Scientists have not been able to determine a definitive cause for the increase. The bronchial tubes of asthma sufferers are almost continuously inflamed and hyperactive, sent into suffocating spasms by a broad range of provocations that may vary from on individual to another. An attack finds the victim gasping for breath as the airways become constricted, the passages inflamed and clogged with thick, sticky secretions. People infrequently outgrow the condition entirely. The occurrence of childhood asthma is three times as high in Puerto Rican children as compared to Non-Hispanic White children.
Severity also varies from group to group.
Black children are three times as likely as Whites to be hospitalized for treatment of asthma. And that number tells only part of the story. The findings of a 1997 Detroit study show that Black children were likely to have more severe disease than White children of the same socioeconomic status. This indicates that race per se may play a significant role in asthma's prevalence. Since a hereditary component of asthma is generally accepted, the idea that heredity is involved in the high prevalence of asthma in minority groups is not unreasonable.