Scientists have discovered that ‘third-hand smoke' - leftover cigarette smoke that clings to furniture and walls - may pose a serious health threat, particularly to children.

According to their findings, one compound from this type of smoke appears to damage DNA and is capable of sticking to it in a way that could cause cancer.

This could be especially dangerous for children who place toys or other objects affected by smoke in their mouths.

Dr Bo Hang of the Lawrence Berkeley National Laboratory in the US pointed out that while the idea of third-hand smoke only became a reality in 2009, research since then clearly indicates that it could be detrimental to human health.

"The best argument for instituting a ban on smoking indoors is actually third-hand smoke," he insisted.

He noted that research suggests that many of the 4,000+ compounds found in second-hand smoke can remain indoors long after a cigarette has been put out. These substances may react with pollutants found indoors, such as ozone, to create entirely new compounds. Some of these compounds could cause cancer.

One of these compounds is known as NNA and Dr Hang's studies have shown that this can lock onto DNA causing serious damage and potentially leading to the formation of cancerous tumours.

Confirmation of this could take a long time, however the results of early research have so far been compelling.

Dr Hang emphasised that the biggest risk is for babies and toddlers. Crawling and then putting their hands or toys into their mouths could lead to them swallowing or inhaling third-hand smoke compounds.

He suggested that the best way to get rid of third-hand smoke is to get rid of affected household items, such as sofas, curtains and carpets. Walls should also be sealed and repainted.

For people who cannot replace furniture and fittings, washing and vacuuming items such as sofa covers, bed linen and curtains can also help, he added.

Details of Dr Hang's research were presented at the 247th National Meeting & Exposition of the American Chemical Society in Dallas.