If you are a young adult, especially if you are pregnant, you should think twice when going to the city or at least being exposed to a lot of emission-spewing vehicles and industrial areas. As air pollutants enter women’s system, it reaches their unborn babies. As a consequence, the babies’ IQ level gets damaged. It was proven that the mothers of children whose IQ test results were lower were exposed to PAHs (polycyclic aromatic hydrocarbons), while the mothers of children whose IQ test results were higher were not as much exposed to PAHs. This often results in poor school performance and eventually damages higher-level learning, such as college years and job training.

In my opinion, despite longer commutes, if my job was in the city, I would personally take a longer commute from the suburbs or rural area to reduce my exposure to PAHs.

http://www.environmentalhealthnews.org/ehs/news/air-pollutants-and-childrens-iqs