A comprehensive comparison of the life-cycle environmental impacts of traditional and returnable express delivery packaging in China

China's express delivery service industry has been experiencing rapid development; in 2021, deliveries reached a total of 108.29 billion. However, with the increasing demand for express packaging and the accompanying environmental pressures, the widespread adoption of returnable mailing packaging has become a key consideration to promote the reduce, reuse, and recycle (3R) concept. This study performed a life cycle assessment (LCA) and analyzed the environmental impacts of returnable packaging with respect to those of traditional packaging. Five scenarios were established, including traditional express bags and boxes as well as returnable bags and boxes. Results revealed that the comprehensive environmental impact value of returnable packaging bags is 1.75 × 10⁻⁵ per capita equivalent (PE), representing 59% and 26% reductions compared to the waste incineration and recycling paths of plastic bag packaging, respectively. Additionally, the comprehensive environmental impact value of box-type returnable packaging is 1.85 × 10⁻⁴ PE, which is 63% lower than that of carton-type express packaging. To reduce pollution and greenhouse gas emissions, returnable express boxes and bags should be reused at least five and fifteen times, respectively.