PM 2.5 , O 3 and survival gains from China’s clean air actions among patients with lung cancer: a 20-year registry-based cohort study in Beijing
Lei Yang, Ning Kang, Tao Xue, Ning Wang, Shuo Liu, Huichao Li, Xi Zhang, Lili Cao, Xiaolin Ma, Shaohua Ma, Jiafu Ji, Tong ZhuBackground
In recent years, China has experienced declining fine particulate matter (PM 2.5 ) levels but rising ozone (O 3 ) levels. We aimed to examine the independent and joint associations of long-term exposure to PM 2.5 and O 3 with all-cause mortality among patients with lung cancer and to estimate potential survival gains.
Methods
We included 172 845 lung cancer patients diagnosed in 2003–2022 from the Beijing Cancer Registry. Three-year average pre-diagnosis PM 2.5 and O 3 were assigned using the ChinaHighAirPollutants dataset. Cox proportional hazards models were used to estimate associations of PM 2.5 and O 3 with mortality. Joint exposure-response patterns were examined using a two-dimensional tensor-product spline and quantified by the multiplicative interaction index. Model-estimated avoided deaths and extended expected lifespan (EEL) were calculated using counterfactual simulations based on 2013 exposure levels.
Results
Both PM 2.5 and O 3 were associated with increased mortality among patients with lung cancer, with HRs of 1.111 for PM 2.5 (95% CI 1.083 to 1.140) and 1.117 for O 3 (95% CI 1.070 to 1.166) per 10 μg/m 3 increase. A significant multiplicative interaction was observed between PM 2.5 and O 3 , with statistically significant positive interactions mainly occurring at higher O 3 concentrations (>105 µg/m 3 ). During 2016–2022, reductions in pre-diagnosis PM 2.5 exposure were associated with 13 229 model-estimated avoided deaths and a 7.8-month increase in 5-year EEL. However, O 3 and the PM 2.5 -O 3 interaction offset approximately 40% of these benefits.
Discussion
PM 2.5 reduction was associated with substantial survival gains among lung cancer patients, but rising O 3 and pollutant interactions partly offset these benefits, supporting coordinated multipollutant control.