الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Bronchial asthma is a chronic disease of the airways that is characterized by variable airflow obstruction, bronchial hyperresponsiveness, and underlying inflammation. Childhood asthma is the most prevalent chronic respiratory disease in the western world. In Egypt, The overall prevalence’s of physician-diagnosed asthma was 9.4%, in one study. Although the cause of childhood asthma has not been determined, contemporary research implicates a combination of environmental exposures and inherent biological and genetic vulnerabilities. Environmental pollutants may be inhalants, ingestants or contactants. Inhalalnts include indoor air pollution and outdoor air pollution. Indoor air pollutants include particulate matter, nitrogen dioxide, secondhand smoke, ozone, household cleaning products. Outdoor air pollutants include pollen allergens, diesel exhaust particles, sulfur dioxide, the outdoor air pollution mix. Ingestant allergens include diet and drugs. Contactant allergens include rodent allergens, cockroach allergen, pet allergens, dust mite allergen and molds. Exposure to outdoor air pollutants has been associated with increased airway reactivity, asthma exacerbations, respiratory symptoms, and decreased lung function.