Wildfire-related PM_2.5 and cause-specific cancer mortality

Wildfires have devastating effects on society and public health. However, little evidence from population-based cohort has been performed to analyze the relationship of wildfire-related PM_2.5, an important component of wildfire smoke, with cancer-specific mortality. We aimed to explore this relationship and identify vulnerable populations in UK with lower levels of wildfire-related PM_2.5 exposure. The study consisted of 492394 participants (age: 38-73 years) recruited by UK Biobank during 2004-2010. The cumulative wildfire-related PM_2.5 within 10 kilometers of residence over three years was used as exposure, which was assessed by chemical transport and machine learning models. A time-varying Cox regression was utilized to explore the relationship of exposure with diverse cancer-specific mortality outcomes. Subgroup analyses of a range of potential modifiers were performed. Each 10 μg/m³ increment of 3-year cumulative exposure was related to a 0.4 % greater risk of total cancer (95 %CI: 1.001-1.007), a 1.1 % greater risk of lung cancer (95 %CI: 1.004-1.018), and a 2.7 % greater risk of lip, oral cavity and pharynx (LOP) cancer (95 %CI: 1.005-1.049). Higher vulnerability in the wildfire-related PM_2.5-lung cancer relationship was found among participants being retired than those with other employment status. Even lower levels of exposure to PM_2.5 from wildfires were related to elevated mortality risks for cancer from total, lung, LOP, highlighting the importance of wildfire prevention and control. Further investigations are warranted to enrich and extend existing knowledge in this field.