The primary data for this project will come from a grant funded by the National Institute of Environmental Health Sciences (R21 ES 014891-01A1, “Influences of genetics and air pollution exposures on birth outcomes”). Part A of that grant uses refined air pollution and traffic density data to examine their influence of on adverse birth outcomes such as low birth weight and premature birth. Part B of that grant evaluates the feasibility of assembling a birth-cohort to provide saliva samples for the analysis of genetic and epigenetic susceptibility to the effects of air pollution. For the project funded by the present grant, additional exposure data from the prenatal periods of over 300,000 births in the San Joaquin Valley of California will be obtained, and novel statistical methods to evaluate possible longitudinal and joint effects of pollutant mixtures on birth outcomes will be used. In addition to the air pollution data, detailed traffic counts and density data, census and neighborhood-level characteristics, and some simulated individual-level data will be used to control for confounding and identification of susceptible subgroups. Genetic samples will be obtained from mothers and children identified in Part B of the previous grant (R21 ES 014891-01A1) and stored for future analysis. Extensive investigations will be conducted to identify the proper set of genetic polymorphisms that may influence susceptibility to the effects of air pollution and those that are associated with preterm birth. These novel methods may be used to examine air pollution's influence on major childhood health conditions such as cancer, asthma, autism, and obesity.