Can secondhand smoke harm my pets?

Not surprisingly, the answer is yes. 
Tobacco smoke contains more than 4,000 chemical compounds, 43 of which are known to be carcinogens. While many studies have shown that exposure to these chemicals can increase people's chances of heart disease, lung cancer, and other cancers, some recent studies have shown that these chemicals also increase the risk of these diseases to pets.

Research performed at Colorado State University has documented that environmental tobacco smoke has a clear effect on dogs and their chance of falling victim to disease. Studies have shown that the more people smoke in a household, the higher their dogs' risk of developing certain kinds of cancer. Dogs with long noses are at an even greater risk of developing certain nasal and sinus cancer, as they expose more tissue to the carcinogens when they inhale. 

CSU's research has also shown that the effects of exposure to secondhand smoke are lasting. Chemicals from cigarette smoke can be found in animals' bodies for a long period of time. In fact, measurable levels of carcinogens can be found in dogs' hair and urine for months after exposure.

Another study by Tufts University showed that cats exposed to secondhand smoke have an increased chance of developing a type of oral cancer commonly found in smokers--called squamous cell carcinoma--possibly because the carcinogens in smoke can settle on cats' fur and cats can pick them up as they groom themselves.

Even if they don't develop cancer, pets can have strong reactions to smoke particles in the air. Just like their human families, pets can develop respiratory infections, lung inflammation, and asthma when exposed to secondhand smoke.