We're down here in Southeast PA, and the wildfire smoke went from "huh, that's odd" to "what the frrp?" so quickly.

I have to admit that it caught me a little off guard; a massive blanket of smoke that lasted days was not really on my list of preps.

As a firefighter, they've beaten into my head the danger of the fine particulates that come with smoke, so I took the fact that when I got home from work, the particulate levels at my house were 462 on a scale that only went to 500 seriously.

The perma-stash of N95's were really useful, I was out weeding the garden while masked, but I felt bad for my cats. They hate wearing N95's.

The smoke was seeping into the house, and I was able to build a relatively high-volume faux-HEPA air filter from a box fan, cardboard and a furnace filter, it worked quite well, but it was ugly.

I guess you're getting the smoke from north of the border. Nasty.

We've been dealing with our own nasty fires and smoke out West. The combination of drought and sustained winds are playing hell out here. I'm safe -ish where I am, but 2 hours west there are new evacuation orders just issued.

Good call on the N95s. I know people here (guys, naturally) who "toughed it out" when the air quality was 10+, the worst rating, off the scale. They were physically ill the next day; that fine particulate chemical soup goes straight into the bloodstream.

BTW, lots of people report that box fan filters are highly effective, as long as you use 2-3 high quality furnace filters arranged in a box and taped up using cardboard in the gaps. This gives adequate airflow, whereas a single filter over the fan does not.

Try a web search on "Corsi-Rosenthal box" about making an air cleaner from furnace filters and fans. I have figured it is ok if there are leaks around the edges of the filters, since air circulates through the fan multiple times and gets cleaned further with each pass, but I haven't done any testing with particle counters or anything like that. I do know that the single filter cleaner I made a few years ago helped at that time.

Furnace filters are designed to work on the intake / vaccum side of the furnace fan. All the successful improvised designs I've seen place the filters on the intake side of the box fan; multiple filters arranged as a box there increase the airflow greatly.

Years ago I tried something similar on the exhaust / pressure side of a fan. Total fail.

Did you really get the masks on the cats? I think that was a joke. But protecting your pets in an emergency like this isn't a joke. The only viable way seems to be keeping them in a small, air-filtered space.

Lifehacker just had an article.

https://lifehacker.com/this-cheap-diy-air-purifier-actually-works-1850520488

No, I did not get the masks on the cats

But I did keep them inside, and they were super-grumpy about it.

Martin.... it worked quite well, but it was ugly. I feel this goes to the old 'If it's stupid and it works....it isn't stupid.' As long as its effective.

Also....I had a great laugh at the thought of you TRYING to N95 a CAT!!!! Thanks.