Passive smoking

Passive smoking, also known as second-hand smoke or environmental tobacco smoke, is when a person breathes in toxic fumes that have remained in the air or surrounding objects after a cigarette has been smoked. It also refers to exposure of unborn babies to their mother’s smoke.

Last Update 07/05/2024

What is passive smoke?


There are three types of passive smoke;

  • Mainstream smoke: breathed in and breathed out by a smoker
  • Side-stream smoke: floating off the end of a lit cigarette
  • Third-hand smoke: smoke that has been absorbed into clothing or furniture

How does passive smoke affect our lungs?


Passive smoke is classed as cancer-causing by the World Health Organization and there are no safe levels of exposure. Passive smoking can cause premature death, disease and disability in adults and children.

In adults: passive smoking is known to cause lung cancer, coughing, wheezing and other illnesses such as coronary heart disease.

In children: passive smoking can increase the severity of asthma symptoms and lead to new asthma cases. It can also cause coughing and wheezing and other illnesses such as middle-ear problems.

There are over 4,000 chemicals generated during the burning and smoking of tobacco products. Of these, over 250 chemicals are known to be toxic or cancer-causing.

Top tips for healthy lungs


Quitting smoking improves the quality and length of your life. Immediately after your last cigarette, your body will feel the benefits.

Stop smoking and:

  • Choose healthy lungs
  • Choose more energy
  • Choose to cough less
  • Choose to feel young
  • Choose better fertility
  • Choose a longer life

Ask your doctor, pharmacist, clinical psychologist, or nurse for help or contact a telephone or internet helpline.

Further information