This study is to examine the effects of PM2.5 on innate and adaptive antimycobacterial (anti-Mycobacterium tuberculosis, M.tb) immune mechanisms in primary bronchoalveolar cells from M.tb-exposed and unexposed human subjects. The goal is to assess the effects of urban air pollution on human antimicrobial immunity against communicable respiratory diseases. Given the wide geographical scales for both air pollution and Mycobacterium tuberculosis infections, new knowledge to be gained from this project will have significant global health implications.