Even though I don't even smell it. These sensors are just incredibly sensitive.
Another example: burning one candle increases PM 2.5 considerably and after blowing it out the wick gives a little wisp of smoke that makes it peak from a normal 1 to 50 or so.
It's very enlightening. Even a single push of spray deodorant releases a crazy amount of particles and makes the purifier go crazy for a short while.
Just having an ultrasonic humidifier in the bedroom makes the PM25 counter jump from 1-2 to 200-250.
I would avoid using them unless, perhaps, I ran the output through a filter. Or I would use an evaporative humidifier instead.
"The case against ultrasonic humidifiers."
If you absolutely need more humidity in your home, get something like the Venta LW45 which has a half-submerged rotating disk and blows air over the still wet surface. Works with tap water (requires regular cleaning and a special additive).