Air Pollution, Neighborhood Socioeconomic Factors, and Neural Tube Defects in the San Joaquin Valley of California. 

Paediatr Perinat Epidemiol. 2015 Nov;29(6):536-45. doi: 10.1111/ppe.12244
Padula AM, Yang W, Carmichael SL, Tager IB, Lurmann F, Hammond SK, Shaw GM.