Vehicular pollution is the major reason for increase in asthma cases, say city doctors on World Asthma Day which falls on the first Tuesday of May every year (May 6).

A majority of respiratory physicians in the city say that out of the total number of out-patients, around 50 per cent suffer from asthma. It is a lung disease that narrows the airways thereby causing recurring periods of wheezing, chest tightness, and cough that normally occurs at night or early in the morning.