Air pollution is made partly of tiny bits called PM2.5 that are so small they slip deep into your lungs. A study looked at air pollution across India and how many people died.
The scientists estimated that dirty air is linked to about 1.5 million extra deaths a year in India, compared to if the air met health guidelines. In the city of Delhi, the pollution has been more than 20 times higher than the level health experts say is safe.
That number is huge, but it is an estimate, not a list of names. Scientists use math and models to guess how many deaths are linked to pollution, and different methods give different totals. Even so, many studies agree that dirty air is a serious danger to health in India.