LITTLE ROCK, Arkansas (Reuters) - A bill awaiting Arkansas Governor Mike Beebe's signature would ban smoking in a vehicle if a child under the age of 14 is present.

That would be an increase from the current age of 6, which has been the law since 2006.

Arkansas is one of four states that have such laws, according to the American Lung Association. California has the strictest. Its law prevents children 18 and under from riding in a vehicle with smoke. Louisiana and Maine have similar laws.

Nearly 60 percent of U.S. children between the ages of 3 and 11 -- almost 22 million children -- are exposed to secondhand smoke, according to a 2006 Surgeon General's report.

"We would certainly hope that states considering these laws would include all children and not just limit them to certain ages," said Erika Sward, director for national advocacy for the American Lung Association.

Opponents of the Arkansas bill argue that it would interfere with parental rights.

(Reporting by Suzi Parker; Editing by Corrie MacLaggan and Jerry Norton)