In hostile situations you sometimes find yourself faced with airborne diseases, chemical fumes, smoke, and dust, and in any danger the first step to safety is prior preparation. Gas masks and respirators provide the most effective protection against these threats. However, they are not a guarantee of safety; the most important aspect of protection is still timing. If a terrorist organization or rival army releases a chemical weapon chances are you will not know about it until it is already too late. You cannot wear an air filter 24/7, it would interfere with your daily life and you would have to carry a large supply of replacement filters with you. In addition to being somewhat restrictive, the systems need to be cared for and maintained. You should take the time to receive some training in using the system you purchase. After you are comfortable with your knowledge of your chosen system, it is important to regularly check your equipment and practice donning it efficiently and effectively.

Filters and how they work

Image Courtesy of How Stuff Works.

Particulate Filter

A particulate filter works by having finely woven fibers that have gaps as small as .3 microns wide. This is large enough to allow the passage of air, but blocks small and large particulate matter. However, against smaller hazards such as bacteria and viruses such as anthrax, it provides insufficient protection.

Chemical Absorption Filter

This works by absorbing the contaminant before it passes into our airflow; the most common form of this is activated charcoal, an extremely high-porosity version of charcoal, capable of absorbing many chemicals while still allowing the passage of air.

Chemical Reaction Filter

This filter works by supplying a chemical that reacts with the contaminant to neutralize it. Notably the first time use against a biological threat in war was in WWI when some enterprising Canadians discovered that the ammonia from urine negated the effects of chlorine gas used as a chemical weapon by the central powers. [1]

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Types of Respirators

Disposable Dust/Particulate Respirators

Image Courtesy of Jamestown Distributors.

Description

These respirators are made of various recyclable materials such as wool, glass, plastic, and cellulose these masks bond to the harmful materials prohibiting them from entering into you. Multiple levels of effectiveness are available, but the only ones worth purchasing from the standpoint of hazard protection are those that provide 95% protection against small particles and even some viruses. [1]

Pros

Weighs virtually nothing and the low price and easy availability make this a quick and simple way to protect your self from low level pathogens.

Cons

It only increases you chances of fighting pathogens and does not fully prevent them from getting to you, due to an incomplete seal. May become harder to acquire and replace post apocalypse, although they are sold in bulk. Their partial face coverage and incomplete seal prevents them from providing full protection against the dangers you may encounter.

Maintenance

No Maintenance is needed for these. Throw them away when they become difficult to breathe through.

Initial Costs for a Case

Cases of 20 go for around 40 dollars.

Directions for use

Pull the lower elastic band over your head, and place it below your ears. Do the same with the upper elastic band, leaving it above ear level. Ensure that the mask fits tightly.

Image Courtesy of New Pig Corporation.

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Half-Mask Air-Purifying Respirators

Image Courtesy of Global Safety Co.

Description

The basic unit consists of a rubber material that fits snugly over the nose and under the chin. These masks use several different types of filters to protect from various threats.

Filters

• HEPA filter: Protects against small particulate matter, such as asbestos and some airborne radio
• Pesticide: Protects from low levels of water-vapor borne toxic contaminants, such as pesticides.
• Mercury Cartridge: Protects from low levels of metallic vapors such as mercury.
• Organic Vapor Cartridge: This filter provides protection from organic based vapors such as nail polish remover (acetone) and some paints.
• Acidic Gas\Mist Cartridge: This filter protects from low levels of natural gas vapors, gasses, and other slightly acidic airborne contaminants.
• Combination Cartridge: This filter is for protection in an environment that may contain various types of hazards.

[4]

Pros

Light weight, low initial and maintenance cost. Easy to care for and maintain. Protects against low level airborne pathogens.

Cons

While it filters better then the disposable dust particulate respirators it will only protect from low-level hazards and particulate. It provides no protection for the skin or eyes, and like all filters partially restricts breathing.

Maintenance

• Mask itself: Remove the filters, cartridges, and attachments from the mask and then immerse the mask into warm water and soap. Scrub the equipment and then rinse with water. The mask should come with a list of safe disinfectants to use. Use them after each use and then either let the mask air dry or dry it with a lint free Cloth.

[4]

Initial Costs for a decent unit

It costs around 35-50$ for the respirator with an additional 50-100 dollars for the filters.

