Research carried out in six cities with dangerous levels of air pollution indicates that air quality inside venues that allow smoking is even worse than outdoors. The study, published in the journal Nicotine & Tobacco Research, was co-authored by tobacco control experts at the International Union Against Tuberculosis and Lung Disease [The Union] and the University of Aberdeen, Scotland.
The study used a low-cost monitoring device to gather objective air quality data by measuring fine particulate matter (PM2.5) in around 100 hospitality venues in each of the six cities. National smoke-free legislation - banning smoking in indoor public places - is in force in each of the locations. Readings were taken in cafes, bars and restaurants to reveal levels of compliance with smoke-free rules in Islamabad (Pakistan), Denpasar (Indonesia), N'Djamena (Chad), Dhaka (Bangladesh), Delhi (India) and Mexico City (Mexico). During the same time period, air quality was also measured outside.
In all cities - with the exception of Mexico City - the average outdoor air pollution exceeded safe levels specified by the World Health Organization's [WHO] 24-Hour Air Quality Guidance for PM2.5 (25 micrograms/m3). And across all cities, where smoking was observed in venues, the indoor air quality was on average substantially poorer than the outdoor air.
'We often hear about how bad outdoor air quality is in the cities we studied, but there is little attention paid to how pollutant levels are frequently even worse indoors when smoking takes place,' said author Dr Angela Jackson-Morris, Senior Grants Officer at The Union's Department of Tobacco Control. 'These six countries already have legislation to prohibit smoking in bars, cafes and restaurants - it is now time to make sure it is implemented to protect people from the cancers and cardiovascular disease caused by breathing in second-hand tobacco smoke. The data clearly shows that if smoke-free laws are poorly enforced then people remain exposed to high levels of second-hand smoke with the well-recognised health risks that involves.'
Over the 626 visits made smoking was observed in almost one-third of venues, ranging from 5 per cent of sites in India to 72 per cent in Chad. Fine particle (PM2.5) levels were, on average, some 34 micrograms/ m3 higher in venues where smoking occurred compared to venues where smoking was not observed - a statistically significant finding. Smoke-free compliance varied considerably between countries. Smoking was evident in the majority of venues in Chad, nearly half of venues in Indonesia, but just 9 per cent in Bangladesh.
'This study shows that we can use low-cost methods to measure air quality in bars and restaurants around the world,' said co-author Dr Sean Semple, Senior Lecturer at Aberdeen University. 'These results show that this inexpensive technology can provide the objective data so crucial for presenting evidence about second-hand tobacco smoke to stakeholders and policymakers involved in public health globally. We hope these methods can be used locally to help build a case for improving enforcement of smoke-free laws in cities where current levels of compliance are inadequate.'
The device used to measure air quality in this research has previously been used with success to measure second-hand smoke levels in countries where outdoor air pollution levels are lower. This study is the first to use these instruments in low- and middle-income countries with higher outdoor concentrations of PM2.5.
Having established the feasibility of this method in locations with poorer outdoor air quality, the research team will now make technical guidance and simplified software for downloading data available online. It is designed to be used with observational assessments of smoke-free compliance.
There is no safe level of exposure to second-hand smoke. Harms to health include cancers, heart disease and severe respiratory illnesses. Major progress has been made globally on banning smoking in public places, but as this study indicates, more needs to be done. Tobacco kills nearly six million people globally every year.
Find out more about smoke-free policies here.