Skip to main content

The risk

Smoking harms nearly every organ in the body, from the heart and blood vessels, to the lungs and respiratory system, immune system, reproductive organs, digestive organs, bones and other organs.

With every cigarette smoked, around 7,000 chemicals are inhaled. The chemicals in cigarettes are toxic to the body and include:

  • Carbon monoxide – a poisonous gas found in car exhaust fumes that reduces the amount of oxygen being carried around the body
  • Nicotine – an addictive chemical that increases heart rate and blood pressure
  • Ammonia – normally used in chemical cleaners to remove dirt
  • Tar – a toxic chemical containing cancer-causing substances that forms a sticky brown residue inside the lungs. Over two thirds of the tar in each cigarette smoked remains in the lungs.

Smoking and cardiovascular disease

The inhaled chemicals from cigarettes enter the bloodstream and make the walls of the arteries sticky, increasing the number of fatty deposits (known as plaques) that stick to the artery walls and build up over time. This build-up of plaques is also known as atherosclerosis – the main underlying cause of cardiovascular disease.

As the artery walls become narrowed by atherosclerosis, it becomes harder for blood to travel through them to carry essential oxygen to the heart, brain and other parts of the body. If a main artery to the heart is blocked, this can result in a heart attack. If an artery to the brain is blocked, this can cause a stroke. Blockages in arteries in the limbs can cause peripheral artery disease.

Secondhand (passive) smoking can also cause harm.

The impact

Life expectancy is reduced by ten years on average for smokers who continue smoking.

Smok­ing caus­es around 5,000 deaths in NZ every year through can­cer and car­dio­vas­cu­lar dis­eases like stroke.

The risk of heart attack is up to four times greater and the risk of stroke up to two times greater for smokers.

However, giving up smoking can almost immediately improve health as well as decrease some of these risks, and health benefits continue to build over the non-smoking period.

  • In just 20 minutes of giving up smoking, resting heart rate (a key indicator of overall fitness) will reduce.
  • After 12 hours, carbon monoxide levels in the blood will have dropped significantly, and oxygen levels will have improved.
  • In less than three months, the risk of heart attack drops and lung function improves.
  • In just one year, the risk of coronary heart disease is half that of someone who continues to smoke.
  • And after 15 years, the risk of coronary heart disease and death is approximately the same as for someone who has never smoked. It is never too late to quit smoking.

What is HRI doing?

The Clinical Research Group focuses on the prevention of atherosclerosis in children and young adults with risk factors for early heart disease, especially for those who are obese, exposed to passive smoke in the home, smoke themselves or have high levels of cholesterol. Early detection and prevention of advanced heart disease may save hundreds of thousands of lives each year.


  1. Ministry of Health. (2004). Looking upstream: Causes of death cross-classified by risk and condition, New Zealand 1997. Wellington: Ministry of Health.


Every donation to the Heart Research Institute is an investment into the lives of millions.

Help us to make a long-lasting difference by donating now.

Other ways you can help