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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 th

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.

numlock86 7y ago
That was my very first thought before I even read the article or clicked on HN comments ...
Frost1x 7y ago
Reminds me of one of the prototypical sociological study examples of correlation vs causation where something akin to icecream sales correlated highly with murder rates. 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.
- mnw21cam 7y ago
  I'm sure https://xkcd.com/1138/ https://xkcd.com/1138/ is relevant.
  - codeduck 7y ago
    It correlates.
    - close04 7y ago
      https://tylervigen.com/spurious-correlations https://tylervigen.com/spurious-correlations (or https://tylervigen.com/old-version.html https://tylervigen.com/old-version.html ). Just in case anyone ever needs come correlation resources :).
      - codeduck 7y ago
        I was being glib about the relevance of the xkcd :-)
      - magashna 7y ago
        Some of those are interesting just because I never assumed it happened or it was being tracked. And some of them are a surprising scale. 800 deaths from being tangled in bedsheets!
      - Symmetry 7y ago
        First, there's a plausible biological link between lead and violence. We can performed double-blind controlled experiments with mice and see it. 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!"
- huffmsa 7y ago
  Except it's not a case of ice cream and summer time. Lead fucks people up. Always has, always will. Pretty easy to trace a relationship between lead concentrations and societal disfunction. https://en.wikipedia.org/wiki/Lead%E2%80%93crime_hypothesis https://en.wikipedia.org/wiki/Lead%E2%80%93crime_hypothesis
  - Armisael16 7y ago
    The article specifically mentions the lead-crime hypothesis as a different example of hypothesized linkages between air pollution and crime. It seems exceptionally likely that it isn’t what they’re looking at. 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.
    - mirthflat83 7y ago
      Hacker news and not reading the article before commenting name a more classic combination
    - huffmsa 7y ago
      Of course I didn't read the article. I hear it's paywall, and I and the economist's paywall really don't get along. 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.
    - Symmetry 7y ago
      And we're currently in this weird situation where older criminals are more violent than younger criminals, in contravention of how things typically go, because older criminals were exposed to lead as children.
spangry 7y ago
You'd think it would be fairly easy to control for population density. However the study abstract indicates the only other confounding variable they controlled for was 'temperature'. 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_info_tab_contents https://www.jstor.org/stable/10.1086/250109?seq=1#metadata_i...
- ljf 7y ago
  Very interesting - I remember a study when I was at uni saying that mobile phone masts were linked to cancer rates. They also forgot that mobile phone masts were normally on top of very tall buildings and very tall buildings often house lots and lots of people. 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.
- hatmatrix 7y ago
  Since they were looking at increases in violence and air pollution on a daily interval, temperature was probably there to control for weather-related phenomena.
tyfon 7y ago
Or that low income areas with higher crime in general have less money to buy new and efficient/clean cars so the pollution rises. I think it would be very hard to isolate these factors into a "clean" study.
- huffmsa 7y ago
  You can't do it with humans, for ethical reasons, but why not take some other social animal, say mice, put one population in a box with zero pollution, and one hooked up to an old car exhaust with leaded gasoline? 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.
  - tyfon 7y ago
    Can one still buy leaded petrol in the states? 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.
    - opencl 7y ago
      It's still widely available (and in use) for small piston aircraft as avgas. And it seems like tetraethyl lead is still available for people to mix their own leaded gas to put in very old cars.
hatmatrix 7y ago
They were looking at daily fluctuations.
brightball 7y ago
I saw something years ago that shows a global correlation of violent crime with use of leaded gasoline in the country.
bart_spoon 7y ago
I can't read the article due to the the paywall, but any halfway decent study should be attempting to control for these things. Propensity score matching, or simply including these factors in a regression model should help remove some of the effects. Obviously, there is potentially an unlimited number of possible cofounders, and therefore the assumption that they've all been accounted for should always be met with skepticism, and is why the mantra "correlation is not causation" is so often repeated. 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.
- mondoshawan 7y ago
  There are many thousands of studies, just like this one, that imply correlation, but not causation and fail to properly account for confounding factors. Occam's razor implies this is more likely to be yet another study that fails to account for X of these factors. 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
chippy 7y ago
The study solved this problem by looking at changes in the same areas, not between areas. 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.
quantguy11959 7y ago
I agree consider Singapore, massive pollution problems but one of the safest countries in the world.
dannykwells 7y ago
They controlled for this!!! Read the study before instantly dismissing it, maybe.
mjevans 7y ago
I was thinking something similar. 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).

numlock86 7y ago

That was my very first thought before I even read the article or clicked on HN comments ...

