What's more, finding evidence of nicotine, a chemical in tobacco, in children's saliva was a better predictor of whether they would need to come back to the hospital, compared to the information parents gave to doctors.
"We think saliva is a good and potentially useful test for assessing an important trigger for asthma," Dr. Robert Kahn, the study's senior author, told Reuters Health.
Previous research has found that being exposed to tobacco can lead to airway problems and poor asthma control among children, Kahn and his colleagues write in the journal Pediatrics.
By figuring out which children are being exposed to tobacco, doctors may be able to step in and identify and possibly eliminate the exposure, said Kahn, a pediatrician at Cincinnati Children's Hospital Medical Center in Ohio.
For example, if a parent is still smoking cigarettes and exposing the child to smoke, doctors can offer the parent smoking cessation tools while the child is hospitalized.
For the new study, the researchers assessed data from 619 children admitted to Cincinnati Children's Hospital Medical Center for asthma or other breathing problems between August 2010 and October 2011. The children were between one and 16 years old.
Image: Asthmatic child, via Shutterstock