Air pollution is a serious threat to the planet. The faster an economy grows, the more it pollutes the atmosphere. It's not just the cars and factories, the burning of solid fuels in developing countries also contributes to the problem. In fact, the way things are headed, everybody in big cities will be forced to wear gas masks in the near future. According to a recent survey by the World Health Organisation (WHO), 15 Indian cities feature in the top 30 most polluted cities in the world. In other words, half of the most polluted places on the planet are in India. This is a major cause for concern for everyone.

12. Gwalior

Gwalior is surrounded by 3 industrial areas: Sitholi, Banmore and Malanpur. The main industries in the city include tourism, dairy, chemical, manufacturing, and textiles, and this is why pollution in the city is on the rise.

11. Dehradun

Located in the Himalayas, Dehradun is one of the oldest Indian cities. Many government departments like the Indian Institute of Petroleum are located here and it is believed that they are contributing to the pollution.