Poison in the air: Declining air quality in India.

Air pollution is a burgeoning environmental problem with potential for climate change. The worst-hit areas are the rapidly developing capital cities of low- and middle-income countries across the globe. Delhi, the capital of India, is no exception. In fact, Delhi was the most polluted of more than 1600 cities in the world according to the WHO's 2014 database for outdoor air pollution. The recent declaration of a public health emergency in and around the city speaks volumes about the declining air quality in India. Introspection into the various causes and mechanisms responsible for this sorry state of affairs, its impact on human health, and possible solutions to the problem is being reported.