going into mountain caves is a good idea but can be quite risky...don`t go too deep without any carbon monoxyde monitor..better to have a multi-gas-monitor in hand...there are different gases (no smell) that can await someone seeking shelter in a cave...these gases can knock someone out (kill) before he can react.
a air filter in a shelter should be one using active charcoal filters..the air pump will require electric power..manual power generators would be best in case of power outage.
shelters are not submarines.(not even airtight fallout shelters)..should a shelter get submerged, then it gets interesting...how long can one live on the remaining air..(very difficult calculation) (not long) in the worst case, the shelter gets flooded and there might just be a small air bubble left..then what? having pure medical oxygen bottles ready might help a bit but the buildup of carbon dioxide will lead to asphyxation. so how long will one be able to breathe pure medical oxygen?.or rather: how much oxygen does the presurized bottle hold?
it seems that fully ready scuba diving equipment should be kept at all times..it buys some time to find a way out while being more or less mobile/flexible..
should circumstances other than flooding prevent air supply from outside, then the best thing is:
CARBON DIOXIDE SCRUBBING! which is not easy..there are lots of sites that tell you how to make your own carbon dioxide scrubbing mixture..but the "chemicals" needed have to be handled with great care and risk of wrong dosage or accident in a stress situation is very high..there is some info on how to make your own "rebreather" , where you keep breathing your recycled breath after it went through a carbon dioxide scrubber..again here it is quite a complicated task to get it right in a stress situation...and those rebreathers usually don`t make it long...
there are different methods to take out carbon dioxide from the air but most are quite complex ...and don`t think that a few plants will do it...they need lots of light for that..otherwise they add to the co2 buildup. (don`t forget to have a co2 monitor as well)
during operation summer pulse 04, the us navy had submarine emergency exercises going on, using a new and very simple kind of carbon dioxide scrubber that looks like a white cloth/sheet, which can be taken out of a box and be hanged like a towel for drying on a rope..it does the carbon dioxide scrubbing very well and is almost failsafe and easy to handle....
a couple of years ago i inquired about those scrubbers and found that a metal box with lots of sheets and unlimited shelf life cost nearly 600usd. a cheaper version (non metal box) with only limited shelf life was around 400 usd ....
too expensive! so i did not buy any ... and unfortunately i can`t remember the producing company`s name..i got the paper somewhere and i`ll look for it should anybody be interested...or maybe someone else already knows which company it is and could let me know, before i turn my house inside out....