Directions for use

It is important that the mask be donned before entering the hazardous environment. Place the bottom straps over your head and hook them around your neck with the top strap secured in place at the top of your head. It is important to ensure you have a good seal against the face, but avoid causing bruising. A common technique for testing the seal is a "breath test". First you should cover the exhalation valve with your hand or a piece of paper and then blow into the respirator and the mask should lift or pull away from the face before the air comes out. For the second portion of the test, cover the respirator and inhale gently and the mask should collapse slightly onto the face. If during the exhalation test air escapes without the mask moving or deforming, or during the inhalation test you can breathe in without deforming the mask, the seal is incomplete. These checks should be performed before every foray into a hazardous environment. While these tests are not a guarantee of a perfect seal, they are sufficient for protection against hazadous environments.

Image Courtesy of Federal Highway Administration.

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Full Face Mask Air-Purifying Respirators

Image Courtesy of Lab Safety.

Description

Similar to the Half Mask Air-purifying respirator, it differs in the addition of an upper faceplate to cover the eyes as well. It fits snugly under the chin and ends above the forehead. [6] Different brands come in different designs, varying from single-piece faceplates to individual eyeholes in an opaque frame. The full face mask uses the same filters as the half face mask,with the added protection of the faceplate allowing for the creation of a better seal and also protecting the delicate eyes.

Pros

Provides greater protection from splashing fluid and airborne contaminants, including viruses and bacteria. The eyes often serve as an entry for disease, even when the respiratory entryways are blocked.

Cons

Heavier then the half mask, the full mask is more costly and some wearers may experience increased irritation due the increased coverage. It takes longer and can be more difficult to don than a half mask, and users will encounter difficulties when trying to put this style of mask on over prescription glasses, as the glasses frame will prevent the mask from forming a good seal.

Maintenance

• Mask itself: Remove the filters, cartridges, and attachments from the mask and then immerse the faceplate into warm water and soap. Scrub the equipment and then rinse with water. The mask should come with a list of safe disinfectants to use. Clean after each use and then either let the mask air dry or hand-dry it with a lint free cloth. Vinegar works well to clean the face plate of any imperfections or solid build-up.

Initial Costs for a Decent Unit

Average price for a mask ranges from $150 to $350, plus the approximately $100 cost of future filters and cartridges.

Directions for use

It is important that the mask be donned before entering the hazardous environment. If you are wearing glasses, remove them prior to placing the mask over your head. Place the bottom straps over your head and hook them around your neck with the top strap secured in place at the top of your head. It is important to ensure you have a good seal against the face, but avoid causing bruising. Just like the half mask, a common technique for testing the seal is the "breath test". First you should cover the exhalation valve with your hand or a piece of paper and then blow into the respirator and the mask should lift or pull away from the face before the air comes out. For the second portion of the test, cover the respirator and inhale gently and the mask should collapse slightly onto the face. If during the exhalation test air escapes without the mask moving or deforming, or during the inhalation test you can breathe in without deforming the mask, the seal is incomplete. These checks should be performed before every foray into a hazardous environment. While these tests are not a guarantee of a perfect seal, they are sufficient for protection against the majority of hazardous environments.

Image Courtesy of Federal Highway Administration.

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Powered Air Purifying Respirators

Image Courtesy of Safety Saves Administration.

Description

Powered Air Purifying Respirators work similarly to the manual respirators with one large difference. Powered units contain a fan that pulls air through the filter and into the mask. The filter is placed in front of the fan. [7]

Pros

Powered respirators are much easier to breathe in than non-powered ones. The fan keeps a constant stream of air passing through the filter, cleaner than the air from non-powered masks.

Cons

The battery adds some substantial weight, and if the battery dies while you are wearing the mask you risk suffocation if you cannot reach a safe area fast enough.

Maintenance

• Mask itself: Remove the filters, cartridges, and attachments from the mask and then immerse the faceplate into warm water and soap. Scrub the equipment and then rinse with water. The mask should come with a list of safe disinfectants to use. Use them after each use and then either let the mask air dry or dry it with a lint free cloth. Vinegar works well to clean the face plate of any imperfections. Use a long brush to clear the hose of any dirt and grime with more warm water.
• Battery: Some systems use commonly available replaceable batteries, while others have rechargeable batteries.
• Fans: While fans do not needed to be changed quite as frequently as batteries and filters or cartridges, it is still a good idea to clean it at least once a week, or once a day for the more cautious.

Initial Costs for a decent unit:

Prices range from $350 to $550 for the initial unit, plus costs for future filters which could run from $50 to $100 each.

Directions for use

As with all atmospheric protection, the mask must be donned before you encounter the threat. Hook the bottom strap around your neck and secure the top strap at the top of your head, making sure to pull your hair back to prevent it from breaking the seal. If you wear prescription glasses make sure to take them off before putting on the mask. Adjust the straps after placing it on your head until it is snug on your face. Make sure the hose connected to the battery unit is not kinked and place it either on your belt or on another area specified on the unit. [7]

Image Courtesy of OSHA Administration.

