Last Update 12/15/03

Gas Masks, Respirators and Escape Hoods

What is a Gas Mask or Respirator?

There are basically 3 types of gas masks or respirators.

Air-purifying respirator or gas mask as it is also known, protects the eyes as well as the mouth. A gas mask does NOT contain a supply of oxygen. It removes or neutralizes contaminants from inhaled air and must be used only in areas where there is sufficient oxygen to sustain life. The advantages of the gas mask is they easy to use and the cost is the least. The drawbacks to a gas mask are they can leak around the face seal from a poor fit or from a crack or hole in the mask rubber. You cannot have any facial hair if you want to get a proper seal with a gas mask. Also, children may have trouble getting a proper fit. Breathing resistance in a gas mask is often quite high and in some instances may be too difficult for a child or the elderly to overcome. This can result in a loss of air supply to the child and may place the child at greater risk. There is no gas masks currently on the market that have been designed or approved by the U.S. government for use by children and most gas mask companies do not recommend that gas masks be used by children. The gas masks that are currently on the market are not approved for use on animals. To have a gas mask fit an animal properly to form an airtight seal around the face area, it would have to be specifically designed for that animal. Gas masks are only effective when the hazard in question has been properly identified, the mask is properly fitted and used correctly, and used in areas containing sufficient oxygen to sustain life. ANSI Z88.10 provides guidelines on how to perform a proper fit test. Many chemical and biological agents can enter the body through the skin, so a hood and protective suit, including gloves and shoe coverings would be necessary for protection.

Supplied-air respirator. Uses the same sort of filter cartridge found in an air-purifying respirator above . However, instead of placing the filter directly on the mask and requiring the user's lungs to suck air through it, the filter attaches to a battery-operated canister. The canister uses a fan to force air through the filter, and then the purified air runs through a hose to the mask. The advantage is that the air coming into the mask has positive pressure. Any leak in the mask causes purified air from the canister to escape, rather than allowing contaminated air from the environment to enter. Obviously, positive pressure creates a much safer system, but it has two disadvantages. If the batteries die, so do you. The constant air flow through the filter means that the filter does not last as long.

SCBA (self-contained breathing apparatus) system. This is the tank you see firemen or SCUBA divers wear on their back. The tank provides constant positive pressure to the face mask. An SCBA provides the best protection but they are very heavy to wear and only hold 30 to 60 minutes of air, and you must have a way to refill these tanks. This system is very expensive and not really a good choice for home defense.

Filter For Gas Masks

Gas mask filters can use one or more of three different techniques to purify air:

Fitting, Testing and Care of the Gas Mask

Fitting the Gas Mask.

1. Loosen harness head straps.
2. Hold facepiece by straps and put chin in first.
3. Pull harness back over head.
4. Tighten lower straps first, by pulling end-tabs straight
back, not out. Tighten side straps the same way.
5. Push headband pad towards neck and repeat step 4.
If necessary, tighten the top strap(s) for best visibility and fit.

Air-Tightness Test

Perform this test each time the gas mask is put on to ensure a sufficient face-to-facepiece seal is achieved before exposure to a hazardous agent. Perform the test as follows:

1. Block off canister inlet using the palm of hand.
2. Inhale gently and hold breath for 10 seconds. If the seal is good, the facepiece will collapse and remain collapsed against face. Remove hand and breathe normally.
3. If the facepiece did not remain collapsed during the test, or any leakage is noticed, readjust straps and test again.
4. If this does not correct the leak, the mask will not provide protection. If the leakage is from the face seal, a different size mask may provide a good seal. If other than face seal leakage is detected, the condition must be corrected before performing another test.

ANSI Z88.10 provides guidelines on how to perform a proper fit test.

Gas Mask Care and Maintenance

Routinely inspect this gas mask for proper operation in anticipation of use in an emergency situation. Replace any components that are found to be defective. Look closely at the mounting thread for the filter and the head straps for excessive wear. If the face lens is badly scratched or yellowed get a replacement lens. You can clean the lens with a soft rag and window cleaner like Windex. To clean the mask, use a soft rag with a mild cleaner and warm water.

