The facts about second-hand smoke

What is second-hand smoke?  

Second-hand smoke is breathing in someone else’s smoke, and is very dangerous for children.

Second-hand smoke is the mix of two kinds of smoke. One is breathed out by a smoker; the other comes from the burning tip of a cigarette. They mix in the air to make second-hand smoke. The smoke off the tip of the burning cigarette is about 4 times more toxic than mainstream smoke.


 Mainstream smoke   Sidestream smoke

Mainstream smoke (left) and sidestream smoke (right).


Second-hand smoke is very dangerous for children because their lungs are smaller and still developing.

Often children don’t have a choice in whether they are exposed to it, for example in their homes and cars.

Children exposed to second-hand smoke are at higher risk of respiratory infections, asthma, bacterial meningitis and cot death, also known as Sudden Infant Death Syndrome (SIDS).

Smoke spreads around the home and car, even if you open the windows, and bits stick to and build up on surfaces, seats and carpets. Second-hand smoke, and the toxins in it, can reach very high levels in cars because they are small, confined spaces.

Recent New Zealand research found that children exposed to smoking in cars and homes were also more likely to be a smoker later in life. 

Why is second-hand smoke dangerous?

Second-hand smoke is dangerous because it has many chemicals such as:          

  • cyanide
  • carbon monoxide
  • arsenic
  • other bad chemicals

Many of these are poisons or toxins and have been shown to cause cancer. Some of these toxins can also cause:

  • heart disease
  • lung disease
  • stroke


Protect children: don't make them breathe your smoke


Protecting non-smokers from second-hand smoke

The New Zealand Government has committed to a Smokefree Aotearoa by 2025.

The Cancer Society and other tobacco control organisations are working together to achieve this and reduce tobacco harm in our communities.

Together we encourage smokers to quit, encourage health promotion programmes, and support local council regulation.

We’re also asking for national regulation and legislation, such as Smokefree Environments Act.

Current Campaigns working towards a Smokefree Aotearoa are:

How can I help my whānau and local community to become Smokefree?

  • As parents, elders or peers, talk about being Smokefree.
  • Hold Smokefree community events.
  • Make yours a Smokefree car and home.
  • Ask friends, family and whānau to become Smokefree role models and not smoke around the children.
  • Get together and contact your local council telling them your community want Smokefree areas where children are likely to be, such as playgrounds, sports areas, outdoor dining areas, main shopping areas, communal outdoor areas.


Quitline   Smokefree 2025