PM₂.₅ Reduction and Lung Cancer Mortality Trends in OECD Countries and Taiwan, 1998–2022: A Re-Examination of Association

Background: Lung cancer remains the foremost cause of cancer mortality worldwide. Although smoking continues to be the principle risk factor, PM₂.₅ has been identified as an important environmental carcinogen. Despite this, it is unclear whether improvements in PM₂.₅ translate into measurable reductions in lung cancer mortality over time.
Aim: To examine the relationship etween long-term PM₂.₅ exposure and lung cancer mortality across OECD countries and Taiwan while accounting for smoking and occupational exposure.
Methods: A longitudinal ecological study using panel data from OECD countries and Taiwan was conducted. Descriptive analysis, joinpoint regression, and two-way fixed effects regression with Driscoll–Kraay robust standard errors were applied using lagged exposure models.
Results: Lung cancer mortality and PM₂.₅ concentrations generally declined across most countries. Male mortality showed more consistent declines than female mortality. PM₂.₅ and smoking remained positively associated with lung cancer mortality, although smoking contributed the largest proportion to mortality variation (65.8%), followed by occupational exposure (25.8%) and PM₂.₅ (8.4%).
Conclusion: PM₂.₅ remains associated with lung cancer mortality despite improving air quality; however, smoking remains the dominant contributor to mortality trends. Integrated strategies combining tobacco control, environmental regulation, and occupational health policies are essential for reducing lung cancer mortality.
Key words: Lung cancer mortality; PM₂.₅; smoking; occupational exposure; OECD countries; Taiwan.