Smoking causes cardiovascular and respiratory diseases, cancers and diabetes, and it has been a leading risk factor for death globally. Despite the availability of smoking cessation services locally, most smokers do not use such services. Workplace is one of the most convenient platforms to provide smoking cessation services and over 55% of smokers are employed according to the local population-based survey. However, the effectiveness of a smoking cessation programme conducted in workplace is yet to be examined in Hong Kong, and the attitudes and practices of corporations in promoting smoking cessation are not clear. Thus, this study aims to examine the employers'/ managerial staff's knowledge, attitudes and practices in promoting smoking cessation in workplace and evaluate the smoking behaviors of participants before and after attending a smoking cessation intervention.

This study will separate into two phases. Phase I is a large scale cross-sectional survey to corporations in Hong Kong to examine the employers' knowledge, attitudes and practices in promoting smoking cessation in the workplace. Phase II is a 2-arm randomized controlled trial will be conducted to examine the effectiveness of WhatsApp intervention.

Outcome:

The primary outcome of the study is to measure participated smokers' self reported 7-day point prevalence quit rate at 6-month follow-up. Secondary outcomes include participated smokers' (i) self reported 7-day point prevalence quit rate at 9- and 12-month follow-ups; (ii) self-reported reduction rate at 6-, 9- and 12-month follow-ups; (iii) self-reported quit attempt at 6-, 9- and 12-month follow-ups; (iv) change in self-efficacy towards smoking cessation at 6-, 9- and 12-month follow-ups compared with baseline.

Data analyses

Phase I:

Descriptive statistics will be used to measure the (1) basic information of the corporations, including the total number of employees and smoking employees; (2) knowledge on smoking of employers/managerial staff; (3) attitudes on smoking cessation of employers/managerial staff; (4) practices of the corporations with respect to smoking cessation.

Phase II:

Descriptive statistics such as frequency, percentage, and mean will be used to summarize the outcomes and other variables. Chi-square tests and t-tests will be used to compare outcome variables between subgroups. The intention-to-treat analysis will be used such that those lost to contact and refused cases at the follow-ups will be treated as no reduction in cigarette consumption nor quitting. Subgroup analyses will be conducted among the "adherence" cohort, which is classified as subjects who actively participant in the WhatsApp interaction.

Inclusion Criteria:

• Hong Kong residents aged 18 or above
• Smoke at least one cigarette per day
• Able to communicate in Cantonese/Mandarin and read Chinese
• Able to use instant messaging tool (e.g. WhatsApp) for communication
• Stay at Hong Kong during the intervention and follow-up periods (12 months)

Exclusion Criteria:

• Smokers who are psychologically or physically unable to communicate
• Currently following other smoking cessation programme(s)