Second-hand smoke is the smoke from the lit end of your cigarette and the smoke you breathe out. The particles you breathe out are smaller and 85% of them are invisible and odourless.
There are more than 4,000 toxic chemicals like lead, cyanide, and arsenic in second-hand smoke. 60 of them are carcinogens which are known to cause cancer and mutations in living cells.
A recent Scottish study found that the smoke you breathe out can linger in the air for up to 5 hours. You can't see or smell it but it's there.
This means it will still be there when your kids come home from school.
And because it's made up of particles that are smaller than household dust, it moves easily from room to room, as you move around and open doors.
Watch our film to discover whether it is ever safe to smoke indoors.
Children are more vulnerable to second-hand smoke. They have smaller airways, breathe faster, and their lungs and immune systems are still developing.
Second-hand smoke can affect children of all ages:
Even if you open a window, smoke in a different room or smoke at the open back door it's not enough to protect your kids.
And when you consider the harmful effects that second-hand smoke can have on your child's developing lungs, it's not worth the risk to smoke indoors.
Everyone's situation is different - we can help you find ways to keep your home smoke-free.
Since the introduction of the smoking ban, the biggest source of second-hand smoke for children is at home. The best way to protect your family from the hidden dangers of second-hand smoke is to find ways of quitting or take it right outside.
Find out more about the hidden dangers of second-hand smoke
Or, for help quitting visit www.canstopsmoking.com