Treatment costs and determinants in PM2.5-attributable respiratory diseases: evidence from Northern Thailand

Background Environmental issues related to air pollution in Southeast Asia have persisted for more than a decade, especially in Thailand. This study aims to estimate the treatment costs of respiratory diseases caused by exposure to ambient PM₂.₅ and to identify the factors that influence these costs. Methods This retrospective study analyzed secondary data on OPD and IPD respiratory disease treatment costs from government hospitals, along with ambient PM₂.₅ data from low-cost monitoring stations, to estimate the cost of illness across 25 districts in Chiang Mai during Thailand’s fiscal year 2023. Economic cost was estimated using the Cost-of-Illness method formula: Economic Cost Loss = Health Impact × Treatment Cost. K-means cluster analysis was used to classify estimated costs into minimum, medium, and maximum cost scenarios. Multiple linear regression was applied to identify significantly associated factors with treatment cost. Results Under the maximum cost scenario identified through K-means cluster analysis stratification, the total treatment cost associated with an average PM₂.₅ concentration of 42.59 µg/m³ was 460,122.58 USD, averaging 41.62 USD per case. Each 1 µg/m³ increase in PM2.5 was associated with a cost rise ranging from 403.84 to 13,159.87 USD. Non-infectious respiratory diseases incurred costs approximately two times higher than infectious ones. The estimate of maximum treatment burden for respiratory disease cases was highest in urban areas, totaling 102,878.88 USD. The urban area showed a significantly higher cost of treatment both in OPD and IPD cases (p < 0.001). Moreover, higher healthcare levels and older age were associated with higher costs in OPD cases. In IPD cases, length of hospital stay was a significant predictor. Conclusions Ambient PM₂.₅ exposure contributes significantly to the economic burden of respiratory diseases in polluted areas. These highlight the importance of pollution control policies and healthcare resource planning in high-risk areas. Trial registration not applicable.