New research suggests that hospitalization doubles for kids with asthma who are exposed to secondhand smoking.

"The results of this review serve as a reminder to parents of just how dangerous it is to expose their children to secondhand smoke," Avni Joshi, senior author and pediatric allergist and immunologist at Mayo Clinic Children's Center, said in a statement. "We knew that kids should not be exposed to tobacco, but how bad their asthma is likely to be with tobacco exposure was not clear. This study helped us quantify that risk, and so it informs as well as empowers us with the risk assessment. A child is twice as likely to end up in the hospital with an asthma flare if family members continue to smoke."

Researchers led by Mayo Clinic Children's Research Center did a review of 25 studies looking at smoking exposure at home. More than 430,000 children were included in the review, with a mean age of 7.6 years. The majority of the studies -- 96 percent -- investigated smoking exposure at home.

"The study also illustrates the increased burden of disease on the health care system with increased rates of hospitalization," Joshi said. "The children are missing school if they are hospitalized, and the parents miss work. It is a big financial burden for the family, as well as for society. A child being hospitalized has a high risk of hospital-acquired infection, so I think this is fairly serious."

The study drives home the point for parents that, if your child is twice as likely to be hospitalized, you should make some changes in your life and try to quit smoking.

The findings are detailed in the journal Annals of Allergy, Asthma and Immunology.