Using Your Gas Mask

The user should become familiar with the operation of their gas mask and ensure that it fits properly before use in an actual warfare agent encounter. Don't wait until you really need the mask to learn how to use it, you won't have the time.

When To Put The Mask On.

Put on your gas mask and protective clothing at first indication of the presence of a warfare agent. Follow warnings of local authorities, as the presence of a warfare agent may not be detectable by sight or smell. Follow directions of local authorities regarding where to go to seek shelter. Absent these directions, seek a secure place indoors and away from contaminated areas.

When To Take The Mask Off.

Do NOT remove gas mask or protective clothing in contaminated area. As instructed by local authorities (after agent dissipates or when safely away from contaminated area), decontaminate mask and clothing. Remove mask and clothing only after proper decontamination as instructed by local authorities.

When To Change The Filter.

The filter canister should be replaced after each use. During use, the length of time the chemicals in the canister will give protection depends both on the concentration of the agent and the rate of breathing. When the mask is properly adjusted, detection of agents having warning properties such as odor, taste, or eye, nose or throat irritation is an indicator that the canister is exhausted and must be replaced. Excessive resistance to inhalation is also an indicator that the canister must be replaced.

I would be leery of buying most surplus masks and filters, as they are just that surplus, either because they are no longer serviceable or out of date in most cases. I would avoid anything that I could not get a FRESH, newly manufactured filter for.

Finally, I would not count on interchangability of filters. In my experience, that is not the case. If your concern is solely bio hazard, you can get a mask with a HEPA/particle filter from someplace like Lab Safety. As a member of a WMD team sponsored by the USPHS, we use commercial, off the shelf stuff for NBC protection.

Regarding Anthrax, the type of infection following a terrorist incident would be pulmonary, spread by inhalation of the spores. Cutaneous infection is only encountered in slaughterhouse personnel that handle infected meat and hides.

I would again caution people against relying on flea market surplus junk. You are betting your life on something that a governmental agency junked and has been stored under less than ideal conditions. My federally sponsored teams use a commercially available PAPR, a powered respirator. That is not necessary for most people. MSA makes a domestic terrorism full face respirator that is listed in the Lab Safety catalog.

-Jeffery S. Anderson, M.D.

Micronel Safety M95 Gas Mask

The Micronel M95 is considered one of, if not the best gas mask available.

The M95 respirator embodies the highest levels of efficiency and comfort in model NBC protection. Experience coupled with the latest innovations in respiratory protection created a product that far exceeds the requirements of international standards. The advantages of advanced computer-aided design have been used in the development of the M95 to produce a high-quality product of outstanding anatomical accuracy. The normal protection factor is >10,000. The M95 gas mask is designed for easy maintenance, which in turn ensures reliable performance.

Wearer Acceptability
Due to extremely low breathing resistance, the M95 mask and filter are comfortable to wear even for long periods, without effecting user performance. Light in weight, the mask weighs less than 500g, 720g with filter. Small inner mask reduces dead-space to a minimum (CO2 content of the M95 mask is 0.7%). The respirator is easy to don and doff (donning test: 10 seconds). The stretch properties of the polyester/Lycra head-harness enhance wearer comfort, particularly over long periods. Extremely wide field of vision (even downwards), due to the close-fitting design of the mask.

High-Quality Materials for Maximum Protection
Halo-butyl rubber used for the facepiece is specially engineered to enhance resistance to all known chemical and biological warfare agents. Silicone inner mask provides comfortable fit against the skin, and all materials are tested to withstand demanding field operations. Elastic head-harness is resistant to chemicals and aging. The filter canister is made from reinforced polyamide for high impact resistance, and it has excellent fire retardant properties with long storage life

Practical Design and Construction.
Excellent fit and user comfort are the result of computer-aided design (CAD). Anatomical accuracy of the design is based on a wealth of facial-form data. The facepiece has filter connections on both sides in order to facilitate left or right handed operation. Spectacle frames for prescription lenses and a hoseless, leakproof drinking device (intake of liquid 250ml/min.) are just some of the special features.

