Infectious Disease
Ambient air pollution and tuberculosis incidence in Brazil: A nationwide panel regression study, 2003-2019 Thi Mui Pham* Thi Mui Pham Pham Pham Pham Pham Division of Epidemiology, University of Utah, UT, USA
Background: Ambient fine particulate matter (PM2.5) impairs pulmonary immune defenses and may accelerate progression from latent tuberculosis (TB) infection to active disease, yet population-level evidence remains limited.
Methods: We conducted a longitudinal panel analysis using national TB surveillance data from Brazil linked to wildfire-related PM2.5 concentrations across 5,530 municipalities from 2003–2019. Monthly TB notifications were analyzed using Poisson regression with fixed effects for municipalities, state-by-year, and state-by-month to control for time-invariant factors, state-level secular trends, and seasonality. Models adjusted for population size, meteorological conditions, and GeneXpert diagnostic testing. The primary exposure was the monthly number of days with PM2.5 concentrations ≥ 35 µg/m³, the U.S. EPA 24-hour air quality standard commonly used to characterize high-intensity pollution episodes. Sensitivity analyses evaluated alternative thresholds of 25 µg/m³ and 15 µg/m³. To account for TB’s prolonged incubation period, we examined lag periods of 6 to 18 months.
Results: Across the study period, 1,505,778 TB cases were reported. Higher PM2.5 exposure was associated with an increased incidence of TB in subsequent months. In the primary analysis, a 14-day increase in days exceeding 35 µg/m³ over the preceding 12 months was associated with a 2.2% increase in TB incidence (95% confidence interval: 1.0%, 3.4%). Associations were stronger at longer lags and attenuated at shorter lags, with estimates including the null at 6 months. Effect estimates were smaller at lower PM2.5 thresholds, with associations including the null at 15 µg/m³.
Conclusions: Elevated wildfire-related PM2.5 exposure was associated with a subsequent increase in TB incidence, consistent with air pollution contributing to the progression to active disease. Ambient air pollution may represent a modifiable risk factor for TB control, particularly in regions with increasing wildfire smoke exposure.
