According to researchers in the U.S., breathing air that is heavily contaminated with traffic pollution may be associated with reduced memory, learning ability and I.Q. in children.

In a study reported in the American Journal of Epidemiology, 202 children aged 8 to 11 years were subjected to several tests, including those for vocabulary, I.Q., memory and learning. Those children who were exposed to the heaviest traffic pollution (as indicated by levels of black carbon, a marker for traffic pollution) returned the lowest test scores.

 
The researchers suggested that the observed effects may be due to black carbon causing inflammation and oxidative damage in the nervous system, but stated that more work needed to be done in this area.

 
In light of these findings, it may be preferable to live in areas with minimum traffic pollution. Where polluted air cannot be avoided, it may be best to stay indoors, with windows closed, during the heaviest traffic times and limit outdoor activities and window opening to those times when traffic activity is at it’s lowest  levels.

 
Reference

Suglia, S., Gryparis, A., Wright, R.O., Schwartz, J. and Wright, R.J.  2007  Association of black carbon with cognition among children in a prospective birth cohort study   American Journal of Epidemiology 167(3) : 280-286.  Online, available at : http://aje.oxfordjournals.org  (viewed on 6.3.08)