I recently got an air quality monitor because I was worried about CO2 levels in my apartment having the windows closed and AC running all day every day. It turns out the levels were higher than I'd like (nearly 2000 PPM) and just cracking a few windows open very slightly, less than an inch, is enough to reduce the concentration to between 400 (outside air) and 900 depending on how many people are home. The window AC unit was still able to handle cooling the apartment with a relatively small change in usage.
I also run an air filter constantly so my PM2.5 and PM10 levels were already near-zero, but I'd imagine cracking a window helps with that.