Temporal Associations Between Ambient Air Pollutants and Inhaled Beclomethasone Dispensing in Brazil

Rationale : Air pollution is a recognized trigger of asthma exacerbations, but its influence on population-level demand for controller medications remains insufficiently quantified, particularly in middle-income countries. We assessed whether temporal variations in ambient air pollutants are associated with national dispensing of inhaled beclomethasone in Brazil. Methods : This nationwide ecological time-series study analyzed monthly data from January 2018 to December 2024. Aggregated beclomethasone dispensing data were obtained from the Brazilian Farmácia Popular program and standardized as doses per 100 inhabitants. Monthly mean concentrations of PM₂.₅, nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and black carbon were derived from the Copernicus Atmosphere Monitoring Service reanalysis. Seasonal ARIMA models with exogenous regressors (SARIMAX) were fitted, adjusting for relative humidity and including an indicator for the COVID-19 pandemic period. AIC/BIC and residual diagnostics guided model selection. Results : A total of 4.22 billion beclomethasone doses were dispensed during the study period, with consistent winter peaks. In multivariable SARIMAX models, higher concentrations of hydrophobic black carbon (β = 5.89×10⁹; p < 0.001) and SO₂ (β = 2.19×10⁹; p < 0.001) were positively associated with increased dispensing of beclomethasone canisters. In contrast, NO₂ (β = −2.24×10⁹; p < 0.001) and PM₂.₅ (β = −4.09×10⁸; p < 0.001) showed inverse associations, potentially explained by temporal lag and anticipatory medication renewal. The pandemic period was associated with a marked reduction in dispensing (β = −8.78; 95% CI − 10.81 to − 6.75). Conclusion : Air pollution was significantly associated with patterns of inhaled corticosteroid dispensing in Brazil, indicating that population-level therapeutic needs for asthma control mirror fluctuations in air quality.