Residential particulate matter, proximity to major roads, traffic density and traffic volume as risk factors for preterm birth in California

BACKGROUND While pollution from vehicle sources is an established risk factor for preterm birth, it is unclear whether distance of residence to the nearest major road or related measures like major road density represent useful measures for characterising risk. OBJECTIVE To determine whether major road proximity measures (including distance to major road, major road density and traffic volume) are more useful risk factors for preterm birth than other established vehicle-related measures (including particulate matter