Delhi is now considered the most polluted city on earth. The lack of clean air has made the Capital more prone to illnesses and according to reports even forced officials who planned US president Barack Obama's visit to Delhi to cut down on his exposure outdoors.

The sudden rise in air pollution levels has made life difficult for most but has affected one particular section more than others. These are the children and the elderly who suffer from asthma.

ET Magazine asked Dr Vikram Jaggi of the Asthma Chest & Allergy Centre to offer his take on how bad the situation is for asthmatic patients in Delhi and to offer representative case studies of people who suffer on account of the pollution (see Pounded by Pollution). Here are the doctor's observations:

The quality of the air in general and the levels of air pollution in particular affect the lungs of the people who breathe this air. Even generally healthy individuals are affected but the most badly hit are the very young and the very old asthma patients.

When we think of pollution, we naturally think first of outdoor pollution: traffic and factory smoke. But there is another kind — indoor pollution related to burning of biomass such as gobar, wood and coal for cooking and heating. This is also an important health issue in India, particularly among the poor and the less privileged.

With increasing pollution and smog in the cities, doctors are seeing more and more cases of respiratory diseases. Coughing, wheezing and chest congestion are now more common than they were a few decades ago.