Even though parents may smoke only outside and away from their infant, babies apparently still absorb dangerous chemicals from them.
Georg Matt, a professor at San Diego State University says up to 90 per cent of the nicotine from cigarette smoke can stick to walls, clothes, hair and skin.
Professor Matt, says his research suggests the chemicals from this 'third hand smoke' can be swallowed, inhaled or absorbed through the skin of non-smokers, putting babies at particular risk.
His study of 49 babies all under 13 months of age, found cotine, a by-product of nicotine, in their urine and hair shafts even when their parents took care to smoke outside the house.
This was seven times higher than levels found in babies with non-smoking parents.
Babies and toddlers can it seems absorb the harmful chemicals simply from touching furniture in a smoker's house, or hugging their mothers after they had a cigarette.
The risks of second-hand smoke are already well-known and babies and children exposed to a smoky atmosphere are twice as likely to have asthma attacks and chest infections, and more likely to need hospital care in their first year of life.
Research also indicates they are also at higher risk of cot death.
Other experts add that babies born to smokers weigh less (about 250g) and because they are smaller than they should be they don't cope with labour as well.