The Safety NBC Filter Protection
Chemical and biological warfare agents such as saran and other nerve gases, mustard gas, cyanogen, arsine, phosgene. Radioactive and highly toxic particles and aerosols, bacteria and viruses. Many industrial gases, organic gases and vapors, inorganic gases and vapors (e.g. chlorine, hydrogen cyanide, hydrogen sulfide, organic and inorganic acids, such as formic acid, sulfur dioxide, hydrogen fluoride and hydrogen chloride).

Technical Data For M95 Gas Mask:

Materials - Polyamide
Face piece - Halo-butyl rubber
Inner mask - Silicone
Lenses - Polyamide
Plastic parts - Durable thermoplastics
Weight with filter - 700 grams
Protection factor - 10 000

Technical Data For M95 Filter:

Height - 90 mm
Diameter - 109 mm
Weight - 250 g
Thread - EN148 (40mm)

M95 Accessories:
MTC-1 FILTER- This is an upgrade from the standard M95 Filter that comes with the mask. The M95 is an excellent filter and will save your life. However, the MTC-1 is a bit better for its break-thru time. (The time it takes particles to leak thru filter over time) This is the best filter available on the planet. $33.00.

SPECTACLE KIT (Allows user to mount prescription lenses securely inside mask) $15.00.

DRINKING BOTTLE: Specially designed canteen type bottle that fits into masks drinking device. $20.00.

Best price is - $230.00 each w/1 filter. NBC Filter $21.00 each at Botach Tactical. Note: Please check for current price and availability.

Manufacturer point of Contact - Micronel Safety Products

MSA Gas Masks

Advantage 1000 CBA/RCA MASK

These masks are effective against a variety of chemical warfare and biological agents. They're made of super-soft Hycar™ rubber for superior comfort. A fully elastic, six-point head harness adjusts easily for the correct fit--easy to put on and take off without pulling hair.

Specifications:

Notes - The MSA Advantage 1000 Chem/Bio gas mask is the same military mask (MCU-2/P) that was used by our troops in the Desert Storm war. MSA was founded in 1914 and have been supplying gas masks to the U.S. military and other customers since World War I.

Best price is - Mask is $169.99, NBC filter $44.99 each at Ranger Joe's. Mask is $189.99, NBC filter is $49.99 at U.S. Cavalry. Mask is $199.99 at Brigade Quartermaster. Mask is $201.15 at Lab Safety. Note: Please check for current price and availability.

MSA Millennium Chem-Bio Mask

These masks are effective against a variety of chemical warfare and biological agents. They're made of super-soft Hycar™ rubber for superior comfort. A fully elastic, six-point head harness adjusts easily for the correct fit--easy to put on and take off without pulling hair.

Specifications:

Notes - The MSA Millennium Chem/Bio gas mask is the same military mask (MCU-2/P) that was used by our troops in the Desert Storm war. MSA was founded in 1914 and have been supplying gas masks to the U.S. military and other customers since World War I.

Best price is - $266.00 at Botach Tactical. $333.15 at Lab Safety. Note: Please check for current price and availability.

Manufacturer point of Contact - MSA

MCU-2/P Chemical–Biological Mask (USAF Military Issue)

The MCU-2/P Chemical–Biological Mask is used by U.S. Air Force ground crews and aircrews when not in flight. This protective mask is constructed of molded silicone rubber facepiece material, and an integral, molded, polyurethane, one-piece panoramic lens is bonded to it. Filtration is provided by one C2A1 canister mounted on either side of the facepiece. The primary voicemitter is located over the mouth area with a secondary voicemitter in the cheek area to utilize telephone handsets.

