Reference Library

A dust mask may not have the same interpretation from one individual to the next, and manufacturers do not always use the same definitions.  A dust mask typically has one supporting strap, is not governed by federal or state regulations, and is not given a National Institute for Occupational Safety and Health NIOSH. Dust masks are not intended to be used while applying or working around toxic chemicals or aerosols.

A respirator, on the other hand, is a device to protect you from inhaling dangerous substances such as chemicals and infectious particles.  There are several different types of respirators, as described below.

Escape respirators are designed to be used only in an emergency, and only to escape from a dangerous area to a safe area.  There are several escape respirators on the market.  Many of them have a hood with a neck seal instead of a face piece.  The escape respirators are typically designed for a one-time use and for only a short period of time, typically from 15 minutes to 1 hour. 

Particulate respirator is the simplest, least expensive, and least protective of the respirator types available.  These respirators only protect against particles.  They do not protect against chemicals, gases, or vapors, and are intended for low hazard levels.

Chemical Cartridge/Gas Mask respirators are also known as “air-purifying respirators” because they filter or clean chemical gases and possible particles out of the air as you breathe.  This type of respirator includes a full face or half face mask, and a filter/cartridge (if the filter is in a metal shell it is called a “canister”).  Straps secure the face piece to your head.  These cartridges may have a filter (to remove particles), charcoal (to remove certain chemicals), both of these components, and/or other parts.  When you inhale, air is pulled in through the filter/cartridge and is purified as you breathe.

Gas Masks are effective only if the correct filter and/or cartridge (these terms are often used interchangeably) is used for a particular biological or chemical substance. You need to know what hazards you will face in order to be certain you are choosing the right filters.  Particulate respirators, filters, and pre-filters all work in the same way: by trapping solid and liquid particulates such as dusts, mists, and fumes.  They may be found in the form of a disposable particulate respirator or in the form of a pre-filter (half-mask and full-face respirators), which may be used in conjunction with a disposable chemical cartridge. These filters should be worn and changed in accordance with manufacturer’s instructions.  Selecting the proper filter or cartridge can become a complicated process.  Fortunately all manufacturers use the same chemical cartridge color coding system. 

• Acid Gas - White
• Organic Vapors - Black
• Ammonia Gas-Green
• Acid Gas and Organic Vapor - Yellow
• Multi-gas (protects against numerous gases and vapors) – Olive
• HEPA (P100) – A Particulate filter. (All others are for gases and/or vapors) – Magenta

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 to use and to maintain them. Also, the air tanks typically last an hour or less depending upon their rating and how hard you are breathing.

There are filters and cartridges that protect against more than one hazard, but there is no “all-in-one” filter that offers protection against all substances.  You may start by asking yourself the following questions:

1.)   Which respirator do I choose if I’m working around dusts, mists, fumes, or agricultural molds?  You can wear an N95 in almost any dust situation.  Exceptions:  If you are welding exotic metals (for example- magnesium or titanium) which give off toxic fumes and gases, you’ll need protection from an N100 or P100 HEPA type filter.  OSHA also requires HEPA respirator protection when coming in contact or in environments which can contain lead or asbestos.

2.)   What do 95 and 100 refer to in the N95 and P100 designations for disposable and non-disposable particulate respirators?  The numbers refer to the efficiency of the filter.  A 95 rating specifies a 95% filtration efficiency or better for particles larger than .03 microns. A 100 rating specifies at least a 99.7% filtration efficiency. N filters are "Not Resistant" to oil. R filters are "Resistant to Oil" and can be used for eight hours with chemicals and pesticides that contain oil. P filters are "Oil Proof" and can be used with oil and non-oil hazards; may be able to use longer than eight hours. As an example: a P100 filter would be strongly resistant to particulates which may contain oil and would have a filtering efficiency of at least 99.7%.

3.)   What is the difference between a particulate filter and a chemical cartridge?  Particulate respirators, filters, and pre-filters trap solid and liquid particles such as dusts, mists, and fumes.  They can be purchased in the form of a disposable respirator, a single use disposable particulate respirator, or in the form of a pre-filter, which may be used in conjunction with a chemical cartridge.  The filters must be used and changed in accordance with the manufacturer's instructions or when you first experience breathing resistance.

Chemical Cartridges-(gas and/or vapor removing cartridge type respirators) are filled with specially treated activated carbon which absorbs certain gases and/or vapors.  If you experience an odd taste or smell something different, or if your eyes, your throat, or your lungs feel irritated, it is time to change the chemical cartridge.  It is recommended that you schedule regular cartridge changes/replacements before you experience any symptoms to avoid being exposed to contamination.