Dhaka, consistently ranked among the most polluted cities in the world, has been found to have air pollution levels more than five times higher than the World Health Organization's (WHO) recommended guidelines, according to a new study.

The research team was led by Shakhaoat Hossain, associate professor at the Department of Public Health and Informatics of Jahangirnagar University. Other team members were: Afsana Yasmin, Imran Ahmed, Maria Haider, Md Kamal Hossain and Mohammad Abdul Motalib.

The study titled “Characterizing indoor air quality and identifying factors influencing air quality at home microenvironment in Dhaka city” was published in the Indoor Environments journal on 11 October 2024.

The study sheds light on a growing health crisis that has largely been overlooked — indoor air pollution.

The study shows that the concentration of fine particulate matter (PM2.5) inside 43 households across Dhaka is alarmingly high.

The average PM2.5 level recorded was 75.69 micrograms per cubic meter, far exceeding the WHO guideline of 15 micrograms per cubic meter. In some cases, pollution levels exceeded 200 micrograms per cubic meter, pointing to severe indoor air quality issues in certain homes.

“This study underscores the severe risks posed by indoor air pollution, an often-neglected issue,” said Shakhaoat Hossain.

“While much attention has been focused on outdoor pollution, the dangers inside the home are just as significant, and we need to address them urgently,” he added.

Several factors contribute to Dhaka’s alarming indoor air pollution level. Among the key sources identified are chemicals from tire friction during road traffic, the burning of plastic in landfills, and the use of unrefined oil for cooking.

These pollutants infiltrate both indoor and outdoor environments, significantly deteriorating air quality.

The study highlights how outdoor polluted air enters homes, combined with long cooking hours, inadequate ventilation, and small room sizes, exacerbating the problem.

Women and children are particularly vulnerable, as they tend to spend more time indoors. According to the study, people typically spend 60-65% of their lives indoors, making indoor air pollution a critical public health concern.

Shakhaoat Hossain and his team emphasized the need to control household air pollution by preventing outdoor pollutants from entering homes and using HEPA-filter air purifiers to reduce indoor particulate matter levels.

Ensuring proper ventilation during cooking and using environment friendly cooking stoves can also help reduce exposure to harmful pollutants. Afsana Yasmin, a member of the research team, emphasised the importance of regular cleaning to reduce dust and pollutants and stressed improving indoor air quality through air conditioners.

“Indoor air pollution is responsible for nearly 70,000 deaths annually in Bangladesh, according to the State of Global Air report,” said Shakhaoat Hossain, calling for urgent government action.

He stressed the need for raising awareness, implementing comprehensive policies, and promoting clean cooking technologies to address this growing health crisis.