A consultation has been launched to consider a ban on smoking in cars where children are present.
The move has been welcomed by health campaigners who are urging ministers to put the restrictions in place before the next parliament.
Children who are present to cigarette smoke in cars are exposed to dangerous levels of toxic fumes, says charity Action on Smoking and Health (Ash).
The consultation document states that se cond-hand smoke is a "real and substantial threat" to child health".
And it points out that many under-18s in England report being subjected to second-hand smoke in private vehicles such as the family car.
It adds: "The aims of these proposed regulations on smoking in private vehicles carrying children would be to: protect children from the health harms associated with exposure to second-hand smoke in private vehicles; encourage action by smokers to protect children from second-hand smoke; and in time, lead to a reduction in health conditions in children caused by exposure to second-hand smoke."
The consultation, which will seek opinions on draft regulations before they come into force, is expected to run for six weeks.
Earlier this year MPs voted in favour of legislation that would enforce a ban on smoking in cars with children as part of the Children and Families Act.
Copyright Press Association 2014