Introduction
The phenomenon of dual use, defined as the concurrent use of both combustible cigarettes and electronic cigarettes (e-cigarettes), poses a complex challenge to tobacco harm reduction strategies. While some public health stakeholders consider dual use a transitional phase towards complete smoking cessation, others warn it may sustain nicotine addiction and complicate risk assessments. The critical question centers on whether dual use represents a harm reduction benefit or a perpetuation of tobacco-related health risks. Understanding the patterns and trajectories of dual use in real-time is thus essential to deciphering its true impact on smoking behaviors and health outcomes.
