I was using that as an example, there are other times when these air inversion can cause nasty air pollution to build up. I'm as libertarian as the next guy, but air pollution doesn't respect property lines.
From Wikipedia about the Donora Smog (your link):
The pollutants in the air mixed with fog to form a thick, yellowish, acrid smog that hung over Donora for five days. The sulfuric acid, nitrogen dioxide, fluorine, and other poisonous gases that usually dispersed into the atmosphere were caught in the inversion and accumulated until rain ended the weather pattern
H
2SO
4, NO
2, and F
2 are not typical components of wood smoke.
Temperature inversions typically trap air in valleys (which is what happened at Donora). You have to have the right topography and weather conditions to trap pollutants, and you have to have a high enough population density for the pollutants to reach harmful concentrations.
Without the industrial sources, likely Donora and the residents would have been fine.
When you have one person per square mile, or even a dozen heating separate residences with wood, that smoke isn't generally going to cause any problems, even if it is trapped by an thermal inversion. You have to have a valley to trap the air in, and that is a fairly rare situation here in North Dakota. Despite having an average of 10 people per square mile here, most rural homes could be heated with wood or coal with no deleterious effects on the environment.