Smoking

Smoking increases the risk of cardiovascular disease in several ways:

  • Smoking damages the lining of the arteries including the coronary arteries. The damage encourages the build-up of fatty material in the arteries. This can lead to a heart attack or a stroke.
  • Inhalation of carbon monoxide in cigarette smoke reduces the amount of oxygen that can be carried by the blood.
  • The nicotine in cigarette smoke increases the heart rate, putting strain on the heart.
  • Chemicals in cigarette smoke increase the likelihood of the blood clotting resulting in a heart attack or stroke.

Lung disease

Smoking may result in lung diseases.

Sections of a healthy lung and a smoker's lung, showing tar deposits.

A person may develop conditions such as the disease emphysema:

  • the airways become inflamed, and mucus, which normally traps particles in the lungs, builds up
  • infection often occurs in the mucus and alveoli are damaged, reducing their elasticity and surface area
  • the patient becomes breathless, and finds it more and more difficult to obtain the oxygen required for respiration

The damage caused by emphysema is permanent. The disease cannot be cured and can result in death. It is essential that the person seeks medical help to try to prevent progression of the disease.

Lung cancer

The carcinogens in tar in cigarette smoke also cause lung cancer. Almost all cases of lung cancer are caused by smoking.

The vast majority of cases of lung cancer lead to death.

Graph showing cigarettes smoked per male per year since 1900.  The number of cigarettes has risen from approximately 800 to a peak of over 4000 by 1950.  It has since fallen a little.

Note that the trend in the rate of developing lung cancer for women has been increasing, while in men it is decreasing. The main reason is because numbers of female smokers – unlike men – continued to increase in the 1950s and 1960s before starting to fall. Cancer may take some years to develop, so a fall in female rates of lung cancer is likely to occur later. Evidence also suggests that women are more susceptible to developing the condition.

Effects of smoking on babies

For mothers who smoke during pregnancy:

  • smoking increases the risk of miscarriage
  • babies and children are more likely to suffer from respiratory infections and an increased risk of asthma
  • the long-term physical growth and intellectual development of the baby/child is affected
  • there is an increased risk of birth defects
  • the birthweight of the baby is reduced
Graph showing effects of smoking on baby birth weightThe Medical Journal of Australia
Question

The bar chart shows that when mothers smoke, the birthweight of their babies is reduced.

Suggest two pieces of additional information that would need to be collected before drawing firm conclusions about the effect of mothers smoking on the birthweight of babies.

  • Carry out a similar study of mothers of different age groups to see if similar results could be obtained.
  • Check to ensure that other factors – for instance, lifestyle factors of the experimental group – could not have affected birthweight.