[MengerSponge]

If you live on a main road, there's likely a lot of pollution in the air. How much is actually in your home will depend on a lot of complicated things (prevailing winds, home construction, etc), so it's best and easiest to just measure.

HN's own https://news.ycombinator.com/user?id=ahaucnx has a company with a DIY version: https://news.ycombinator.com/item?id=27124671

I got a Dylos before I learned about AirGradient, and I really like it too. Depending on your budget and tech savviness, it's a great option too.

One important note: these detectors don't do chemistry, and not everything that causes a spike of PM is actually a problem. Showering, for example, will cause a spike for hours, but those salts are probably fine. Running the oven will also cause a spike, and those particles probably aren't fine.