[tomatsu]

Devices for measuring the concentration of particulates (PM10, PM2.5, and maybe PM1.0), TVOC (total volatile organic compounds), and HCHO (formaldehyde) are fairly affordable nowadays. You could get one of those.

The air quality indoors is usually even worse than the air outside if you aren't using some filtration system. New-ish buildings release formaldehyde, laser printers release particulates and ozone, 3d printers release VOCs and particulates, and there is lots of dust generated by inhabitants and their pets.

Sadly, the Trump administration did a rollback of emission and fuel efficiency standards. It's a big step in the wrong direction.

Personally, I'd even ban combustion engines within city limits. It's completely insane that we poison the air we breathe 24/7.