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.

6. Amritsar

The Golden Temple sees thousands of pilgrims and tourists on a daily basis. The resulting traffic and congestion in the city adds to the pollution.

5. Ahmedabad

It's the 5th largest city in India and also the 3rd fastest growing city in the world. But pollution here seems to be increasing at the same rate at which the city is expanding.