Dangers of second-hand smoke

Breathing in other people’s smoke is known as exposure to second-hand smoke or passive smoking. When you smoke, it’s not just your health that’s put at risk, but the health of anyone around you.

Most second-hand smoke comes from the tip of a burning cigarette. This makes it almost impossible to direct smoke away from those around you.

If you only smoke in one area of your home the harmful chemicals will spread rapidly from room to room and can linger for up to 5 hours.

If you smoke in a confined space such as a car, you’re exposing your fellow passengers to even more harmful chemicals. This is why smoking in cars with children on board has been banned in Scotland since December 2016.

Risks to other people

People exposed to second-hand smoke face the same dangers as smokers themselves. They too inhale the same poisonous gases and thousands of toxic chemicals found in tobacco smoke. Their risk of developing smoking-related diseases will also increase.

Pregnant women exposed to second-hand smoke will pass on harmful chemicals to their babies. Second-hand smoke is also particularly harmful for children, and others with long-term heart and/or breathing conditions.

Short-term effects

Some short-term effects from exposure to second-hand smoke include:

  • coughing
  • headaches
  • eye and nasal irritation
  • sore throat

Long-term effects

Long-term effects from exposure to second-hand smoke include increased risk of:

  • coronary heart disease (risk increased by 25-30%)
  • lung cancer (risk increased by 20-30%) and other cancers
  • stroke (risk increased by 20-30%)
  • increased risk of chronic obstructive pulmonary disease (COPD) and other breathing problems

Breathing in second-hand smoke makes the blood stickier, meaning there is an increased risk of blood clots forming, even with brief exposure. A blood clot can block an artery and cause:

  • heart attacks
  • strokes
  • angina
  • complete heart failure

In pregnant women exposed to second-hand smoke, there is an increased risk of complications during the pregnancy and after the birth. The most likely risk is that your baby could weigh less than expected.

Risks to children

Children breathe faster than adults, which means they take in more of the harmful chemicals in second-hand smoke. They’re even more sensitive to smoke than adults because their bodies are young and still developing.

Research shows that babies and children exposed to a smoky atmosphere are likely to have increased risk of:

  • breathing problems, illnesses and infections
  • reduced lung function
  • wheezing illnesses and asthma
  • sudden and unexpected death in infancy (SUDI)
  • certain ear, nose and throat problems, in particular middle ear disease

There is also an increased risk of developing:

  • bacterial meningitis
  • bronchitis
  • pneumonia
  • acute respiratory illnesses

Risks to pets

Second-hand smoke can be damaging to pets health too.

Family pets are at a high risk of disease and illness due to second-hand smoke. This can result in higher vet costs and emotional distress on families.

Over 7,000 harmful chemicals are found in smoke, with 70 known to directly cause cancer. These pose a threat to all kinds of pets including dogs, cats, birds, guinea pigs and even fish.

There are small steps you can take to reduce harm from exposure to second-hand smoke.


  • smoke outside – this won’t completely protect our pets but it will reduce the risk
  • clean and steam carpets regularly to reduce the toxic particles at home


  • do not leave cigarette butts or ashtrays in easy access of pets

Quit Your Way can also provide you with support to quit.

Take it Right Outside

Visit our Take it Right Outside campaign for quizzes, hints and tips on second-hand smoke.

Last updated:
20 December 2022

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