CHAPTER-I INTRODUCTION
Respiratory disorders, in particular asthma are increasing in prevalence, which is a global
phenomenon. Even though genetic predisposition is one of the factors in children for the increased
prevalence - urbanization, air pollution and environmental tobacco smoke contribute
more significantly. Our hospital based study on 20,000 children under the age of 18
years from 1979,1984,1989,1994 and 1999 in the city of Bangalore showed a prevalence of 9%,
10.5%, and 18.5%, 24.5% and 29.5% respectively. The increased prevalence correlated well with
demographic changes of the city. Further to the hospital study, a school survey in 12 schools on
6550 children in the age group of 6 to 15 years was undertaken for prevalence of asthma
and children were categorized into three groups depending upon the geographical situation of the
school in relation to vehicular traffic and the socioeconomic group of children.
I.I. ASTHMA
Asthma is characterized by apredisposition to chronic inflammation of the lungs in which
the airways (bronchi) are reversibly narrowed. Asthma affects 7% of the population of the United
States, 6.5% of British people and a total of 300 million worldwide. During asthma attacks
(exaceroations of asthma), the smooth muscle cells in the bronchi constrict, the airways become
inflamed and swollen, and breathing becomes difficult. This is often referred to as a tight chest
and is a sign to immediately take medication.Asthma causes 4,000 deaths a year in the United
States. Medicines such as inhaled short-acting beta-2 agonists may be used to treat acute attacks.
Attacks can also be prevented by avoiding triggering factors such as allergens or rapid temperature
changes and through drug treatment such as inhaled corticosteroids and then long-acting beta-2
agonists if necessary. Leukotriene antagonists are less effective than corticosteroids, but have
no side effects. Monoclonal,
