Asthma inhalers can’t do the job if they’re not used correctly. And that’s an issue for many children, according to new research.

“We know from past studies that both parents and children overestimate the ability of children to properly use their inhaler,” said study author Dr Anna Volerman, from the University of Chicago.

The study included 65 pairs of parents and children, ages 8-14, who had asthma and used inhalers. The children went to four Chicago public charter schools. Nine in 10 children were black and most parents were women.

The researchers found that 97% of the children misused their inhaler. Only one child showed mastery, according to the study in the journal Annals of Allergy, Asthma and Immunology.