Estimation of hospital visits for respiratory diseases attributable to PM₁₀ from vegetation fire smoke and health impacts of regulatory intervention in Upper Northern Thailand

The air quality in Upper Northern Thailand (UNT) deteriorates during seasonal vegetation fire events, causing adverse effects especially on respiratory health outcomes. This study aimed to quantitatively estimate respiratory morbidity from vegetation fire smoke exposure, and to assess the impact of a burning ban enforced in 2016 on morbidity burden in UNT. We computed daily population exposure to fire-originated PM₁₀ and estimated its health burden during a 5-year period from 2014 to 2018 using daily fire-originated PM₁₀ concentration and the concentration-response function for short-term exposure to PM₁₀ from vegetation fire smoke and respiratory morbidity. In subgroups classified as children and older adults, the health burden of respiratory morbidity was estimated using specific effect coefficients from previous studies conducted in UNT. Finally, we compared the health burden of respiratory morbidity before and after burning ban enforcement. Approximately 130,000 hospital visits for respiratory diseases were estimated to be attributable to fire-originated PM₁₀ in UNT from 2014 to 2018. This estimation accounted for 1.3% of total hospital visits for respiratory diseases during the 5-year period, and 20% of those during burning events. Age-specific estimates revealed a larger impact of PM₁₀ in the older adult group. The number of hospital visits for respiratory diseases attributable to fire-originated PM₁₀ decreased from 1.8% to 0.5% after the burning ban policy was implemented in the area. Our findings suggest that PM₁₀ released from vegetation fires is a health burden in UNT. The prohibition of the burning using regulatory measure had a positive impact on respiratory morbidity in this area.