Asthma is an inflammation of the respiratory system, which includes the trachea, bronchi and lungs. The symptoms of asthma are highly variable, but it is generally characterized by the obstruction of airflow through the respiratory system. Asthma is extremely common and affects a significant percentage of the world population. There are many possible causes of asthma, but the general treatment for all forms of asthma is inhaling a corticosteroid.
Asthma has a wide range of severity, so its diagnosis must include a clinical classification. Asthma cases have specific severity classifications, including intermittent, mild persistent, moderate persistent and severe persistent. The criteria that physicians use to classify asthma cases include the total frequency of symptoms and the frequency of nighttime symptoms. They also consider the volume of air that the patient expire in one second, known medically as the FEV1. The variability of the FEV1 is another factor in this classification. Physicians also take the frequency of inhalant use into account when classifying asthma.
The frequency of asthma has been increasing since the 1970s, affecting at least seven percent of the world population as of 2010. Developed countries have a much higher prevalence of this condition than the underdeveloped parts of the world. Asthma UK sufferers number about 5.2 million, or about 20 percent of the population. Areas such as Eastern Europe, Ethiopia, India and Indonesia have an asthma prevalence rate of less than three percent.