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Singapore’s smoking ban may have warded off 20,000 heart attacks in seniors

An extension of a smoking ban to communal areas of residential blocks and outdoor spaces in Singapore in 2013 may have prevented up to 20,000 heart attacks among those aged 65 and above.

This is according to Duke-NUS researchers who investigated the effects of the legislation. They found that the 2013 smoking ban was associated with a monthly fall in the rate of heart attacks, with older people and men benefitting the most.

This was the first local study investigating the effects of expanding smoke-free laws to outdoor areas, and the results were published in the journal BMJ Global Health.

Despite various restrictions and controls, tobacco continues to kill more than 10 million people globally every year, while second-hand smoke exposure is responsible for 1.3 million annual deaths around the globe, many of which are caused by heart attacks. In Singapore, too, one in ten Singaporeans still smokes, according to the 2020 National Population Health Survey.

In 2013, Singapore extended smoke-free legislation to all communal areas of residential housing blocks, where 80 per cent of the population lives, as well as outdoor spaces, including covered linkways, overhead bridges and within 5 metres of bus stops. This was further extended to reservoirs and parks in 2016, and to more educational institutions as well as more types of buses and taxis in 2017.

But what exactly is the impact of such laws? Existing evidence on the health benefits is largely confined to that of indoor smoking bans rather than those for housing estates and outdoor spaces. 

“Residents would likely frequent common areas in housing estates as part of their daily routine or when meeting with their friends and neighbours. If there are smokers around, these residents may be exposed to tobacco smoke. Having smoking bans in these areas would reduce their exposure to the smoke and consequently, reduce their risk of heart attacks,” said Dr Joel Aik, an adjunct assistant professor from the Health Services & Systems Research Programme at Duke-NUS and senior author of the study.

To assess the impact of the various pieces of legislation on heart attack rates, Dr Aik and his team analysed monthly reports from the Singapore Myocardial Infarction Registry from January 2010 to December 2019. During this period, 133,868 heart attacks were reported, 87,763 (66 per cent) of which occurred among men and 80,597 (60 per cent) of which occurred among those aged 65 and above.

Before the 2013 extension, the rate of heart attacks among those aged 65 and above was around 10 times that of those under 65 years of age. Men in particular, were at risk, with almost twice as many men than women suffering a heart attack . The overall number of heart attacks rose by a rate of 0.9 cases per million people every month before the 2013 extension. But afterwards, this rate fell to 0.6 cases per million people.

Seniors and men were the primary beneficiaries of the extended ban. The monthly fall in heart attack rate among those aged 65 and above was 5.9 cases per million people. This fall in the rate is almost 15 times greater than that in younger individuals, which stood at 0.4 cases per million people.

According to their calculations, the researchers also estimated that an additional 19,591 heart attacks might have occurred in those aged 65 and above, compared with 1,325 in the under-65s had the legislation not been enacted. Potentially, 4,748 cases were averted in men.

The impact of the subsequent changes to the legislation, however, was not clear yet from the data. The extension of smoke-free laws to reservoirs and more parks was not associated with a significant reduction in the number of heart attacks. This could have been due to better diagnostic technology, which can detect more cases of heart attack.

While the 2017 legislation was not associated with a significant decline in overall heart attack incidence, the researchers found that the average decline in the rates was consistent among those of different age groups and among men and women. This consistency suggests that the ban may well have been beneficial though more studies are required to validate this.

Professor Patrick Tan, Senior Vice-Dean for Research at Duke-NUS, said: “Smoking remains an unresolved epidemic in Asia, with majority of tobacco consumers being in the region. This study provides additional evidence for policy makers who are looking to expand their smoke-free laws to mitigate the adverse impact of exposure to tobacco smoke and reduce the health burden of heart diseases for their residents.” 

To Dr Aik, his research also hit home in more ways than one. His grandma had passed away from stomach cancer, likely linked to her long-term smoking habit.

“Because of my grandma, I feel driven to contribute to the body of research on anti-smoking initiatives. Tobacco consumption and exposure to environmental tobacco smoke is harmful to health. If more smokers are be able to kick their smoking habit and lead a healthier lifestyle, we will be able to save more lives. I hope our findings can bring about targeted and effective action to benefit more people like my grandma.”