The main problem I see with this study is that it could be confounded by the fact that high air pollution areas have other problems too that could be causing the bad behaviour instead, like overcrowding, noise, frustration at slow traffic, etc.
Slow traffic would increase pollution. Noise could be an interesting one, I'm not sure whether there are statistics that measure noise pollution over a country, and how would noise pollution be coincident with air pollution? Overpopulation wouldn't count as they are measuring the same areas with the same population. Daytime population could be an issue (e.g. weekends vs weekdays) but I can't access the study.
The fact air pollution, in many cases, directly correlates with population density, make the results seem less surprising. It would be more interesting if less populated areas with high air pollution (perhaps near industrial plants, etc.) had a high correlation to violent crime rates in conjunction with highly dense populated areas.
Just in case anyone ever needs come correlation resources :).
Second, violence decreased in a given state 15 years after that particular state banned leaded gasoline. And it decreased for the particular cohort that had grown up without leaded gasoline but not particularly otherwise.
At a certain point you're left saying something like "Every time I point this gun at someone and pull the trigger they get struck by a bullet but this could be a spurious correlation!"
Lead fucks people up. Always has, always will. Pretty easy to trace a relationship between lead concentrations and societal disfunction.
This paper specifically looks at short term air pollution effect (ie, the kinds that will measurably rise and fall in different parts of a city over an 8-year span). Lead takes so long to affect a single person (since it mostly harms brain development in children, but crimes are mostly not committed by children) that it almost certainly being meaningfully measured here.
But, it being a short term study doesn't change much. A temporary increase in pollutants will serve to exacerbate underlying conditions. Supposing areas which experience the largest increase in the short term were also susceptible to higher levels historical, and most impacted by previous short term increases and we're back where we started.
EDIT: And the link between cities and higher crime seems to be well known and well studied. Here's what a quick google turns up: https://www.jstor.org/stable/10.1086/250109?seq=1#metadata_i...
So yes the incidence of cancer was higher in that area, but as soon as you controlled for population density, that effect disappeared.
Stuck with me as the 'most dangerous place' was a group of flats near the house I lived in at that time. I guessed it might be due to population density and was relived to find that was the case some time later.
Read the study before instantly dismissing it, maybe.
I think it would be very hard to isolate these factors into a "clean" study.
I'd wager the ones with the pollution are going to eat each other's faces at a much higher rate than those without.
For giggles and to test some fall of Rome hypotheses, run a 3rd cage where the water comes through lead pipes.
In any case, I agree you can't do this properly with humans. And lead is definitely a factor in many deceases including mental ones so it could well be one of the causes of increased violence.
Even within a single area of study "bad days" could involve activities correlated to increased pollution in many different ways.
An example that I can think of offhand: I'm way more stressed on days that neighbors are using powered yard tools (mostly mowers and blowers), which invariably also throw up lots of stuff my body and/or mind react negatively too (never been tested, but I'd be amazed if I didn't have at least an intolerance).
If a modern research paper cited by the Economist has failed to even account for some of the potential confounding here, then I have great concerns for the future of science.
This doesn't mean the future of science is in jeopardy. It just means more study is required and jumping to alter policy or make decisions based upon these studies, well, requires further study! :P