A tobacco researcher says you could be harming your children’s health if you’re smoking, even when they’re not around.

“Whereas secondhand smoke is inhaling smoke from a lit tobacco product, thirdhand smoke is inhaling, ingesting, or dermally absorbing the secondhand smoke pollutants,” University of Cincinnati tobacco researcher Ashley Merianos said.

Thirdhand smoke can be found on furniture, decor, walls, and floors. It can cause cancer and respiratory problems.

“Thirdhand smoke pollutants can include well-known nicotine, as well as cancer causing chemicals such as tobacco-specific nitrosamines,” Merianos said. “In our study, we looked at one called NNK, which is the most potent known human carcinogen found in tobacco smoke." 

The University of Cincinnati found that 50% of kids living in homes with a smoker had NNK on their home services, and 70% had NNK found in dust throughout their homes.

“We also found that 100% of children had nicotine detected on their surfaces, and about 100% had nicotine detected in dust,” Merianos said.

These toxins were found in homes with smoking bans, and in places where people were not allowed to smoke around children.

“We have found that thirdhand smoke can last in environments for up to years," Merianos said.

This means your child could be exposed, and you wouldn't even know it.

The study also found that children living in lower-income households had higher levels of NNK and nicotine in their homes.

Health experts want parents and grandparents to be aware that not smoking inside the house is not enough, as it doesn't fully protect kids from the dangers of the toxic chemicals found in cigarettes.

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