(Second and third hand smoking)

Passive smoking is the inhalation of smoke, called second-hand smoke (SHS), or environmental tobacco smoke (ETS), by persons other than the intended “active” smoker. It occurs when tobacco smoke permeates any environment, causing its inhalation by people within that environment.

Being around tobacco smoke is bad for you, even if it’s someone else’s smoke.

When someone smokes a cigarette, most of the smoke doesn’t go into their lungs. It goes into the air, where anyone nearby can breathe it.

Smoking is banned in many public places. But many people are still exposed to secondhand smoke, especially children who live with parents who smoke. Even people who try to be careful about where they light up may not protect those around them

What Is Secondhand Smoke (SHS)?

Secondhand smoke (SHS) is a mixture of 2 forms of smoke that come from burning tobacco:

-Mainstream smoke: The smoke exhaled by a smoker.

-Side stream smoke: Smoke from the lighted end of a cigarette, pipe, or cigar, or tobacco burning in a hookah. This type of smoke has higher concentrations of cancer-causing agents (carcinogens) and is more toxic than mainstream smoke. It also has gases and smaller particles than mainstream smoke. These smaller particles make their way into the lungs and the body’s cells more easily.

When non-smokers are exposed to SHS it’s called involuntary smoking or passive smoking. Non-smokers who breathe in SHS take in nicotine and toxic chemicals the same way smokers do. The more SHS you breathe, the higher the levels of these harmful chemicals in your body.

Among the more than 7,000 chemicals that have been identified in secondhand tobacco smoke, at least 250 are known to be harmful, for example, hydrogen cyanide, carbon monoxide, and ammonia. At least 69 of the toxic chemicals in secondhand tobacco smoke cause cancer. These include the following: Arsenic, Benzene, Beryllium (a toxic metal), Butadiene (a hazardous gas), Cadmium, Chromium (a metallic element), Ethylene oxide, Nickel (a metallic element), Polonium-210 (a radioactive chemical element), Vinyl chloride.

Exposure to secondhand smoke can be measured by testing saliva, urine, or blood to see if it contains cotinine. Cotinine is created when the body breaks down the nicotine found in tobacco smoke.


Second-hand smoke causes many of the same diseases as direct smoking, including cardiovascular diseases, lung cancer, and respiratory diseases. These diseases include:

Cancer: Lung cancer, Breast cancer

Cervical cancer: A 2015 overview of systematic reviews found that exposure to second-hand smoke increased the risk of cervical cancer

Circulatory system: risk of heart disease, reduced heart rate variability

Lung problems: Risk of asthma, risk of chronic obstructive pulmonary disease (COPD)

Mental health: Exposure to secondhand smoke is associated with an increased risk of depressive symptoms.

During pregnancy: Low birth weight, premature birth, worsening of asthma, allergies, and other conditions.

Risk to children

-Sudden infant death syndrome (SIDS), Asthma Lung infections,[ also including more severe illness with bronchiolitis and bronchitis as well as increased risk of developing tuberculosis if exposed to a carrier

-Impaired respiratory function and slowed lungs growth


-Maternal passive smoking increases the risk of non-syndromic orofacial clefts by 50% among their children.

-Learning difficulties, developmental delays, and executive function problemsand neurobehavioral effects. An increase in tooth decay (as well as related salivary biomarkers) has been associated with passive smoking in children

-Increased risk of middle ear infections.

Thirdhand smoke

Thirdhand smoke is generally considered to be residual nicotine and other chemicals left on a variety of indoor surfaces by tobacco smoke. This residue is thought to react with common indoor pollutants to create a toxic mix. This toxic mix of thirdhand smoke contains cancer-causing substances, posing a potential health hazard to nonsmokers who are exposed to it, especially children.

Studies show that thirdhand smoke clings to hair, skin, clothes, furniture, drapes, walls, bedding, carpets, dust, vehicles and other surfaces, even long after smoking has stopped. Infants, children and nonsmoking adults may be at risk of tobacco-related health problems when they inhale, ingest or touch substances containing thirdhand smoke. Thirdhand smoke is a relatively new concept, and researchers are still studying its possible dangers.

Thirdhand smoke residue builds up on surfaces over time and resists normal cleaning. Thirdhand smoke can’t be eliminated by airing out rooms, opening windows, using fans or air conditioners, or confining smoking to only certain areas of a home.

The only way to protect nonsmokers from thirdhand smoke is to create a smoke-free environment, whether that’s your private home or vehicle, or in public places, such as hotels and restaurants.