 How to make a gas mask? Whether you are want to defend yourself from the apocalypse or against a round of police-tier 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. Making a gas mask. Know the difference between gas and particle contamination. Tier 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, tier gas, and dust are all particle contaminates. Cut the bottom off of a transparent 2-liter soda bottle. Using a razor blade, cut the bottom inch off of a large bottle and discard the bottom. Cut a U-shaped opening for your head. Use a marker to draw a, U, across the front of the bottle, capped side down. This needs to fit snugly 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 snugly 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. Cut them near the bottom, as you will need them later to attach the mask to your face. Staple the elastic bands to your mask. Attach the elastic bands near eye level so you can securely keep the mask on your face without your hands. 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 it to your face, making sure there are no holes in the insulation that would allow contaminated air to your face. Make sure the bottle cap is off, and breath in the clean air.