hazardous chemicals should be

cleaned and decontaminated or disposed of

properly.

All respirators require training in order to be

properly used. Sometimes you can practice

using your own respirator. Some escape respirators come in a package that must remain

sealed until use, so you need to be trained using

a special “practice” version. Training is extremely important in regard to the storage, maintenance, use, and disposal of the respirator. This

information is provided by the supplier of the

respirator (i.e., seller, distributor, or manufacturer).

If you do not use a respirator correctly, it is

very likely that it will not adequately protect

you and may even hurt you. 

How well does a respirator need to fit me?

If your mask does not make a tight seal all the

way around your face when you inhale, you

may breathe contaminated air that leaks around

the edges of the face seal. Most respirators

come in different styles and sizes, and fit different people differently because people's faces

have different shapes. You also need training to

know how to correctly put the mask on and

wear it correctly. This information should be

provided by the supplier of the respirator.

The only way to tell if a tight-fitting respirator

fits you properly, and is capable of protecting

you, is to fit test the respirator. Fit testing can

be accomplished a number of different ways

and should be done by a health and safety professional before workers wear a respirator in a

hazardous environment. Respirators must be

checked for proper fit each time they are donned

to ensure they provide adequate protection.

Can I wear a respirator if I have a beard?

Anything that prevents the face mask from fitting tightly against your face, such as a beard

or long sideburns, may cause leakage. If your

respirator requires a tight fit, you must trim

back your beard so that it will not interfere with

the face-facepiece seal. If your respirator is a

loose-fitting (hooded) positive pressure respirator (e.g., a powered air-purifying respirator,

PAPR) then you may have a beard. 

If I have the right cartridges/filters for a

certain hazard, and my mask fits, will they

always protect me against that hazard?

No. Gas masks and respirators reduce expo-
sure to the hazard, but if the exposure is such

that it goes beyond what the filter is capable of

handling (either because the amount of toxic

gas or particles is more than what the filter is

designed to handle, or because the exposure

lasts longer than what the filter is designed to

handle), the filter may not be effective in providing required protection. Also, there may be

a small amount of leakage even if the fit of the

respirator has been tested. If so, and if there is

a large amount of a toxic chemical in the outside

air, even that small leakage can be dangerous.

Can anyone wear a respirator?

No. Breathing through a respirator is more difficult than breathing in open air. People with

lung diseases, such as asthma or emphysema,

elderly people, and others may have trouble

breathing. People with claustrophobia may not

be able to wear a full facepiece or hooded respirator. People with vision problems may have

trouble seeing while wearing a mask or hood

(there are special masks for people who need

glasses). Employees must be medically evaluated before assigned to use a respirator.

Will my cartridge/filter and respirator

mask protect forever?

No. Cartridges, filters, and masks get old. If

the filter cartridges are outdated, have been

open to the air or are damaged, you may not

be protected. Cartridges that contain charcoal

or other chemicals for filtering the air should

be kept in air-tight packages until use. If cartridges are open or not packed in air-tight packaging, they should not be used. Even cartridges in original packaging have expiration

dates that should be checked before purchase

and use. Also, over time your mask can get

old and break down. Keep your mask in a

clean, dry place, away from extreme heat or

cold. Inspect it before and after use according

to the manufacturer’s instructions. Cartridges

also have a limited service life; they must be

changed periodically during use.

Will a gas mask protect me if there is not

enough oxygen in the air?

No. Air-purifying respirators do not provide

oxygen. If used in an environment with low

oxygen levels, such as in a fire or a confined

space, you are in danger of asphyxiation. 

Will a gas mask protect me if there is 

a fire?

Most will not. It's important to read the manufacturer's information if your main concern is

to be able to escape from a smoke-filled building. Smoke particles can rapidly clog gas mask

filters, and filters with special chemicals are

needed to protect against carbon monoxide

and other gases that may occur in a fire. Not

all gas masks or escape respirators protect

against these hazards. Some components,

including hoods and facepieces, of many of the

gas masks and escape respirators may melt if

exposed to a fire.

Once I put on my gas mask, how long 

will it last?

That depends on how much filtering capacity

the respirator has and the amount of hazard in

the air – the more chemical or biological hazard

in the air (higher concentration), the shorter the

time your filter will last. There is no absolute

time limit, and it will vary by each respirator

model's capacities and the concentration of the

hazard. 

QUESTIONS TO CONSIDER REGARDING

ANY RESPIRATOR YOU ARE CONSIDERING PURCHASING: 

• What protection (which chemicals and particles, and at what levels) does the respirator

provide? 

• Is there more than one size?

• Which size should I use? 

• How do I know if the gas mask or respirator

will fit? 

• What type of training do I need? 

• Are there any special maintenance or storage

conditions? 

• Will I be able to talk while wearing the respirator? 

• Does the hood restrict vision or head movement in any way? 

• Can I carry the device in the trunk of my automobile? 

• Is a training respirator available? 

Additional Information

For more information on OSHA’s rules and

requirements related to respiratory 

protection, visit OSHA’s website at

www.osha.gov/SLTC/respiratoryprotection/

index.html
This is an informational bulletin, advisory in nature, and intended to further the

safety and health of workers and employers. It does not impose any new compliance requirements. For a comprehensive list of compliance requirements of OSHA

standards or regulations, refer to Title 29 of the Code of Federal Regulations. This

information will be made available to sensory impaired individuals upon request.

The voice phone is (202) 693-1999; teletypewriter (TTY) number: (877) 889-5627.

U.S. Department of Labor

www.osha.gov

(800) 321-OSHA

For more complete information: