Asthma is a chronic disease marked by inflammation and narrowing of the airways of the lungs, resulting in the symptoms of wheezing, chest tightness, shortness of breath and coughing. The effects of asthma can range from mild discomfort, to severe difficulty breathing, to death from respiratory failure in extreme cases.
More than 20 million Americans have asthma, including more than 6 million children under 18. Asthma is one of the most common chronic illnesses and one with a serious public health impact.
There has been a dramatic increase in asthma cases in both children and adults over the last 30 to 40 years. While the exact cause is unknown, many doctors believe the increase is due to environmental factors.