Doctors say that children who spend more than five hours in front of the TV are at an increased risk of developing asthma.
Scientists at the Catholic University in Rome say that watching television for such long periods increases the danger by more than half as compared to children who watch TV for one hour.
They revealed that a study of 20,000 six and seven-year-olds has revealed that children who were TV or computer games fans were less active with poorer diets.
According to them, such children were also more likely to be exposed to second-hand smoking.
The researchers, however, stressed that the increased risk might also be due to a lack of sighing.
They point out that deep inspiration, the technical term for sighs, plays a significant role in helping lungs function but sitting for hours leads to shallow breathing.
"Prolonged sitting is associated with a decrease in spontaneous sighs, which regulate airways," the Mirror quoted Dr Giuseppe Corbo as writing in medical journal Epidemiology.
The researcher said that the study confirmed the link between obesity and asthma, and projected salt as the biggest risk.
The subjects having the highest intake of salt were two-and-a-half times more likely to develop asthma.
The British Lung Foundation said "couch potato" culture puts kids at risk.
"Obesity, high TV viewing and a high salt diet get children off to a bad start in life," added the foundation.