Most of the modern home vacuum cleaners have pretty decent high efficiency particulate air (HEPA) filters in them nowadays. Assuming you still have power (a big if) you could seal a room to the best of your ability and leave your vacuum cleaners running (with the air intakes off the floor). If you have a bag type, remember to put a new bag in. Presto, filtered air, McGyver style. If all you have is an older style vacuum cleaner with no filter, then put a damp rag (and keep it damp) over the air intake, but be careful not to overheat the vacuum with too thick a cloth. The point of the water is that the majority of dust won’t fly when wet. If you want to be more creative, see if you can attach the air intake to a makeshift “bong” (or buy one from a “head” shop. Just ask a local teenager). This will pull the room air though a larger quantity of water. A standard bong would not do much as the bubble size would be too large and keep the majority of the air from contacting the water, but putting an aquarium bubbler at the submerged end of the bong stem will reduce bubble size and make it more effective. You could also think about adding a surfactant to the water to decrease surface tension making the bubbles smaller again. Perhaps some soap would work.
This would be the best option as it’s the tiniest particles that are the most damaging as they can pass through your lungs directly into your bloodstream and the kind of HEPA filters on vacuums won’t stop these. Of course if power goes out, then even a pricey safe room air filtration system would be useless if it wasn’t running on battery or backup. – SF in Hawaii
JWR Replies: Thanks for that suggestion. Some household vacuums use water pipe type filtration. One example is the Rainbow brand. This is the type of vacuum that we use on a day-to-day basis here at the Rawles Ranch. These Rainbow vacuums are quite expensive if purchased new, but can sometimes be found used at reasonable prices. (You might try a “Want to Buy” ad on craigslist.com.)
One advantage of the vacuum cleaner approach is that by sourcing outside air, it provides a positive overpressure for your shelter. This will make up for any minor inadequacies in tape sealing your windows and doors. Keep in mind that in a nuke scenario (nuclear bomb, a sub-critical “dirty bomb”, or a nuclear power plant melt-down) that your filter media will gradually become occluded with fallout dust and that dust will be very “hot.” This means that the filter must be isolated with shielding from the occupied portion of your shelter. (A double thickness stack of ammo cans filled with ammunition should be adequate for this task.) A variation of the vacuum cleaner approach that requires no elctricity is a hank crank-powered or bicycle frame-powered squirrel cage fan. These fans can be salvaged from discarded house furnaces. Just ask your local heating contractors for a couple of discards. Your local welding shop can improvise a sprocket attachment for powering the fan. For general information on shelter air supply and filtration systems, see Cresson Kearney’s indispensable book “Nuclear War Survival Skills“. (Available for free download at the Oregon Institute of Science and Medicine web site.)