Are you considering purchasing a gas mask, called a promask (short for Protective Mask) by professionals, as part of your survival preparations? It may be more useful than you imagined.
For what they cost, they are an effective tool required to deal with a spectrum of threats that would otherwise be difficult to address without one. Most people weigh the decision from the context of some kind of extreme terrorist nerve gas attack, or similar event, which is realistically one of the least likely occurrences. However, if you live in a [sub]urban environment, or near any major shipping/transportation arteries (e.g. rivers, railroad tracks, highways), you could be aided by a Protective Mask (ProMask) to combat threats such as riot control agents, hazardous chemical spills, wildfire smoke, or other toxic or irritating agents.
If you've ever watched the Bio channel's show "I Survived...", they have had a number of episodes that demonstrate clear cases, not related to the worst-case uses, where a promask would have greatly and positively influenced the timeline of events. Here is one example, when a train full of chlorine gas derailed nearby: http://www.biography.com/tv/i-survived/episodes/06-wayne-maryhollylinda
I recommend the Scott M98 CBRN promask (formerly NBC "Promask 40"). It has several excellent features:
- Full-view polycarbonate visor, not individual eye lenses
- Is available in both a Medium/Large size (full size adults, most males) and S size (smaller adults, women, teenagers)
- Uses NATO-standard 40mm threaded canisters, which are likely to be used by professional first responders and military personnel
- Can attach the canister to either side, which also aids in weapons sighting, or use two simultaneously, for less breathing resistance
- Has a voice modulator assembly, to aid verbal communications
- Is available with an (optional) drinking tube
- Costs around $125.
I would also recommend a quality carrier, to protect your mask, and keep in handy in the event of an imminent emergency. The Blackhawk Omega Elite gas mask carrier has both a shoulder strap and belt/thigh straps, and costs about $65.
For the contextually low price, and range of flexible capabilities that a pro mask offers, I find it a wise addition to any serious preparedness load-out.
NOTE: CBRN (Chemical, Biological, Radiological, Nuclear) is a modernized standard of the previous generation NBC (Nuclear, Biological, Chemical) terminology and certifications.