Intervention tool: WeChat
TTM
PMT
WeChat is the most popular Chinese social media app, which our information technology team used to deploy the messages. The application evaluated the PMT construct score by asking questions and recording information; then, it automatically calculated the lower score of the sub-content that needed to be strengthened. Specifically, the scale comprised 21 items using a seven-point Likert-type scale with responses ranging from 1 (definitely disagree) to 7 (definitely agree). Each construct subscale of PMT included three items, and we computed the mean of the subscale score. The TTM stage was also identified according to the smoking status of users. Then, WeChat issued personalised text messages according to the evaluation, as detailed elsewhere. Details on the scales and the processes are available elsewhere [