Convince your squad to quit. Even "third-hand smoke" left on walls and carpets is toxic.

I'm a repentant ex-smoker. Pack-a-day at the peak of my addiction, beard like a fragrant ashtray. Christ knows what damage I've done to myself. Pretty gross, really. Note though, I was always expressly mindful of the well-documented ills of second-hand smoke and never lit up in my own home, let alone anybody else's. But as conscientious as I was to take my habit outside and never too close to people without their express permission, it turns out my smoky beard and clothes may still have held significant toxicity for those that came into contact with them. Even well after each ciggie fix.

New research suggests that "third-hand smoke" may pose serious health risks to non-smokers. If you're unclear on the definition of third-hand smoke, a term coined in part by Dr Jonathan Winickoff, it's the unfavourable remnants of fumes left behind on inanimate objects. Don't scoff just yet. Smoke residue clings to clothing, carpets, furniture (and likely my beard hair) resulting in a noxious build up of toxins that science says can harm animals who come in contact with any and all of those things. It certainly harms mice (who, remember, share about 99% of our genetic make up - making them so popular with the health science kids).

A recent study had a team of researchers, lead by Dr. Manuela Martins-Green at the University of California, Riverside, expose household textile mainstays like carpets, curtains and upholstery to the approximate smoke levels found in a typical smoker's home. Once the standard stew of nocuous toxins had settled and stockpiled themselves onto the seemingly harmless surfaces, healthy mice were brought into contact with them. They did not fare well.

Caged mice exposed to residue rich fabrics showed a 50 per cent increase in inflammatory molecules in their liver and blood after just one month. After two months living with smoky fabric, proper cell damage to both brain and liver was found in tissue samples. Four months into the study, mice cortisol levels shot up by 45 per cent - enfeebled immune systems and weight gain are just a couple hallmarks of excess cortisol. The mice also experienced an unwholesome 30 per cent spike in blood glucose and insulin levels, two markers that point to a higher risk of diabetes. At six months, levels for all of these were even higher.

If you're a little freaked out after reading about the effects of third-hand smoke on mouse organs, consider that Dr. Taylor Hays at the Mayo Clinic in Rochester, Minnesota offers some calming counsel. "It's important to note that a one-off or casual exposure is not going to have measurable impact on people." To be sure, clunkily applying data derived from mice to humans is not the most scientific approach and more investigation into the effects of third-hand smoke on humans is needed. That said, we already know that there is no such thing as a healthy amount of cigarette smoke. Sorry, but that's categorical.

Some experts like Martins-Green maintain that third-hand smoke is easily as damaging as first and second-hand smoke. Kids in particular are at considerable risk even when parents think they're being careful. "Cotton shirts are a terrible sink - a parent goes outside to smoke, but then crawls into bed and reads a book to their kid." The case for quitting reinforced. Or frequently changing your clothes like you're an Oscar presenter.       

Winickoff echoes Martins-Green. He says that because kids breathe faster and interact with household surfaces more frequently it could potential up their exposure by 20 times that of adults. The real stinker he says is that third hand smoke is not so easy to escape. It's particularly resistant to removal, even with industrial grade cleansing agents. "In order to get rid of it in the wallboards, you have to get rid of the wallboards." Often it's a stale residue you can smell - non-smokers usually know immediately when they're visiting a smoker's home.

My preachy two-cents to smokers, for what it's worth, is to just keep quitting. I read Alan Carr's famous book on quitting but only after quitting three times and lighting up again every time. Even if it takes 3 or 5 or 10 tries, eventually it'll stick and you will never regret getting free of it. My completely non-scientific advice to friends and family of smokers is to continue to lovingly (and only very occasionally) nudge them in a direction that has them think about quitting. But definitely have them smoke outdoors, and maybe suggest they change into something less smoky before a cuddle. Feel free to invoke this study and #mouseorgans if they balk.