Air pollution has been linked to lower birth weights in babies . In a recent study , out of 182 babies born to mothers exposed to high doses of ash and soot during the World Trade Center attack of 2001 , 15 were classified as having low weight . Of 2300 babies born in the same time period in another hospital in NY , 92 were classified as having low weight . Is there evidence to suggest that the exposed mothers had a higher incidence of low - weight babies ?