Byrnihat looks like many other towns in India's picturesque northeastern states of Assam and Meghalaya. But while it is nestled among lush green hills and scenic river valleys, it holds the unwanted title of the world's most polluted city, according to Swiss air quality monitor IQAir's 2024 report.

Walking along the town's hilly roads on a rainy afternoon, the views and stillness are only broken by the rhythmic clanking from nearby factories.

This town of about 50,000 people is also home to about 80 industries, many of them focused on iron and steel. The serpentine roads are lined with long rows of trucks — some stalled, others hauling goods to and from factories.

The National Highway 40 (NH40) cuts through the town, which straddles the border between Assam and Meghalaya states.

According to IQAir's Armen Araradian, Byrnihat's air had an average PM2.5 concentration of 128.2 micrograms per cubic meter in 2024. That is more than 25 times higher than what the World Health Organization (WHO) considers safe to breathe.

Dr. Prasanta Kr Brahma has spent eight years treating patients in Byrnihat. He said he has seen an "increasing number of cases of respiratory tract infection and other issues related to pollution."

According to government data analyzed by IQAir, the number of cases of respiratory infection in the region rose 76.77% between 2022 and 2024.

"Over the years, cancer has also become very common, especially head and neck cancer (HNC), which is related to air pollution," Dr. Brahma........

© Deutsche Welle