Why you REALLY shouldn't smoke indoors

Sticky residue left on furniture from cigarette smoke stunts the growth of babies, scientists have warned.

Dubbed third-hand smoke, the yellow stains in homes of tobacco users could also weaken immune systems of newborns - leaving them susceptible to deadly bugs.

Infants are more likely to be at risk to the pollutant because they crawl and put objects in their mouth during their development, experts claim.

But the harm - which could be even worse than second-hand smoke - is completely reversible if the toxic substance is removed, a study has found. 

Despite the effects of both first and second-hand tobacco damage being well known, not much research has been conducted on so-called 'third-hand'.

Red flags were first raised in 2010 when research found that nicotine can react with substances in the air to create carcinogenics.

Scientists from the Lawrence Berkeley National Laboratory decided to confirm the effects by testing on newborn mice who grew up in a contaminated home.

They were exposed to third-hand smoke by having a cotton cloth which had been around nicotine placed in their cages.

The rodents were found to weigh significantly less than those who were brought up in a tobacco-free environment. 

But the effects were completely temporary, according to the study published in the journal Scientific Reports.

Within three weeks of leaving the 'dirty' environment, the mice began putting on weight and catching up with their peers.

Exposure to third-hand smoke led to persistent changes in blood cell counts associated with the immune system. 

It was found there were higher levels of platelets and specific types of white blood cells in the smoke-exposed mice.

These types of white blood cells are associated with inflammation and allergic reactions.

And they were found to be remaining in the blood of the young mice for 14 weeks after the experiment was stopped.   

Dr Antoine Snijders, who was involved in the research, said: 'Third-hand smoke is an underappreciated risk factor in health.

'It's clear that more and bigger studies are needed, particularly in humans, so we can support policy decisions on third hand smoke.' 

Duke University research last month found that second-hand smoke could affect a woman's baby before she has even conceived.

Decades of evidence has shown pregnant women who inhale smoke are more likely to deliver children with brain impairment that affects learning and behavior.

But the study found the risk was identical in lab rats who were exposed to tobacco.

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