I can see several possibilities:
* Air pollution makes it harder to breathe, which makes it harder to think clearly and solve problems.
* Poor air quality would likely make the hindbrain anxious about survival, which would make it more reactive to other threats, and it can outright hijack the thinking brain -- which is possibly impaired by poor air quality and thus less able to resist.
* The change in air composition might directly alter biochemistry, such as making more stress chemicals or undermining the production of brain chemicals needed for logic and equanimity.
* A subset of particulate pollution comes from wildfire smoke. In this instance, people already facing an existential threat from fire might might be primed for survival response rather than rational response to further threats.
* My friends in Alaska tell me that they just get used to smelling smoke all the time in fire season, and stop responding to it. If habituation to danger signals is wider, however, people might be failing to react to threats at a distance or low levels, and wind up stuck with violence as their last option when they suddenly become aware of a serious threat at short range.
It would be interesting to explore the exact mechanism, but I doubt that would help solve the problem. Trying to find ways of providing cleaner air would be good, but we already knew that and haven't exactly done a stellar job of pursuing it.