Indoor air quality in Dhaka venues that allow smoking is worse than outdoor, says a study

Research carried out in six cities, including Dhaka, with dangerous levels of air pollution indicates that air quality inside venues that allow smoking is even worse than outdoor air.

The study, published in the journal Nicotine & Tobacco Research, has been 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 Pakistan’s Islamabad, Indonesia’s Denpasar, Chad’s N’Djamena, Bangladesh’s Dhaka, India’s Delhi and Mexico City.

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 Organisation’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.

"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.”

Over the 626 visits made during the study, smoking was observed in almost a third of the venues, ranging from 5 percent of sites in India to 72 percent in Chad.

Fine particle (PM2.5) levels were, on average, some 34 micrograms/ m3 higher in venues where smoking occurred compared with venues where smoking was not observed. It is 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 nine percent in Bangladesh.

“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,” said co-author Dr Sean Semple, Senior Lecturer at Aberdeen University.

“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.”

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.

WHO estimates that tobacco kills 57,000 people in Bangladesh every year and affects more than 350,000 people.