[Fitzcarraldo]

Burned plant material? how can that be harmful?

[Tijeras_Slim]

Abrasive ash, plus burned trees can increase the amount of radon in the atmosphere.

[GOPrincess]

I'm assuming that when the plant material burns, it becomes carcinogenic soot/smoke with particulates. (I should add a disclaimer that I am not a scientist or environmentalist, nor am I speaking for the AQMD, merely reporting on what they say, as that aspect of the fire story may be of interest/concern to some.)

[null and void]

Burned plant material? how can that be harmful?

Besides all the "natural" irritants and combustion products, decades of air polutants are 'sorbed by the plants, lead, sulfur, a witches brew of smokestack emissions, and God knowns what else are being dumped back into the atmosphere in a few days.