Secondhand smoke is also described as passive smoke or environmental tobacco smoke (ETS). Though most of us ignore it, you should know that it is dangerous and constant exposure to it can cause diseases and in extreme cases, even death. Statistics and facts about secondhand smoke need to be publicized because of their alarming proportions. Having said that, let us see what this supposedly “innocuous” thing really is.


The Surgeon General’s report uses the term “involuntary smoke” to describe secondhand smoke.

This is the smoke that is exhaled by the smoker and the smoke that emanates from burning tobacco such as a burning cigarette, a burning cigar or a burning pipe. It is also referred to as the environmental tobacco smoke (ETS).

It is not to be confused with cigarette smoke, which is the smoke that is inhaled by the smoker when smoking.

The person who smokes the cigarette or the cigar or the pipe is the active smoker. The person within his vicinity who inhales the smoke exhaled by the active smoker is called the secondhand smoker or the passive smoker.

It happens when the tobacco smoke from the smoker spreads into the surrounding, polluting the environment and causing people in the vicinity to inhale it.

Such exposure to this type of smoke can cause disease, disability, and even death. This is the reason why smoking is banned in public places and workplaces to protect the non-smoking population.

If you work at a place where smoking is allowed, you will be continuously exposed to smoke puffed out by the smokers.

While the smoker exposes him to the dangerous effects of smoking, he also puts you at considerable risk

According to the US Surgeon General report of 2006, nonsmokers are at a 25 to 30 percent higher risk of developing heart disease and 20 to 30 percent higher risk of developing lung cancer when exposed to tobacco smoke.

The Environmental Protection Agency (EPA) classifies secondhand smoke as a Group A carcinogen type, meaning, it is a substance that is known to cause cancer in humans.

It also means that you, a nonsmoker, are at a cancer risk that equals that of a habitual smoker.

Group A carcinogens do not have any safe level standards. Even a little exposure can cause changes in the passive smoker’s blood, making blood platelets stickier, damaging the blood vessel lining, and increasing the heart rate.

This greatly increases your risk of heart attack, especially if you are already a high-risk individual.

Harmful contents of secondhand smoke

According to The National Toxicology Program, from more than 4000 chemicals present in secondhand smoke. Of these, more than 250 are known to be toxic and have a disease-causing potential such as hydrogen cyanide, carbon monoxide, and ammonia. Of these, more than 50 are carcinogenic. A small list of such chemicals is given below.

At least 69 of the toxic chemicals in secondhand tobacco smoke have a cancer-developing potential. These include:

(Arranged alphabetically)

  • Arsenic
  • Benzene
  • Beryllium
  • 1,3–Butadiene
  • Cadmium
  • Chromium
  • Ethylene oxide
  • Nickel
  • Polonium-210
  • Vinyl chloride
  • Formaldehyde
  • Benzopyrene
  • Toluene

Passive smoker

The smoker has his causes to smoke but the passive smoker doesn’t and is a victim of the smoker’s vice.

The smoker’s exhaled smoke, when inhaled involuntarily by any nonsmoking person, comes to be called as secondhand smoking, passive smoking or involuntary smoking. And the nonsmoker who inhales such smoke is called a secondhand smoker.

Secondhand smoke is a dangerous pollutant of the air, which can have harmful effects on the health of the secondhand smoker.

The quantum of such smoke emitted varies on the amount of tobacco that is burning.

For example, secondhand smoke emitted from a burning cigar is equal to the smoke emitted from smoking one pack of cigarettes.

This makes smoke from a cigar more dangerous than that from a cigarette. Therefore, passive smoking from cigar smoke is more dangerous than cigarette smoke due to its higher tobacco content.


  • Mainstream smoke. This is the smoke that is exhaled by the smoker. Exhaled mainstream smoke contains between 15 and 43 percent of the particulate matter in secondhand tobacco smoke.
  • Side-stream smoke. This is the smoke that emanates from burning tobacco. In other words, it is the smoke that is emitted from a burning end of a cigarette, cigar or pipe that is held in the hand or kept lit on the ashtray. Since sidestream second-hand smoke is generated at lower temperatures than mainstream smoke, it contains a higher concentration of toxins. It is the main constituent of secondhand smoke, providing most of the vapor phase and over half the particulate matter. Sidestream smoke differs in chemical composition because it is produced at a lower temperature and higher alkalinity than mainstream smoke.

Common places of exposure 

Secondhand smoking or passive smoking by nonsmokers is seen occurring most commonly in the following places.

  • Homes
  • Workplaces
  • Cars
  • Bars and restaurants
  • An enclosed party hall
  • Or even an open space if the smoker is close by

Safe time limits for exposure to secondhand smoke

The Surgeon General’s report concludes that there are no such established safe limits for passive smoking.

Even a little exposure to secondhand smoke can cause harm and limit the flexibility of the arteries in the body of the passive smoker.

It is said that even 30 seconds of secondhand smoking can increase your risk to the several effects. Of course, the risk increases with the time of exposure.

Distance and reach of secondhand smoke

Secondhand smoke travels up to a distance of 20 feet in either direction in the atmosphere. It can seep through small openings, through gaps of shut doors and windows, through ventilation and air conditioning ducts.

Protection from secondhand smoke

According to the Surgeon General’s report, the only way to ensure protection from secondhand smoke is to ban smoking in closed and indoor areas. No amount of ventilation or cleaning will eliminate the risk of such smoke.

The Surgeon General has concluded that the only way to fully protect yourself and your loved ones from secondhand smoke is through totally smoke-free environments.

Opening a window for ventilation, air conditioning, or an exhaust fan cannot eliminate this smoke’s exposure.

Measuring secondhand smoke in your home or workplace

Secondhand smoking exposure can be measured by testing the air indoors for the concentration of chemicals of secondhand smoke such as:

  • Toxic airborne gases such as nicotine, arsenic, carbon monoxide and cyanide. Air nicotine monitoring can be done using a passive air nicotine monitor, which contains a filter. Laboratory analysis then determines that amount of nicotine collected
  • Particles less than 2.5 microns in diameter, which are capable of penetrating deep into the lungs. TSI AM 510 SidePak Personal Aerosol Monitor is used to measure suspended particles that can be inhaled.

Measuring secondhand smoke in you

Blood, saliva, hair, toenails, and urine of the passive smoker can be tested for the presence of carbon monoxide, cotinine and other chemicals and gases. Cotinine is the substance that is formed after nicotine is broken down in the body.

Hair biomonitoring measures nicotine concentrations in the hair. Saliva Biomonitoring measures cotinine in the saliva for short-term exposure.