People with asthma suffer from recurrent attacks of breathlessness and wheezing, which vary in severity and frequency. Some people experience symptoms more frequently during physical activity or at night, while others experience them intermittently. During an asthma attack, the bronchial tubes' lining swells, narrowing the airways and reducing the flow of air.
There is a high rate of sleeplessness, fatigue during the day, reduced activity levels, and school and work absences associated with recurrent asthma symptoms. The mortality rate of asthma is relatively low compared to other chronic diseases.
The World Health Organization estimates that 235 million people suffer from asthma.