Radioactive Fallout

[NorthernRaider]

No its not unrealistic at all, theres literally hundreds of designs for simple filters that can be made easily to with give you even just 1 atmosphere overpressure in your safe room, time to get books like I listed or do a google. Rockey Mountain SG used to have a massive archive of stuff and their was an entire section on filtration systems.

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A water shower over the house , a fine falling mist can really reduce the amount of fallout settling on your home and these can be made fromn bits of DIY plumbing kits and somethimes if you dont have good water pressure a few large water butts connected to your house system, plus a battery powered pump to spray your roof every hour or so for a few minutes.