Particulate matter is associated with sputum culture conversion in patients with culture-positive tuberculosis

Emerging risk factors for tuberculosis (TB) infection, such as air pollution, play a significant role at both the individual and population levels. However, the association between air pollution and TB remains unclear. The objective of this study was to examine the association between outdoor air pollution and sputum culture conversion in TB patients. In the present study, 389 subjects were recruited from a hospital in Taiwan from 2010 to 2012: 144 controls with non-TB-related pulmonary diseases with negative sputum cultures and 245 culture-positive TB subjects. We observed that a 1 μg/m(3) increase in particulate matter of ≤10 μm in aerodynamic diameter (PM(10)) resulted in 4% higher odds of TB (odds ratio =1.04, 95% confidence interval =1.01–1.08, P<0.05). The chest X-ray grading of TB subjects was correlated to 1 year levels of PM(10) (R(2)=0.94, P<0.05). However, there were no associations of pulmonary cavitation or treatment success rate with PM(10). In subjects with TB-positive cultures, annual exposure to ≥50 μg/m(3) PM(10) was associated with an increase in the time required for sputum culture conversion (hazard ratio =1.28, 95% confidence interval: 1.07–1.84, P<0.05). In conclusion, chronic exposure to ≥50 μg/m(3) PM(10) may prolong the sputum culture conversion of TB patients with sputum-positive cultures.