The mask incorporates a drinking tube, which connects to the M1 canteen cap. The mask has a six-point, adjustable head harness suspension made of elastic, which comes together in the center head back into a rectangular patch of woven material. The mask comes in three sizes: small, medium, and large. Accessories include a carrier bag, a butyl-coated nylon cloth hood, outserts to protect the lens in storage, and a waterproof bag.

Carry case for the MCU-2/P. Gas mask should be kept outside of bag unless threat is imminent; over time and changing weather visor may develop cracks or warp if kept compressed in bag.

The filters for the MCU-2/P and the M40 military gas mask are called C2A1 filters. See pic below. SEALED NATO U.S. Military C2A1 NBC (Nuclear, Biological, Chemical) canister filters. All of these filters are sealed INSIDE of VACUUM AIR SEALED METAL CANS. These filters are standard NATO filters (meaning they have a 40mm thread), and will FIT JUST ABOUT ALL CURRENT MASKS, including the ISRAELI CIVILIAN MASK, ISRAELI ARMY M15 mask, CANADIAN M69/C3/C4 masks, U.S. ARMY M40/M42 masks, U.S. AIR FORCE MCU-2A/P mask, RUSSIAN M41 and GP5 masks, BRITISH S10 mask, and any other current mask that uses standard 40mm NATO canister filters.

Prices right now are about $25.00 to $35.00 USD on Ebay for one C2A1 filter. These filters are good for 6 to 8 hours in an attack, so you'll need several. Try and get the carry case as part of you gas mask deal/purchase. Most of the C2A1 filters selling on Ebay are past their shelf life or very near it.

You can buy fresh new NBC M95 filters, which fit the MCU-2/P mask, at Botach Tactical for $21.00 each.

MCU-2/P gas masks are going for about $150 to $200.00 on Ebay. Just type "Gas mask" or the model number of the mask into the search window. Make sure you use a credit card so you don't get burned. DO NOT send a personal check, cashier's check or money order. I have used PayPal and Bill Point to order items on Ebay and they work good.

FILTERS: M13 series: should not be used for NBC protection. C2A1 canister filters: Racal Filter Technologies of Canada manufactures these. The year of manufacture is determined by examining the stamped code on the green can the filters come packed in and is two digits after the letters RFT. Example: RFT94XXXXX was made in 1994, the X is the lot number.

If left sealed in the green can under reasonable storage conditions the shelf life should be between 10 and 18 years. Realistically expect 9 to 12 years. C7 canister filters: Same as information for C2A1 filters, also it is rumored that a different chemical mix may give these a slightly longer shelf life.

Flodins NBC-37 canister filters: Date of manufacture is stamped on canister itself. Original filters from the factory are in green cans similar to the C2 series, many militaries repackage them with the plug seals in place in clear plastic bags to save weight in transit. Shelf life should be similar to C2A1.

One advantage of a military issue mask is the canteen adapter that allows you to drink from your canteen with the mask on. These canteen adapters are only several dollars each.

M17 and M17A1 US Military Issue Gas Mask (Obsolete)

M17 and early M17A1s: obsolete and potentially unsafe due to parts failure and deterioration. Potentially useful filtering dusts. Post-1978 M17A1s and M17A2: Potential use only with fresh filters against riot agents and dusts. Not safe for NBC protection. This is the old Vietnam era military issue gas mask

M40 and M40A1 Chemical–Biological Mask (U.S. Military Issue)

Mask, Chemical–Biological: Field, M40. The M40 Chemical–Biological Field Mask series represents the latest generation of protective mask to be issued to the U.S. military. The inner layer of the facepiece is composed of molded silicone rubber that fits tightly against the face, and has an inturned peripheral seal, which increases comfort and fit. The mask’s two ridged eyelenses are approximately 35% larger than the type used in the older M17A2, thus providing a better field of view. Filtration is provided in the M40 mask by one C2A1 filter canister, which, at the user’s convenience, can be mounted on either cheek.

Original M40 (late 1980s-early 1990s) has silicone facepiece prone to HD penetration. This does not disqualify the mask from use but a "second skin" hood should always be in place. M40A1 is an excellent mask with no major concerns at this time.

