Estimated burden of disease and health effects attributable to fine particulate matter and ozone exposure in relation to COPD and cardiovascular disease in Upper Northern Thailand

• The burden of disease attributable to PM 2.5 exposure was estimated in Upper Northern Thailand. • Long-term PM 2.5 exposure has a positive relative risk of lung cancer and cardiopulmonary disease. • PM 2.5 exposure was significantly associated with increased COPD risk only in Lampang province. • Joint exposure to PM 2.5 and ozone (O 3 ) was significantly associated with increased COPD risk in Chiang Mai, Chiang Rai, and Nan provinces. • The study showed that there were synergistic effects of PM 2.5 and O 3 in Nan province on the incidence rate ratios of COPD and CVD. Fine particulate matter (PM 2.5 ) is a significant contributor to air pollution and is associated with many diseases of global public health concern. In this study, the burden of lung cancer and cardiopulmonary disease attributed to PM 2.5 exposure in Thailand's upper northern region is estimated. Additionally, generalised additive models (GAMs) were used to examine the relationship between PM 2.5 and ozone (O 3 ) levels and the incidence of cardiovascular diseases (CVDs) and chronic obstructive pulmonary disease (COPD). The results indicated all eight provinces showed a positive relative risk (RR) for lung cancer and cardiopulmonary disease. The estimated long-term exposure to PM 2.5 during 2015–2023 showed that the regional average relative risk (RR) was 1.558 (95% CI: 1.530–1.586) for lung cancer and 1.344 (95% CI: 1.328–1.361) for cardiopulmonary disease. This study examined the short-term effects of PM 2.5 and ozone (O 3 ) exposure on morbidity from COPD and CVD. PM 2.5 exposure was significantly associated with increased COPD risk only in Lampang province, where the incidence rate ratio [IRR] was 1.009 (95% CI: 1.002–1.017), p < 0.05. Ozone exposure showed significant associations with COPD risk in Chiang Mai, Chiang Rai, and Nan provinces, with IRRs of 1.021 (95% CI: 1.009–1.033), 1.020 (95% CI: 1.007–1.032), and 1.026 (95% CI: 1.012–1.040), respectively (p < 0.05). Ozone exposure was associated with CVD risk in Chiang Mai, Chiang Rai, and Nan provinces, but the strength of the association was not statistically significant. Similarly, no significant association was observed between short-term PM 2.5 exposure and CVD. Joint exposure to PM 2.5 and O 3 was significantly associated with increased risk of COPD in Chiang Mai, Chiang Rai, and Nan provinces (p < 0.05). Interaction analyses revealed synergistic effects on COPD in Nan and CVD in Ching Rai and Nan. Male sex, older age (≥ 60 years), and seasonal variation of particulate matter and ozone concentration were identified as significant effect modifiers. These findings elucidate the differential impacts of air pollutants on respiratory and cardiovascular health in northern Thailand. Furthermore, they emphasise the heightened vulnerability of older adults and males, underscoring the urgent need for targeted, region-specific public health interventions.