||A spatial and temporal exploratory investigation of ambient air pollution, as measured by PM2.5 (fine particulate matter of size 2.5μg/m3), and cumulative (i.e., entire pregnancy) and timing-specific (trimesters) exposure to PM2.5 during gestation and the risk of preterm birth (PTB) among Utah women who gave birth between 2005 and 2008 was performed as a master's thesis research project. The CDC's (Centers for Disease Control) HBM (hierarchical Bayesian space time modeling system) data were used to interpolate daily PM2.5 concentrations for Utah census tracts from 2001-2008. Interquartile ranges were then used to create exposure level categories. Birth certificate data that were subsequently surveyed (i.e., PRAMS data) were spatially associated with census tracts and represented births occurring in Utah during 2005-2008. Exposures to PM2.5 were modeled using logistic regression (binomial generalized mixed effects linear modeling) and odds ratios with confidence intervals. PTB was designated as the response variable and census tracts (n=488) were chosen for the random effect. Our analyses revealed that births occurring in the winter months (December, January, or February) had higher odds of PTB (just over 13% higher, CI 1.03 - 1.25). Additionally, our exploratory investigations indicated that Utah mothers (2005-2008) with the lowest levels of educational attainment experienced the highest exposures to PM2.5 during the entire pregnancy and within each trimester. We found no significant relationship between cumulative or timing-specific exposures to fine particulate matter and PTB among Utah women; however, other social and risk factors, like education level and attending prenatal care visits, remain an important priority for targeted intervention and reduction of PTBs among Utah women.