Pet Danger: Secondhand and Thirdhand Smoke

Health Professional

If you smoke, you don’t want your spouse, child, close friends, or co-workers exposed to the dangers of the smoke produced when you light up. After all, this is your habit or addiction, not theirs. But did you know that not only can you expose your dog, cat, gerbil, parakeet, and even your pet goldfish to secondhand smoke, but that your pets are also exposed to the residue produced by smoking, i.e., "thirdhand" smoke?

If you are puffing away near your pet, chances are, they are getting regular exposure to secondhand smoke. We know that secondhand smoke exposure in humans is dangerous. Secondhand smoke exposes others to about five percent of what a smoker would get. Kids who are exposed to secondhand smoke can develop chronic obstructive pulmonary disease (COPD), a lifelong restrictive airway disease. They also have double the risk for hospitalization for asthma.

Beyond active smoking and secondhand exposure, there is also thirdhand exposure in environments where regular smoking takes place. Small particulate matter produced as the byproduct of smoke can settle on walls, floors, drapery, stuffed furniture, mattresses, and fabric (like your clothes), as well as in air ducts. Think about where your pet spends most of its time. Dogs and cats often roam the entire house, or spend time in your lap. Their fur can be a magnet for this thirdhand residue. Bird cages, other small animal enclosures, and the water your fish swim in can also harbor this dangerous residue.

Dogs and cats can ingest the residue during self-grooming. There is data to show that certain dog breeds (depending on nose length) are at higher risk of developing nose and lung cancers, while cats who live with heavy smokers (a pack or more a day) are at significantly higher risk of lymphoma. In the case of dogs with longer noses, there is more surface area for the carcinogens to settle, allowing the particles to build up on the surface area of the mucous membranes. Nasal cancers in dogs kill fast. Dogs with shorter noses tend to get lung cancers, because the particles have a shorter distance to travel to the lungs. The most common cancers in dogs due to smoke and smoke byproducts include nasal cavity, sinus, and lung cancers.

Back in 2007, ScienceDaily revealed the dangers of secondhand smoke to pets. It highlighted the constant grooming efforts of cats which could expose them to carcinogens in their fur from the smoke residue particles. Pet birds were also highly susceptible to secondhand smoke because their airways are hypersensitive to pollutants in the air. Birds were at risk of developing pneumonia, lung cancer, and were also at risk of being poisoned because if allowed to fly out of the cage, they typically peck at available cigarette butts, which can cause nicotine poisoning.

The American Veterinary Medical Association recently sounded the alarm (again) on this carcinogenic exposure. The more packs a day smoked by household members, the higher the rates of cancer in pets. A 2005 study in the British Medical Journal found that even when smokers take their smoking habits outdoors, the residue and smoke is not fully removed. The levels of smoke pollutants in a smoker’s home was still, on average, five to seven times higher than non-smoking households.

E-cigarettes, hookahs, cigars, and pipes also emit smoke, even if they don’t all contain tobacco. Vaping smoke still contains dangerous particulate matter (nicotine in some cases) and can also pose a secondhand or thirdhand problem to humans and pets — not to mention the danger of a pet ingesting the contents of vape cartridges.

By the time your pet shows frank symptoms of exposure to secondhand or thirdhand smoke, irreversible damage to their lungs or cancers may have developed. Pets offer owners unconditional love. In return, they deserve a safe home environment. It’s impossible to control all pollutants and contaminants, but eliminating cigarette smoke and residue will most assuredly reduce the risk of lung diseases and certain cancers. If protecting your own health is not enough motivation, then consider quitting for the sake of your devoted, innocent pets.

Some quick tips to limit thirdhand smoke residue:

  • Quit or limit smoking. Do it mostly outdoors away from your home.
  • Avoid smoking in your car.
  • Shampoo carpets and wash floors on a regular basis.
  • Wipe down surfaces, including walls (when possible) and use fabric cleaners on upholstered goods (use biodegradable cleaners).
  • Change and wash clothes daily.
  • Regularly shampoo dogs and cats and rinse them down per your veterinarian’s recommendations.
  • Wash down bird cages regularly and clean fish bowls and tanks on a regular basis.
  • Keep pet food supplies and utensils separate from the smoking environment.

See More Helpful Articles:

Secondhand Smoke is a Danger to Kids

The Dangers of Thirdhand Smoke


Eli Hendel, M.D. is a board-certified Internist and pulmonary specialist with board certification in Sleep Medicine. He is an Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations. His areas of expertise in private practice include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases.