"Leaf blower motors are inordinately large emitters of CO, NOx, HC, and PM according to a study conducted for the ARB (5). Two-stroke engine fuel is a gasoline-oil mixture, thus especially toxic. Particles from combustion are virtually all smaller than PM2.5. According to the Lung Association, a leaf blower causes as much smog as 17 cars."

Yeah, it's things like that that make me wish we could just outright ban all two-stroke engines. See also those gas scooters that occasionally go by - it's incredible how much stink they produce (and conversely, how incredibly clean-burning cars are now). At least there aren't too many of them.