Our study will provide new evidence of the impacts of air pollution on neonatal and early childhood development for infants and children living in Puerto Rico and of factors that affect susceptibility to air pollution’s harmful impacts. We will do so by leveraging the success of PROTECT, our cohort study of 1800 pregnant women in Puerto Rico for whom a rich dataset of environmental, health, social, demographic, and behavioral factors are being collected. To these data, we will add measurements of air pollution exposures, early childhood development, and non-nutritive suck (NNS), a measure of newborn central nervous system function that has not yet been used to assess neonatal development in environmental epidemiology. We will use these data to achieve three aims: to (1) assess the association of air pollution on adverse birth outcomes; (2) determine the impact of air pollution on child development; and (3) examine effect modification of the air pollution-adverse health relationship by social and personal factors, including socio-economic status, maternal stress, birth outcomes, other pollutant exposures, and housing characteristics. 2) Experimental Approach: We will obtain air pollution exposure and health measurements for a cohort of 600 children living in Puerto Rico, whom we will follow from gestation through age four. We will do so using numerous measures of adverse birth outcomes and development, including preterm birth, annual respiratory and neurodevelopmental evaluations, and NNS. We will link these health measures to measurements of air pollution exposures, metal biomarkers, in utero exposures to contaminants of emerging concern (CECs), and maternal and child characteristics for each child. We will use multiple logistic regression, multi-level mixed models, and cluster analysis techniques to assess the effects of air pollution on adverse birth and developmental outcomes and effect modification of these effects by socioeconomic factors, maternal stress, birth outcomes, CEC mixtures, and home characteristics. Primary analyses will be performed for particulate pollution, with secondary analyses examining impacts of ozone, NO2, PM2.5 sources, air pollutant mixtures, and exposure biomarkers. All models will control for confounders. 3) Expected Results: We will provide evidence of air pollution-mediated risks of developmental delays and adverse birth outcomes for infants and children living in Puerto Rico, who are highly exposed to environmental pollution yet understudied. The insights gained from our research will inform strategies to reduce the frequency of adverse birth outcomes and developmental delays and to improve the cognitive and respiratory health of Puerto Rican children. In so doing, our Project will advance understanding of (1) the impact of air pollution exposures on the developing brain, a susceptible organ that is difficult to access in clinical evaluations, (2) how air pollution exposures and birth outcomes impact neurocognitive development of Puerto Rican children, and (3) the ability of personal factors and chemical mixtures to modify the impact of air pollution on development. ExpandCollapse Abstract