According to epidemiologic studies, about 0.4% of people in Barcelona suffer from severe asthma, with 42.6% experiencing uncontrolled symptoms. A high proportion of these individuals (84.2%) are prescribed systemic corticosteroids. The prevalence data for childhood asthma in Barcelona suggest that air pollution may be a major contributing factor. The city has experienced multiple outbreaks of asthma, resulting in numerous emergency room admissions. In Spain, both asthma and allergies are relatively common, affecting around 5.7% and 11.4% of children under the age of 14, respectively. The incidence of asthma in Spain is low to medium, with recent wheezing and bronchial responsiveness to exercise affecting 4% of the population. Overall, the epidemiology of asthma in Barcelona and Spain as a whole warrants further study and attention.