Postcard from... Delhi

Spend two days in Delhi, India's capital and the second biggest city in the country, and your snot will be black.

Obviously, the colour of your mucus is just the tip of the country's polluted iceberg. A Yale-Columbia study released earlier this year showed that India has the most toxic air in the world; a serious health problem that can only get worse if no concrete measures are taken.

The government, health and environmental organisations all agree on the fact that the small three-wheeled motorised rickshaw, a defining icon of the Indian metropolis, might be part of the answer.

Delhi's 55,000 yellow and green auto rickshaws have been required to run on clean-burning natural gas for the past few years, which would have made a huge environmental difference if the number of cars purchased at the same time hadn't increased dramatically. Delhi counts six million vehicles and approximately 1,200 more enter the crazy traffic jam every day.

Rickshaws don't have doors, and convincing those who can afford a car that they should ride in a small, bumpy vehicle when the air is so hot in summer, so cold in winter, and always badly polluted can be tricky, especially during the rush hour bedlam.

In the next five years, the maximum speed at peak hours is expected to drop to a miserable 5km per hour on all major roads in the capital. Rickshaws don't have doors and, in the short term, may further discolour your nostrils' contents. But they do go faster.