Living near freeways has been scientifically linked to cognitive impairments in young children and increases in autism. A small sample of the studies:
The rate of progression of hardening of the arteries, the cause of strokes, heart attacks and generalized aging, is double for those living within 100 meters of a freeway.
Künzli N, Jerrett M, Garcia-Esteban R, Basagaña X, Beckermann B, et al. (2010) Ambient Air Pollution and the Progression of Atherosclerosis in Adults. PLoS ONE 5(2): e9096. doi:10.1371/ journal.pone.0009096
Children who live within 500 meters of a major highway are not only more likely to develop asthma and other respiratory diseases, but their lung development may also be stunted permanently.
Gauderman WJ, et al. “Effect of exposure to traffic on lung development from 10 to 18 years of age: a cohort study,” The Lancet, Volume 368, February 2007.
Living within 1,000 ft of a freeway doubles the risk of a child being born with autism.
Volk HE, Hertz-Picciotto I, Delwiche L, Lurmann F, McConnell R. Residential proximity to freeways and autism in the CHARGE study. Environ Health Perspect. 2011 Jun;119(6):873-7. doi:10.1289/ehp.1002835. Epub 2010 Dec 13.
Children growing up with more traffic pollution have significantly lower IQs and impaired memory.
Suglia SF, et al. Association of Black Carbon with Cognition among Children in a Prospective Birth Cohort Study Am J Epidemiology 2008 167:280-286.
With young children myself, there is no way I would consider it.