Dhaka topped the world's dirty-air list, and winter hasn't started

At 11:10 on the morning of 6 October, Dhaka's air quality index read 213¹, "very unhealthy" and the worst of any major city in the world, ahead of Kuala Lumpur and Singapore². That was early October, before the dry season. Dhaka's air gets worse every winter, when brick kilns fire up and construction dust and traffic smoke hang in still air. The bad season has not even begun.

How bad is Dhaka's air, really?

Bad by any measure, and getting harder to ignore. In IQAir's 2025 world report, Bangladesh was the second most polluted country on earth, with average fine-particle pollution (PM2.5) of 66.1³ micrograms per cubic meter. That is more than 13 times WHO's guideline of 5. Dhaka had at least two months above 100.

In July, a team at Jahangirnagar University put a human number on it. Using data from 2013 to 2021, they estimated that PM2.5 causes about 242⁴ deaths a day across Dhaka, Chattogram, Rajshahi, Khulna, Sylhet and Barishal, about 88,240 premature deaths a year. Dhaka alone accounts for 68,703. They priced the loss at nearly $23 billion a year, almost 5% of GDP.

Estimates differ by method. An older World Bank figure put the national cost at 3.9⁷% to 4.4% of GDP, and a global estimate cited in the Dhaka Tribune attributed 236,000 Bangladeshi deaths⁵ to air pollution in 2021. Every serious estimate is large. None of them is small enough to treat as weather.

The biggest killer is heart disease, not coughs

Here is the detail in the new study that changes who owns the problem. Of the deaths it counted, about 37,519 a year were from heart disease, by far the largest cause the study reported. Chronic lung disease accounted for 8,344 and lung cancer for 811. Dirty air in Bangladesh kills more people through the heart than through the lungs.

That matters because we file air pollution under "environment", where nobody holds a budget for the damage. I have written that air quality is a health emergency nobody owns. The new data suggests the owner: whoever pays for cardiovascular care. Heart disease programs, insurers, large employers and hospital groups all carry this cost already. They just do not see it on the invoice.

Health businesses in Dhaka already plan for the season commercially. At Praava Health, our winter campaign drove hub footfall up about 190%. Winter demand is predictable, and private providers plan for it. If a private provider can plan for the winter wave, a public health system can plan to shrink it.

America is fighting over a number Dhaka would celebrate

The US has its own fight, at a far lower level. The American Lung Association's 2026 report found 152.3 million⁶ Americans, 44% of the country, live where ozone or particle pollution earns a failing grade. People of color are 42.1% of the population but 54.2% of those living in a county with at least one failing grade.

In 2024, the EPA tightened the annual PM2.5 limit from 12 to 9 micrograms. After the change of administration, the agency asked a federal appeals court to throw out its own standard. By late June, the D.C. Circuit had refused and left the limit in place, and a Supreme Court appeal is widely expected.

Put the two side by side. Bangladesh's national average is more than seven times the US limit that is being fought over in court. The US is arguing about the last few micrograms. Bangladesh is living with more than sixty. But the two share a harder lesson. An estimated 40% of Bangladesh's air pollution blows in from coal burning across its borders, and the 2023 Canadian wildfire smoke pushed pollution up across dozens of US states. Neither country can clean its air alone, which is exactly why each needs to protect people while the slow fixes happen.

What I would build before December

Cleaning the air is a decades-long policy job. Protecting people from it this winter is a communication and operations job, and that one can start now. At SureCash, we paid a government stipend to about 10 million people on mobile phones. The same reach can carry a warning. At Praava, the Lifebuoy hotline took about 3,000 calls a day, because help came through a channel people already trusted.

• Turn the AQI into an action. "AQI 213" means nothing to most people. "Keep children indoors this afternoon" means something. Send one action per alert by SMS, through the mobile operators and wallets people already use. My free risk communication calculator helps shape the message.
• Target the heart patients first. Clinics and pharmacies know who has heart disease. Message them directly on bad days: stay in, take your medicine, know the warning signs.
• Move the hours, not just the masks. Schools and employers can shift outdoor work and sport away from the dirtiest hours of the day.
• Make one clean room. A closed room with an air purifier in every school, clinic and office gives people somewhere to breathe during the worst hours.
• Price your own share. Count cardiac and respiratory visits on high-AQI days against clean days. My free prevention ROI calculator turns that gap into a budget case.

The same logic applies in a Detroit neighborhood near a highway or a Michigan town under wildfire smoke. The air will take years to fix. The warning can go out tomorrow.

The short version

• Dhaka's AQI hit 213 on 6 October 2026, the worst in the world, before the winter smog season.
• Bangladesh averaged 66.1 micrograms of PM2.5 in 2025, more than 13 times WHO's guideline.
• A new study links PM2.5 to about 242 deaths a day in six cities, about $23 billion a year, and heart disease is the biggest single cause.
• 152.3 million Americans live with failing air, and the EPA's 9-microgram limit survived a court fight in June.
• Assign the bill to heart health, then protect people now: action-based alerts, direct messages to heart patients, shifted hours and clean rooms.

If air pollution showed up as a line on your cardiology budget, what would you do differently this winter?

Md Shafaat Ali Choyon (MPH, CHES®, MBA, MCIM) is a growth, marketing and public-health strategist who builds and runs AI in production, with 17 years across telecom, fintech, e-commerce, consumer tech and healthcare in the US and Bangladesh. See the essays or the portfolio.