In the USA, “inner-city” is where the “slums” are, but in many places around the world, it’s the opposite. For example, France is famous for having undesirable suburbs and safer/cleaner/richer “inner city.”

The crime levels in metropolitan areas can vary significantly by the neighbourhood though, and some cities have very low levels of crime.

I’m not suggesting pollution doesn’t have any correlation to crime (it probably does) but it doesn’t seem to be one of the more significant factors if you wanted to try to explain why some neighbours / populations commit more crime.

But air pollution's impact on cognition is a well-studied topic. See e.g: https://www.pnas.org/content/115/37/9193, https://www.sciencedirect.com/science/article/pii/S019701862..., and especially https://jech.bmj.com/content/64/3/223.short: "Although results were not statistically significant, the associations found between exposure to NO2 and cognitive functions suggest that traffic-related air pollution may have an adverse effect on neurodevelopment, especially early in life, even at low exposure levels." In other words, air pollution makes you dumb and being male and dumb makes you more prone to commit crime. I find no reason not to believe that this may be a significant factor.

It's not racist to point out higher amount of crime among many migrant populations. Often such populations are poorer and less educated than general population, both of which are attributes that correlate with higher crime rate, and also ones mostly determined by your parents wealth rather than your own actions.

I didn't say it was racist and it is not necessarily racist. Just as it isn't racist to point out the higher amount of crime among many young male populations. Often such populations are poorer and less educated than general population, both of which are attributes that correlate with higher crime rate.