Because of the problems with SCBA systems, any respirator that you are likely to use will have a filter that purifies the air you breathe. How does the filter remove poisonous chemicals and deadly bacteria from the air? Any air filter can use one (or more) of three different techniques to purify air: Why are drone pilots leaving the military? Does the U.S. military have rules about tattoos? How Post-traumatic Stress Disorder Works 5 Technical Innovations in the War on Terrorism Particle filtration is the simplest of the three. If you have ever held a cloth or handkerchief over your mouth to keep dust out of your lungs, you have created an improvised particulate filter. In a gas mask designed to guard against a biological threat, a very fine particulate filter is useful. An anthrax bacteria or spore might have a minimum size of one micron. Most biological particulate filters remove particle sizes as small as 0.3 microns. Any particulate filter eventually clogs, so you have to replace it as breathing becomes difficult.

A chemical threat needs a different approach, because chemicals come as mists or vapors that are largely immune to particulate filtration. The most common approach with any organic chemical (whether it be paint fumes or a nerve toxin like Sarin) is activated charcoal.(See this Question of the Day for details on how charcoal is made.) Activated charcoal is charcoal that has been treated with oxygen to open up millions of tiny pores between the carbon atoms. According to Encyclopedia Britannica: The word adsorb is important here. When a material adsorbs something, it attaches to it by chemical attraction. The huge surface area of activated charcoal gives it countless bonding sites. When certain chemicals pass next to the carbon surface, they attach to the surface and are trapped. Activated charcoal is good at trapping carbon-based impurities ("organic" chemicals), as well as things like chlorine. Many other chemicals are not attracted to carbon at all -- sodium and nitrates, to name a couple -- so they pass right through.

This means that an activated-charcoal filter will remove certain impurities while ignoring others. average cost of air conditioning duct cleaningIt also means that, once all of the bonding sites are filled, an activated charcoal filter stops working. lowest drop base air cleanerAt that point you must replace the filter.can air purifiers help with cigarette smoke Sometimes, the activated charcoal can be treated with other chemicals to improve its adsorption abilities for a specific toxin. The third technique involves chemical reactions. For example, during chlorine gas attacks in World War I, armies used masks containing chemicals designed to react with and neutralize the chlorine. In industrial respirators, you can choose from a variety of filters depending on the chemical that you need to eliminate.

The different filters are color coded by NIOSH standards for things like acids and ammonia. See this page for details. found on this site.Edit ArticleHow to Make a Gas Mask Three Parts:Making a Gas MaskMaking an Air Filter for your MaskTreating Exposure to Gases and ChemicalsCommunity Q&A Whether you are want to defend yourself from the apocalypse or against a round of police tear gas, having your own gas mask prepares you for any airborne chemicals you might encounter. While professional gas masks are much more reliable, creating your own mask in a pinch is an easy way to stay safe. It won't protect you against everything, but a homemade gas mask can help protect your face and lungs in an emergency. Know the difference between gas and particle contamination. Tear gas is actually a dust that is sprayed into the air, whereas biological weapons are generally gases. While it is incredibly difficult and expensive to completely protect yourself against gases, you can easily create a barrier against particles at home.

Toxic ash from volcanoes, tear gas, and dust are all particle contaminates. Cut the bottom off of a transparent 2-liter soda bottle. Cut a U-shaped opening for your head. Use a marker to draw a “U” across the front of the bottle, cap side down. This needs to fit snuggly across your face, stopping roughly at your temple and below your chin. Make sure you leave 5-6 inches between the bottom of your cup and your chin. Cut along your outline with your razor blade. Start smaller than you think you need – you can always cut more away later. The bottle should fit snuggly across your face, as this prevent gas from getting into your eyes. Create a protective seal around your face with rubber foam. Glue 1 inch of rubber form insulation around the edges of your gas mask to create a seal. This will keep contaminated air away from your eyes and nose. Take your time with this step, trying on your mask multiple times to make sure it sits snugly across your face. You can purchase rubber foam online or at large hardware stores.

If you can’t get your hands on rubber foam, use several layers of tape around the edges, or strips of fabric from an old t-shirt. Remove the elastic bands from your hospital mask. Staple the elastic bands to your mask. Push the hospital mask into the bottom to the bottle. This is your filtration device. Place the hospital mask, preferably an N95 particulate mask (available online or at a nearby health supply store), at the bottom of your gas mask. Seal the edge of the mask to the bottle with glue to prevent air from bypassing the mask. Wear your new gas mask. Attach a homemade air filtration system to your mask to protect from some gases. Cut off the top of a 1-liter bottle. Fill the bottom of the bottle with 3–4 inches (7.6–10 cm) of activated charcoal. Cut the bottom off another 1-liter bottle. This should be the same size bottle as before. Slice 1–2 inches (2.5–5.1 cm) from the bottom, leaving as much of the top as you can.

Leave the cap on. Fill the top of the bottle with 3-4 inches of pillow stuffing. This will remove any physical contaminants, like dust, ash, or tear gas, from your air. You can also use strips of old t-shirts, socks, or cotton balls. Slide the bottles together and tape them shut. If you used the same sized bottles you can slide one into the other, creating a seal. Tape the bottles together so they stay shut. This is your air filter! Poke 6-7 holes in the charcoal end of your filter when you’re ready to use it. Using a razor blade, cut holes in the bottom of the filter to allow air in. Activated charcoal will absorb moisture from the air if left uncovered, making it useless, so only cut the holes when you need the filter. Use a rubber hose to connect the bottom of your air mask to your filter. The easiest way to connect your filter to your gas mask is with an old vacuum hose. Clean it with soap and water and then attach it with duct tape around the ends of your filter and gas mask.

Because the charcoal could absorb the moisture from the air, becoming useless, only remove the cap from your filter when you need it. Replace your activated charcoal with each use. Cover your nose and mouth with a t-shirt if you have no other protection. A t-shirt can actually protect you from large particles, like dust or tear gas, though not perfectly. Try to create as perfect a seal as possible using both hands to keep the shirt over your nose and mouth. Bandanas, towels, and blankets will provide similar protection in an emergency. A simple piece of fabric can save your life against ash and dust from a volcanic explosion. Call poison control immediately. WIKI LINK If you or someone you know feels light-headed, nauseous, or experiences seizures or loss of consciousness after inhaling a chemical, make a note of the chemical and call poison control immediately. In America, poison control can be reached at the number 999. Move immediately to fresh air.