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Asthma and Allergens

Asthma is a chronic disease that affects the airways carrying air into and out of the lungs. During an asthma attack airways become inflamed making them sensitive and likely to react strongly to irritants or triggers. When irritated the airways become narrower restricting the amount of air that flows to lung tissue. Restricted airflow causes symptoms like wheezing, coughing, chest tightness and trouble breathing.

Risk Factors

The major predisposing genetic factor for asthma is atopy, or the tendency to produce abnormal amounts of IgE antibody in response to triggers. Genetically susceptible individuals exposed to environmental allergens experience sensitizing events involved in the development of asthma. The timing of the exposure increasingly appears to be critical to gene expression, and recent studies suggest that some sensitizing events actually can occur in utero.

After sensitization, an atopic individual is predisposed to allergic inflammation and asthma exacerbation related to repeated exposures to the same allergen. Contributing factors such as small birth weight, lifestyle choices, maternal smoking, and access to medical care may also influence the likelihood of developing asthma upon exposure to environmental risk factors.

Scope of the Issue

As our understanding of the mechanisms and physiology associated with childhood asthma and allergies has grown, so have the number of effective control and treatment strategies. Even with these advances, asthma cases are increasing. An estimated 23.2 million Americans suffer from asthma, almost 9 million of whom are under the age of 18. Asthma is the leading chronic illness of children in the United States and the leading cause of school absenteeism due to chronic illness.

Numerous studies highlight the unequal impact of asthma and allergies on specific subsets of the population, including minorities and poor families, as well as people living in urban environments. Studies differ on the degree to which race and income affect risk level. Given the difference in findings, race and poverty persist at least as potential predictive categories in assessing risk of asthma.