Ambient PM exposure and tuberculosis reactivation: a cross-sectional study in an intermediate burden city.

Hong Kong is an intermediate tuberculosis (TB) endemicity city dominated by reactivation diseases. A cross-sectional study on the clinical and epidemiologic data of newly diagnosed TB cases was conducted in such a setting, to examine the association between ambient PM and TB reactivation. After the exclusion of cases most likely resulting from recent infection, four distinct TB population phenotypes were delineated by latent class analysis based on their reactivation risk and clinical profiles ( = 2,153): '' (26%), '' (34%), '' (19%) and '' (21%). Overall, exposure to high concentrations of ambient PM 6 and 12 months before the notification was significantly associated with '' membership (OR = 1.07 and 1.11, respectively) compared with ''. Such association was less evident for other phenotypes. The differential pattern of association between ambient PM exposure and TB population phenotypes suggested the role of ambient PM in TB reactivation.