Bangladesh has long recognized that air pollution harms the lungs and heart, but the World Health Organization's (WHO) new report finds that it may also increase the risk of loss of brain function and dementia, providing further motivation to improve air quality.
In its updated Risk Reduction of Cognitive Decline and Dementia guidelines released this week, WHO for the first time recommends reducing exposure to both ambient and household air pollution to help prevent dementia.
This first major update since 2019 provides growing evidence that long-term exposure to air pollution is linked to declining brain health.
Globally, more than 57 million people are living with dementia, with over 60% residing in low- and middle-income countries.
With no widely available cure, the WHO says reducing preventable risk factors throughout life offers the best opportunity to lower the future burden of the disease.
The finding has particular relevance for Bangladesh, where a nationally representative study led by icddr,b and the National Institute of Neurosciences and Hospital (NINS) found that 8% of adults aged 60 years and above, which is about one in every 12 older Bangladeshis, are living with dementia.
The study was published in The Lancet Regional Health – Southeast Asia in 2023.
As the older adult population grows, health experts state the dementia burden will likely increase unless preventable risk factors are addressed.
“We know more today than ever before about what drives dementia risk, and these guidelines translate that knowledge into action,” WHO Director-General Dr Tedros Adhanom Ghebreyesus said in a statement announcing the updated guidelines.
A key change in the new guideline is the inclusion of air pollution as a modifiable environmental risk factor for dementia.
WHO now recommends reducing exposure to ambient air pollution, especially fine particulate matter (PM2.5), and household air pollution, as this may lower the risk of cognitive decline and dementia.
However, this recommendation is conditional because most supporting studies are observational and the certainty of evidence remains low.
Despite limited evidence, the guideline concludes that consistent findings of multiple studies and established health impacts of air pollution justify public health action.
Scientists cited by the WHO report that long-term exposure to pollutants such as PM2.5 may cause inflammation, oxidative stress, and vascular damage, which might impair brain function over time.
Why Bangladesh should pay attention
The WHO’s warning comes as Bangladesh continues to face hazardous air pollution, especially during the dry season, when Dhaka often ranks among the world’s most polluted cities.
Bangladesh, air pollution is caused by emissions from brick kilns, aging vehicles, industries, construction, and open waste burning.
While these pollutants are known to increase pulmonary and cardiovascular risks, WHO notes they may also affect cognitive health.
The guideline emphasizes that ensuring clean air is a societal responsibility.
It calls for measures including cleaner energy, better urban planning, traffic emission controls, and stronger environmental policies to reduce exposure for all.
Furthermore, the updated guidance advocates providing hearing aids to adults experiencing auditory decline, recognizing this as a key intervention to mitigate the risk of developing dementia.
For Bangladesh, where poor air quality and a rapidly aging population are converging, the updated WHO guideline highlights a new aspect of the country’s pollution crisis.