Why More Asthma Cases?
As the number of children with asthma continues to increase, a natural question you might have is why? The answer, though, may not be clear and has been the cause of much discussion inside and outside the medical and scientific communities.
Younger Patients
One part of the increase may be related to the number of infants and toddlers being diagnosed with asthma. For many years, the medical community believed that children younger than three years could not have asthma. Instead, their providers would diagnose them, for instance, with conditions such as wheezy bronchitis or an upper respiratory infection.
Today, it is known that even infants may exhibit repetitive symptoms that suggest an asthma diagnosis. And, the sooner they are treated, the sooner they can feel better and avoid possible lung damage in the future.
Also, through medical technology, more babies born at lower birth weights are surviving. However, studies have shown that a lower birth weight may be associated with more respiratory symptoms and asthma during the child's younger years.
Also, other studies have linked frequent respiratory infections during a child's early years with the development of asthma, especially if that child has a history of eczema and/or allergies or parents with asthma or allergies.
A Too-Clean Environment?
One theory proposed to explain the increased prevalence of asthma is sometimes called the “hygiene hypothesis.” This idea suggests that because personal and public hygiene have improved in recent years, children now get fewer infectious diseases during early childhood and are treated with antibiotics more frequently than many years ago.
Essential
The hygiene hypothesis suggests that as a child's immune system develops, his body responds to allergens and pollutants rather than bacteria and viruses. As a result, the immune system becomes “biased” toward allergic responses.
In turn, this leads to an increased incidence of asthma — particularly among individuals who have family histories of asthma and allergies. On the other side, if a child is exposed to infections earlier in life, he may have a reduced risk of asthma or allergic diseases. While the hypothesis continues to be studied, this may explain the association between large family size, later birth order, daycare attendance, and reduced asthma risks.
Pollutants in the Environment
Conversely, some have pointed to increases in outdoor air pollutants. The National Institute of Environmental Health Sciences (NIEHS), a part of the National Institutes of Health (NIH), found in a study of air pollution levels of ten Southern California cities that the closer children live to a freeway or major highway, the greater their chances of being diagnosed with asthma.
The researchers reported that they saw a relationship between higher levels of asthma and certain pollutants that come from the burning of fossil fuels — such as the exhaust of cars or trucks — as well as from emissions from industrial plants.
Smoking
The rise in cigarette use by adults during the past century may explain the asthma epidemic in children, according to some researchers. Secondhand tobacco smoke that is inhaled by nonsmokers has a higher concentration of some toxic substances than the smoke inhaled by smokers.
Alert!
Others have looked at the effect of global warming — saying it could impact individuals with asthma because of more carbon dioxide in the air and longer plant growing seasons. These longer growing seasons can mean more pollen in the air, which in turn can trigger more asthma symptoms throughout the year.
Children breathe more air than adults relative to their size and have narrower airways, so secondhand smoke becomes a greater risk factor of asthma in children — and it can increase the severity of their asthma symptoms, the researchers note. In various developing countries where more people are beginning to smoke, a similar pattern of increased cases of childhood asthma is emerging, one study has observed.
