Inhalation of PM2.5 particles have been linked to numerous health problems in the long-term. Such problems include heart and respiratory disease, increased chances of stroke and lung cancer… even decreased general lifespan! (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740125/ , https://ww2.arb.ca.gov/resources/inhalable-particulate-matter-and-health) These especially impact you if you are currently suffering from/have a history of heart or respiratory conditions.
If you’re not sure what are PM2.5 particles, TLDR; they are extremely small pollutant particles (10 micrometers to 2.5 or even smaller) that, due to their small size, can penetrate directly into your bloodstream from your lungs. Also due to this small size, your lungs have trouble clearing these pollutants out.
Here are the sequential steps to take to protect yourself:
Get yourself an N95 mask IMMEDIATELY. If you have to go outside your home, ALWAYS wear this! These babies can filter out particles as small as 0.3 microns in size, so a good chunk of the pollutants (but NOT ALL) will be filtered away. (Update 2: If you are unable to get an N95, that is fine as long as you follow steps 2, 3, 4, 5, since these masks are for when you need to go outside. You do not have to wear an N95 in your home as long as you do the next steps)
Close all windows, doors and any openings leading to outside. Yes, your house will get stuffy. Yes, your house will get warm. But at least that beats getting a million health problems 5 years down the road. If you want, turn on your air-conditioning to combat the heat and stuffiness, but make sure that it doesn’t take in air from outside or that defeats the purpose of closing off your house.
Set up a regular schedule to mop your floors and wipe all surfaces. After a few hours, assuming you have closed your doors and windows, the floor might feel a little grimy, dusty, and/or sticky. Why it feels that way is due to the dust settling down on surfaces, and that’s great! That means the dust isn’t flying around in the air getting inhaled. Depending on how badly hit your area is, you might want to set up a schedule to wipe them up (e.g. twice a day if you are in a badly hit area, or once a day if your area isn’t that bad)
Get yourself good air purifiers that use HEPA filters. Make sure that the HEPA filter is the real deal, not “HEPA-like” or “Inspired by HEPA”.
Avoid going outside your home. This is assuming that you are far away from the actual wildfires themselves and are in no actual physical danger of getting burnt. The worst of the pollutants are on the streets. Never leave your house unless absolutely necessary! This means no “hanging out with friends in the pub” or “going to the beach” etc. If you absolutely HAVE to leave the house (e.g. grocery runs), limit that time to as short as possible. Do what you need to do, and get back home ASAP.
Essentially, these steps are to make a “safe air bubble” in your house. With air purifiers cleaning the air and you wiping up any particles that settle on surfaces, your home will definitely have cleaner air than outside.
If anyone has better tips, please post it below so that people can follow those to protect themselves and their families. If you want, you can read more about PM2.5 on the wiki as well: https://en.wikipedia.org/wiki/Particulates . Stay safe and take care of yourself everyone!
Update: Thank you so much u/Yung_Wizzerd for the award!
Update 2: If you do not have an N95 mask due to mask shortages, that means you have to take Steps 2,3,4,5 very strictly. The N95 mask is only used for leaving your house, as long as you limit that time to as short as possible, you should be good. Gotta make the best out of the worst situation!