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SCBA (Self Contained Breathing Apparatus)

Image Courtesy of Wassaic Fire Rescue.

Description

Providing the user air from a pressurized tank on their back, SCBA units consist of an air tank connected to a full face mask by a long hose. Because of this, SCBA units do not need filters. This is what firefighters use when they enter burning buildings.

Pros

Provides the greatest protection from air contaminants, by relying on a source of pure air rather than filtering the contaminated air. If properly sealed, little or no air should enter the mask from the outside.

Cons

Weight, cost, and maintenance time are all higher then other options. SCBA systems will only provide you with a maximum of one hour of air, even with the larger canisters.

Maintenance

• Mask and Hose: Check to ensure that all parts are present. Carefully inspect each separate part for dirt, cracks, cuts, tears, abrasions, deterioration and heat or chemical damage. Once you are sure all parts are present and in good condition, verify the faceplate has a good seal by placing it against your face and breathing in. The mask should tighten against your face when you breathe in. Check the regulator hose and connection for any obvious damage.
• Canister and Harness: Verify the canister retention system and harness hold the canister firmly in place and that the harness straps are set so that it can be quickly and easily pulled on. It is very important that the canister be charged to the manufacturer’s levels. Anything under 95 % of this level and you should replace it with a different canister. If possible assure that the canister has recently (within the last 3 -5 years depending on the manufacturers preference) had its hydrostatic test (In a hydrostatic test the cannister is filled with a dyed liquid at the proper pressure and checked for leaks. See here). Inspect the canister itself for damage including dents, cuts, blemishes, weakened areas, cracks, and indications of heat or chemical damage. Check the composite hoop wrapped material for any damage and if you discover any immediately dispose of the canister as the wrapping gives it its strength. Ensure the cylinder valve hand wheel is tightened; If it is loose you may damage the O-ring. Perform a pressure test by fully charging the system and then comparing the canisters pressure gauge to the remote pressure gauge and ensuring they read within 10% of each other. Next open the bypass valve to ensure it works properly and close it after checking. If the system has a PASS system on it (a system used by firefighters that emits a high pitched audio alert if they do not move for a certain amount of time) check it for errors, replacing batteries as necessary.

[3]

Initial Costs for a decent unit

Initial costs range from $1500 to $1800.

Directions for use

Open the canisters flow valves and then pull tank and harness onto back, snapping it into place.Ensure that there is little to no wiggle room to it. Pull the mask over your face with the lower straps lying comfortably at the nape of your neck, and place the top straps at the top of the back of your head. Ensure the hose isn’t kinked, and you’re ready to go. [3]

For a video depiction of how to use an SCBA system, see How to use a SCBA at Wonder How To.

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Rebreathers

Image Courtesy of DiveBuddy.com.

Description

Similar to SCBA units, rebreathers are notably different in the fact that they can recycle some of the exhaled air back into breathable oxygen, to augment the air stored in the tanks. ([9]) This makes it possible to breathe clean air for longer, with the same size tank.

Pros

Lighter then an SCBA unit for the same breathing time, but provides the same amount of protection.

Cons

Rebreathers still weigh and cost substantially more compared to the other methods available.

Maintenance

For the most part, maintenance is the same as the SCBA. However, you may wish to check some additional things. To check for a positive pressure leak fill the system until the relief valve releases then let the system sit and ensure no air leaks out. For a negative air leak, evacuate all of the gas from the breathing tube then kink it. Leave it alone for five minutes and if it unkinks on its own you have a negative air leak. [9]

Initial Costs for a decent unit

The initial price for a rebreather ranges from $5000 to $12,000.

Directions for use

After verifying that the rebreather is properly prepared, pull the tanks onto your back like a backpack and open the flow valve. Take a couple of breaths through the mouth piece (face mask if using a full face mask variety) to ensure air is flowing and then the rebreather is ready for use.

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Self Contained Self Rescuer

Image Courtesy of Alphanr.

Description

Relatively small in size and light in weight, SCSRs provide the same degree of protection as a SCBA without the downside of of limiting your movement. Similar to the SCBA, an SCSR provides the user with around 1 hour of oxygen. [10]

Pros

Light weight and compact design does little to limit your movement, while still providing the same level of protection as an SCBA.

Cons

Still pricey at around 800-1200 dollars a unit, with a required refill after an hour of use.

Maintenance

Every 30 days you should visually inspect the SCSR for any cracks or broken parts. When not in use, the SCSR should be kept in an environment of moderate temperature within the manufacturer’s guidelines. [10]

Initial cost of the unit

The cost of an SCSR runs between $800 and $1200, plus any future maintenance.

