World
Delhi haze: Schools and colleges closed as pollution worsens
The combination of factors such as vehicle and industrial emissions, dust and weather patterns make Delhi the most polluted capital in the world. The air becomes especially toxic in the winter months when farmers in neighboring states burn straw. And the fireworks during the Diwali festival, which take place at the same time, only worsen the air quality. Low wind speeds also play a part because it traps pollutants in the lower atmosphere.