Due to issues arised from the collaboration contract between sponsor and research site

The goal of this clinical trial is to evaluate effectiveness of using e-cigarettes as harm reduction strategy for smoking cessation and decreasing risk of diseases in heavy smokers. The main questions it aims to answer are:

• Is there any effectiveness of using E-cigarette as a harm reduction strategy for smoking cessation?
• what are the impacts of using E-cigarette on respiratory function and risk of COPD?
• Assess the exposure to harmful and potential harmful constituents (HPHCs) of using E-cigarette

Participants will be randomized into a 6 months single-center, open label trial comparing study outcomes among 2 arms: health counselling, E-cigarette + health counselling. The EC arm will receive EC for 1 month. All 2 arms will receive health counselling from a licensed mental health counselor. After baseline, participants will report their use of combustible cigarette in both arms and EC use in the EC arm every day via online questionnaire in Wechat for behavioral monitoring.

If there is a comparison group: Researchers will compare health counselling group to see if E-cigarrette intervention is an effective way to stop smoking, and if there any change in respiratory function and change in exposure to harmful and potential harmful constituents (HPHCs).

Inclusion Criteria:

• 18 to 60 years old, gender is not limited
• The nicotine dependence test (FNDT) result score is 6-10 points
• Self-reported smoking at least 10 cigarettes a day, and smoking for at least 3 years
• Self-reported no current willingness to quit smoking
• Self-reported difficulty controlling the need to smoke, or smoking while sick in bed
• Must not accepted smoking cessation treatment in the last 3 months according to the self-report
• Must have never tried e-cigarette before
• Must be able to fully understand the purpose, nature and content of the research, and voluntarily sign the informed consent form as a subject
• Must agree and able to communicate well with the researcher, and able to complete the online questionnaire and examination in accordance with the research regulations.

Exclusion Criteria:

• Self-reported pregnant or breastfeeding
• Severe disease (defined as an illness or condition that put the patient at risk, interfere the trial results, or affect the patient's ability to participate in the trial judged by the panel)
• Past diagnosis of COPD, lung cancer, pneumoconiosis, bronchiectasis, interstitial lung disease, bronchial asthma, or other restrictive ventilatory disorder
• Living with severe heart, brain, liver, kidney, blood system diseases or malignant tumors
• Moderate-severe renal impairment, or creatinine clearance (CCr) ≤50ml/min
• Phenylpyruvaturia
• Allergic predisposition (be allergic to two or more substances), and is allergic to any of the components in e-cigarettes or e-liquid (e.g., benzoic acid, propylene glycol, glycerin, nicotine, etc.)
• Already been enrolled into a smoking cessation treatment, including but not limited to nicotine replacement therapy (NRT), varenicline, bupropion
• Living with mental illness, a history of chronic alcoholism, drug abuse, or any factor that affects compliance
• Participating in other clinical trials
• Life-threatening condition with a life expectancy less than 1 year
• Researcher believes that it is not suitable to participate in this researcher.