Directions for use

An SCSR can be activated in a few easy steps.

• Step one: Activate the oxygen supply
• Step two: Remove the plug and insert the mouthpiece into your mouth.



• Step three: Place nose clips over your nose.



• Step four: Place goggles on head and place strap around your neck, ensuring that the mouthpiece fits securely and does not move. The SCSR is now ready for use.

Images Courtesy of MSHA and NIOSH organizations. [11]

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Critical Maintenance Checklist

Filters and Cartridges

Some filters and cartridges come with meters that let you know when they need to be replaced. However, for those that do not come with a way of checking their viability, you should replace them by or before their ETE(estimated time of expiration). While in use, if it becomes excessively difficult to breath through the mask you should immediately replace the filter or cartridge.

Fogging

With all full face respirators you will face the problem of fogging. Fogging occurs when the heat inside the mask differs from the outside, causing condensation to form and obscure your view. There are a few solutions to this problem.

• Anti-fogging solution, e.g. Aquasphere Antifog Solution

• Saliva can be used to temporarily prevent fogging, but must be reapplied often.

• Some shampoos can be used to prevent fogging, e.g. Johnsons No Tear Baby Shampoo

• A solution of white (distilled) vinegar and hot water can serve as a home-made anti-fogging solution when rubbed on the lens.

• Detergents can be used for anti-fogging, however not all agree on this. Detergents are water soluble and thus can smear, decreasing visibility through the lens.

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Limitations

Gas masks and respirators are not without their limitations. Young children and people with facial hair, such as beards and side burns, will not be able to use a system as they will be unable to form a proper seal on their face. For facial hair, this can be solved by shaving and for young children some companies make special masks, however some of these are not as effective as full-sized adult masks. It is unlikely that you will be able to find a mask sized for an infant. The most important limitation is that you cannot wear a system 24/7, and thus you can only use a system to its full potential if you know of the danger ahead of time, giving you the time you need to don your mask.

Additional Notes

Improvised Filters

While making an improvised filter out of damp cloth can provide temporary protection against some contaminants, it is not viable for long-term use or protection against small contaminants, such as biological or chemical hazards. This type of filter will only work temporarily, and only provides protection against large particle contaminants. If using this method for smoke or dust it is recommended to make the cloth as damp as possible and not waste any time leaving the contaminated area.

Surplus Masks

This section represents the opinion of a the author and a number of users of respirators and gas masks. While it is not to be taken as the absolute truth, it is better to be safe than sorry. If you have a surplus mask and can prove that it is functional, then there is no reason not to use it. If you don't have any other choice, a surplus mask (even untested) is better than no protection at all.

Three words are all that are needed when considering buying a surplus gas mask for cheap: Don't Do It. Surplus masks are sold as such because they are either cheaper, lower quality, have been discontinued because they are not as good as the ones currently on the market, or the product has some defect in it that makes it less desirable. When you are shopping for a gas mask you need to consider that this is going to be protecting you from contaminants in the air all around you. You wouldn't skimp on getting cheaper airbags for your car, so don't skimp on your gas mask.

Work Cited

1: Types of Gas Masks:

http://ehs.ucsc.edu/industrial_hygiene/pubs/resp/resptype.htm

2: Product sales numbers (prices):

http://www.highperformancesafetyproducts.com/50416-00000.html

3: Proper Maintenance on a SCBA:

http://dev2000.firefighternation.com/article/firefighter-safety-and-heal...

4: Half-Mask Air-Purifying respirators:

http://ehs.unl.edu/sop/RPP_SOP_APHalfMask.pdf

5: Image showing how to use the Half-Mask Air-Purifying Respirator:

http://www.cdph.ca.gov/programs/olppp/Documents/respirator.pdf

6: Full Face-Mask Air-Purifying Respirators:

http://ehs.unl.edu/sop/RPP_SOP_APFullFaceMask.pdf

7: Powered Air Purifying Respirators:

http://ehs.unl.edu/sop/RPP_SOP_PAPR.pdf

8: Supplied Air Respirators:

http://ehs.unl.edu/sop/RPP_SOP_SAR.pdf

9: Rebreather Maintenance:

http://www.technologyindepth.com/sentinel/Sentinel%20Rebreather%20Mainte...

10: Self-Contained Self-Rescue Kit

http://bestcoaltrading.blogspot.com/2010/09/self-contained-self-rescuers...

11: Self-Contained Self-Rescue Kit Instruction Manual

http://www.msha.gov/S&HINFO/USERNOTE/PORTPAK.pdf