According to a recent US based study it has been found that kids brought up in flats have 45percent more experience to tobacco smoke than the ones who reside in detached houses.

Boffins based of Harvard and Rochester Universities, who did the experiment claimed that the exposure in flats is essentially initiated due to the smoke which sinks in side of the walls and other shared ventilation systems.

Researchers considered samples taken from kids who resided in colony where nobody smokes, and they looked for cotinine - a product of nicotine and a highly receptive marker for tobacco - in their patient's blood.

The study claimed that nearly 73 percent of the 5,000 children who were tested showed high levels of second-hand tobacco smoke.

In all, researchers claimed that nearly 84.5 percent of children who reside in blocks of flats had a cotinine level that sparked of immediate tobacco-smoke exposure, which further was evaluated with 79.6 percent of children who resided in attached households and 70.3 percent who were living in detached houses.

Dr Jonathan Winickoff, study author and associate professor of paediatrics at Harvard Medical School said, "If your neighbours are smoking then you are exposed if you live through the wall in a semi-detached house. In apartment buildings this effect is magnified. Smoke contaminates the whole building. This study is the last link in the chain of evidence. It demonstrates the overwhelming need for smoke-free buildings", added BBC.

Karen Wilson, assistant professor of paediatrics at the University of Rochester Medical Centre, explained that parents try to overprotect kids from dangers, such as tobacco smoke, but in actuality have no control over situations such as second-hand smoke.