No doubt pollution will make you sick, but I'm inclined to think that depression has a lot to do with just living in an over-crowded, unattractive, big industrial city environment, having little contact with the natural world.
https://www.cdc.gov/ruralhealth/Suicide.html
Why imagine what is true when you can take a second and find out what is true? The truth is external to you, look for it. I don't want to be a jerk, but you have generated a hypothesis(great), why not test it against the facts available to you? Maybe you owe it to yourself.
According to this, it is also true of Germany:
https://ij-healthgeographics.biomedcentral.com/articles/10.1...
Let me know if you have better data. (I am aware that Indian Reservation tilt the scales big time toward rural areas, but do not think that removing them as outliers changes the balance)
I wish it took only a second to find out what is true, but data is complicated and has lots of confounding variables, and it's too easy to not account for them and get totally untrue information out of the data.
The algorithm to pursue truth:
1. Find out how you personally differ from happy and healthy people.
2. Reduce those differences however you can.
3. Watch yourself become happier and healthier.
4. That's the whole thing.
Don't demand that information conform to your assumption before you can take action. Take action and document your assumptions and challenge them along your journey to improvement.
A neural network does not make demands of its data set. It changes itself to better match the limited truth that it does see.
Uncertainty and doubt are your enemies. Challenge them with data don't reduce yourself to paralysis. Look up "Epistemic learned helplessness".
An example: Will flossing improve my health? Be the kind of person that wants to improve their health and tries to improve their health. Try flossing as matter of character, not based on whether it does independent of the social class of other flossers. If successful people think that other successful people floss, then they will too. There is no isolation among the variables. Don't demand that of reality.
The same could be said for : 'Working night shifts long term is linked to depression and suicide'
Now, while you can reduce global warming and air polution, its different to try and say we need to all work only during the day.
"Our teeth spent millions of years evolving in nature, makes sense that scrubbing them with unnatural mint-flavored pastes and plastic bristles would make them go haywire"
"Our eyes spent millions of years evolving in nature, makes sense that covering them with unnatural lenses would make them go haywire"
etc.
Cause and effect isn't necessary to reduce harm. You with me? It's nice to have certainly, but it is not required.
Imagine that I am a friend of yours. I tell you that my child is depressed and the doctor suggests pill1, it makes my child more lethargic. We try pill2 and the depression is gone.
I tell you that I am happy with the results of pill2 and that while I am interested in how it works and potential long-term consequences, I'm happy staying on pill2.
Is this imagined parent strictly better than a parent that refuses to try any pill until convinced of its mechanism and success? I would say yes.
Observation is the workhorse of the scientific paradigm, not idealized experimentation. The quantity, and thus value, of Inductive evidence is greater than that of Deductive evidence.
Which would you value in your medical care professional?
Measure what you value and optimize for it. Why do this devils advocate stuff?
As if there aren't uncountable other variables that have changed dramatically over millions of years. Or hell, do you even know if suicide rates are higher today than they were millions of years ago? No. You came here to try to suggest city living was inferior to rural living, and used "millions of years of evolution", and some implication that modern rural life is somehow more similar to those millions of years than urban life.
Then what does this suggest? Why does "unnatural light" (ignoring that humans have built "unnatural light" fires for ~1.7 million years) make a brain go haywire, but not, say, clipping one's toenails? Or reading books, or sitting on chairs, or being blasted by radio waves, or running on treadmills, or traveling over 15mph, or wearing clothes, or flying in airplanes, etc. What are you saying?
Health effects of radio waves: https://www.fcc.gov/engineering-technology/electromagnetic-c...
Artificial light exposure and circadian rhythm: https://www.ncbi.nlm.nih.gov/pubmed/30311830
I'm saying exactly what I said - there are some aspects of an urban technological life that are harmful to the human body
Edit: I guess I'm being pedantic at this point. My personal position is industrial agriculture is failing rapidly and that the modern world will reconcile with the fact that either we will all starve, or learn how to farm again. I spend half the year working on an organic farm, and my life is immeasurably better than when I'm in the city (which is of course, only my personal subjective datum which and I realize how much HN hates anecdote as evidence)