Utah’s low-smoking population and high population density concentrated in mountain valleys, with intermittent industrial activity and frequent temperature inversions, have yielded unique opportunities to study air pollution. These studies have contributed to the understanding of the human health impacts of air pollution. The populated mountain valleys of Utah experience considerable variability in concentrations of ambient air pollution because of local emission sources that change over time and episodic atmospheric conditions that result in elevated concentrations of air pollution. Evidence from Utah studies indicates that air pollution, especially combustion-related fine particulate matter air pollution and ozone, contributes to various adverse health outcomes, including respiratory and cardiovascular morbidity and mortality and increased risk of lung cancer. The evidence suggests that air pollution may also contribute to risk of pre-term birth, pregnancy loss, school absences, and other adverse health outcomes.