Introduction:
Over 20 cities in China have enacted local smoke-free laws or regulations that prohibit smoking in public places. However, only two of these smoke-free cities, Hong Kong and Tianjin, have examined the health impact of the law. Enacted in August 2013, Qingdao’s smoke free-law was stricter than most other municipal smoke-free laws because it closed the loophole allowing designated smoking rooms.

Objectives:
To estimate the health impact of the smoke-free legislation in Qingdao and to explore reasons for the disparity in the magnitude of the effect across smoke-free cities in China.

Methods:
A study with interrupted time-series design with adjustment for underlying secular trend, seasonal pattern, meteorology factors was conducted to determine the impact of the smoke-free law on acute myocardial infarction (AMI) and stroke events among permanent residents aged 35 years or older in Qingdao, China. Outcome measures were the weekly number of hospitalizations and deaths due to AMI and stroke derived from electronic medical records and an all-cause mortality surveillance system. The study period was from 1 January 2010 to 31 December 2015, with a post-ban follow-up of about two and a half years.

Results:
Following the smoke-free legislation, an incremental 20% (95% CI: 14%-26%) decrease in the trend per year was observed in AMI admissions. Gradual reductions in AMI admissions were found in both younger and older age groups. A 6% (95% CI: 1%-12%) and 13% (95% CI: 8%-18%) annual decrease in AMI mortality rate and stroke admissions among those aged between 65 and 84 years was observed respectively.

Conclusion(s):
The smoke-free legislation in Qingdao was associated with gradual reductions in fatal and nonfatal AMI and stroke events. Demonstrable but modest effects on stroke admissions and AMI/stroke mortality rate were observed among the older age group after the law had been implemented for about one year. The study indicates the urgent need to strengthen the monitoring and implementation of the current smoke-free legislation in Qingdao.