An extension of the smoking ban to communal areas of residential blocks and other 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 the first local study investigating the effects of expanding such laws to outdoor areas.
The research, published in the open access journal BMJ Global Health, was led by scientists from Duke-NUS Medical School. Their study showed that the extension of the smoking ban was associated with a monthly fall in the rate of heart attacks, with older people and men benefitting the most.
Second-hand smoke exposure is responsible for 1.3 million annual deaths around the globe, many of which are caused by heart attacks. But the existing evidence on the health benefits of comprehensive smoke-free laws, which many countries (67 since 2003) have implemented, is largely confined to 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.
In 2013, Singapore extended smoke-free legislation to all communal areas of residential 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 all residential parks in 2016, and to more educational institutions as well as more types of buses and taxis in 2017.
To assess the impact of the various pieces of legislation on heart attack rates, the researchers 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. The rate of cases among men was nearly double that of women. 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 scientists 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 was not as clear when studying the impact of legislation in subsequent years. From 2016, 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 following this prohibition extension to more universities and more types of buses and taxis was consistent among those of different age groups and among men and women. This consistency in findings 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.”
Reference:Ho, J.S. et al. (2023) ‘Association between the extension of smoke-free legislation and incident acute myocardial infarctions in Singapore from 2010 to 2019: An interrupted time-series analysis’, BMJ Global Health, 8(10). doi:10.1136/bmjgh-2023-012339.