Frost1x 7y ago

Reminds me of one of the prototypical sociological study examples of correlation vs causation where something akin to icecream sales correlated highly with murder rates. 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.

mnw21cam 7y ago
I'm sure https://xkcd.com/1138/ https://xkcd.com/1138/ is relevant.
- codeduck 7y ago
  It correlates.
  - close04 7y ago
    https://tylervigen.com/spurious-correlations https://tylervigen.com/spurious-correlations (or https://tylervigen.com/old-version.html https://tylervigen.com/old-version.html ). Just in case anyone ever needs come correlation resources :).
    - codeduck 7y ago
      I was being glib about the relevance of the xkcd :-)
    - magashna 7y ago
      Some of those are interesting just because I never assumed it happened or it was being tracked. And some of them are a surprising scale. 800 deaths from being tangled in bedsheets!
    - Symmetry 7y ago
      First, there's a plausible biological link between lead and violence. We can performed double-blind controlled experiments with mice and see it. 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!"
huffmsa 7y ago
Except it's not a case of ice cream and summer time. Lead fucks people up. Always has, always will. Pretty easy to trace a relationship between lead concentrations and societal disfunction. https://en.wikipedia.org/wiki/Lead%E2%80%93crime_hypothesis https://en.wikipedia.org/wiki/Lead%E2%80%93crime_hypothesis
- Armisael16 7y ago
  The article specifically mentions the lead-crime hypothesis as a different example of hypothesized linkages between air pollution and crime. It seems exceptionally likely that it isn’t what they’re looking at. 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.
  - mirthflat83 7y ago
    Hacker news and not reading the article before commenting name a more classic combination
  - huffmsa 7y ago
    Of course I didn't read the article. I hear it's paywall, and I and the economist's paywall really don't get along. 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.
  - Symmetry 7y ago
    And we're currently in this weird situation where older criminals are more violent than younger criminals, in contravention of how things typically go, because older criminals were exposed to lead as children.

spangry 7y ago

You'd think it would be fairly easy to control for population density. However the study abstract indicates the only other confounding variable they controlled for was 'temperature'. 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_info_tab_contents https://www.jstor.org/stable/10.1086/250109?seq=1#metadata_i...

ljf 7y ago
Very interesting - I remember a study when I was at uni saying that mobile phone masts were linked to cancer rates. They also forgot that mobile phone masts were normally on top of very tall buildings and very tall buildings often house lots and lots of people. 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.
hatmatrix 7y ago
Since they were looking at increases in violence and air pollution on a daily interval, temperature was probably there to control for weather-related phenomena.

tyfon 7y ago

Or that low income areas with higher crime in general have less money to buy new and efficient/clean cars so the pollution rises. I think it would be very hard to isolate these factors into a "clean" study.

huffmsa 7y ago
You can't do it with humans, for ethical reasons, but why not take some other social animal, say mice, put one population in a box with zero pollution, and one hooked up to an old car exhaust with leaded gasoline? 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.
- tyfon 7y ago
  Can one still buy leaded petrol in the states? 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.
  - opencl 7y ago
    It's still widely available (and in use) for small piston aircraft as avgas. And it seems like tetraethyl lead is still available for people to mix their own leaded gas to put in very old cars.

hatmatrix 7y ago

They were looking at daily fluctuations.

brightball 7y ago

I saw something years ago that shows a global correlation of violent crime with use of leaded gasoline in the country.

bart_spoon 7y ago

I can't read the article due to the the paywall, but any halfway decent study should be attempting to control for these things. Propensity score matching, or simply including these factors in a regression model should help remove some of the effects. Obviously, there is potentially an unlimited number of possible cofounders, and therefore the assumption that they've all been accounted for should always be met with skepticism, and is why the mantra "correlation is not causation" is so often repeated. 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.

mondoshawan 7y ago
There are many thousands of studies, just like this one, that imply correlation, but not causation and fail to properly account for confounding factors. Occam's razor implies this is more likely to be yet another study that fails to account for X of these factors. 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

chippy 7y ago

The study solved this problem by looking at changes in the same areas, not between areas. 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.

quantguy11959 7y ago

I agree consider Singapore, massive pollution problems but one of the safest countries in the world.

dannykwells 7y ago

They controlled for this!!! Read the study before instantly dismissing it, maybe.

mjevans 7y ago

I was thinking something similar. 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).