The transition from a centrally planned socialist economy to free markets brought unprecedented economic growth to Mongolia, but also severe environmental problems associated with rapid urban development. Its capital city Ulaanbaatar has experienced extreme air pollution during the winter months for almost two decades. While the impacts of local air pollution on cardiovascular and respiratory health in Ulaanbaatar are well documented, this is the first study to evaluate the relationship between particulate matter concentrations and the subjective well-being of its residents. We match newly available survey data on subjective well-being in Ulaanbaatar with particulate matter readings and weather data and estimate a significant relationship between air pollution and self-reported life satisfaction. The estimated coefficients imply a potentially large willingness-to-pay for better air quality.