Two canisters may be mounted on both cheeks for special purpose activities such as explosive ordnance disposal or technical escort. The standard C2A1 canister will protect against 16 attacks of nerve and vesicant agents. Any other standard thread (40mm), canister issued by North Atlantic Treaty Organization (NATO) countries will fit the M40 mask.

Communication is provided by two voicemitters. One is mounted in the front to allow face-to-face communication; the second is located in the cheek to permit the use of a radio telephone handset. A drinking system consists of internal and external drink tubes; the external tube has a quick-disconnect coupling that connects with the M1 canteen cap. A six-point, adjustable harness with elastic straps located at the forehead, temples, and cheeks comes together at a rectangular head pad.

The M40 mask comes in three sizes: small, medium, and large. Optical inserts are provided for vision correction and outserts are available to reduce fogging and sun glare and to protect against scratching. A check valve on the nosecup prevents exhaled air from fogging the lenses inside, and an air deflector directs inhaled air over the lenses, which also helps prevent fogging. Accessory items available include a carrier, a hood to protect the neck areas, and a waterproof bag.

These gas masks are going for about $150.00 to $200.00 on Ebay. Just type "Gas mask" or the model number of the mask into the search window. Make sure you use a credit card so you don't get burned. DO NOT send a personal check, cashier's check or money order. I have used PayPal and Bill Point to order items on Ebay and they work good.

Identifying M40 series Masks. Thanks to D. Toscano for these tips.

Information is taken from personal experience as well as US Army TM 2-4240-300-20&P. This guide only covers characteristics to check to verify the identity of a mask. Some eBay sellers try to sell old M40s as "M40A1" models when in fact they are not the same mask at all.

HOODS:

M40 is issued with a hood with integral black butyl rubber "second skin" facepiece and hook-and-loop retention fasteners below the "nose" area of the mask. M40A1 series issued with Quick Doff Hood, characterized by elasticized round facepiece opening without integral "second skin." Has quick-release tabs on the underarm straps.

"SECOND SKINS":

M40 second skin is integral to hood as mentioned above. M40A1 has close-fitting second skin without hook-and-loop fasteners, not integral to hood. Has small rubber tabs to help hold it onto the mask's facepiece. USMC M40A1 variation is same except has hook-and-loop fasteners below "nose" area of mask.

NOSECUPS:

M40 has black rubber nosecup. M40A1 has improved green rubber nosecup.

Mask, Chemical–Biological: Field, M42

The M42 Chemical–Biological Field Mask is the same series as the M40. The materials of construction and the basic features are identical, but the M42 protective mask is used by combat vehicle crews. Filtration is provided by a C2A1 canister attached to the mask by a corrugated hose; the canister is housed in a specially designed canister carrier. The M42 integrates with the combat vehicle filtration protection system. The M42 also has a dynamic microphone that integrates with the combat vehicle via a microphone cable.

Israeli Gas Masks.

Israeli civilian Issue gas mask.

Many if not all Israeli gas masks have been exported from Israel due to their age. Also many of these masks are being sold, innocently I assume, with a PRACTICE filter that is ONLY for tear gas. From what I have read if an Israeli filter has a BLUE string it is a practice filter. Yellow string filters are NBC filters, (nuclear, biological, chemical).

These masks are also known to fog up badly, you can't drink from them and your hair gets caught in the head harness when donning the mask.

These gas masks are going for about $40.00 to $100.00 on Ebay. Just type "Gas mask" or the model number of the mask into the search window. Make sure you use a credit card so you don't get burned. DO NOT send a personal check, cashier's check or money order. I have used PayPal and Bill Point to order items on Ebay and they work good.

Current issue Israeli Military gas mask is the M15.

This mask has larger eyepieces better visibility antifog ports on the lens, and a drinking tube to drink while wearing the mask(far superior to the civilian Israeli gas mask). Includes a new Military, NBC rated, sealed filter and drinking tube. One size fits all totally adjustable.