Effects of Particulate Air Pollution on Tuberculosis Development Methodological Consideration of Long-term Exposure and Time Lag.

Objectives Epidemiologic evidence for associations between ambient particulate matter (PM) and tuberculosis (TB) risk is accumulating. Two previous studies in South Korea found the association between air pollution and TB, particularly for SO2. In this study, we conducted an annual time-series cross-sectional study to assess the effect of PM10 on TB risk in seven major cities of South Korea from 2010 to 2016, taking into account the time lag and long-term cumulative exposure. Methods Age-standardized TB notification rates were identified using the Korea National TB Surveillance System. Annual averages of PM10 concentrations were obtained from annual Korean air quality reports. We applied a generalized linear mixed model with unconstrained distributed lags of exposure. We adjusted for potential confounders such as age, health behaviors and area-level characteristics. Results We found that annual PM10 averages decreased over time and age-standardized TB notification rates also decreased over time. The association between cumulative exposure to PM10 and TB incidence increased as longer exposure duration was considered. One standard deviation increase (5.63 ㎍/m3) of PM10 for six years was associated with 1.197 (95% CI: 1.171, 1.225) times higher TB notification rate. The marginal association of exposure duration with TB notification rate was highest at four and five year prior to TB notification. This association remained consistent even after exposure to SO2 was adjusted for. Conclusion The finding of this study suggests that the effect of cumulative exposure to PM on TB risk may exist and its lag effect may also exist.