Causes of asbestosis

Asbestosis is caused by breathing in asbestos fibres. Certain trades are more likely to have been exposed to asbestos in the past.

Asbestos fibres

When you inhale a foreign body, such as a dust particle, cells called macrophages (found in the alveoli) usually hunt and break the particle down before it gets into your lung tissues and blood stream.

However, asbestos fibres are too tough for the macrophages to break down. In an attempt to break down the asbestos fibres, the macrophages release substances to destroy the fibres. These substances can permanently damage the tiny air sacs in your lungs, known as alveoli.


When you breathe in, the alveoli help to transfer oxygen from your lungs into your blood. When you breathe out, the alveoli help to transfer carbon dioxide out of your blood, through your lungs and out of your mouth.

If you are exposed to asbestos fibres for a long period of time, the alveoli can become more severely damaged and scarred. The scarring is known as fibrosis. Fibrosis of the alveoli caused by large amounts of asbestos is known as asbestosis.

If the alveoli are scarred, your ability to inhale oxygen and exhale carbon dioxide will be affected, resulting in breathlessness.

Occupations associated with asbestos exposure

The use of asbestos increased significantly after World War II. It peaked during the 1970s before declining during the 1980s and 1990s. You may have been exposed to asbestos if you worked in an industry such as building or construction, where asbestos was used during this time period.

Occupations particularly associated with exposure to asbestos include:

  • insulation workers
  • boilermakers
  • plumbers, pipefitters and steamfitters
  • shipyard workers
  • sheet metal workers
  • plasterers
  • chemical technicians 
  • heating, air-conditioning and refrigeration mechanics

Industries known to have used asbestos during these times include:

  • construction
  • shipbuilding and repair
  • chemical manufacturing
  • non-metallic mineral stone production
  • railways
  • yarn, thread and fabric mills
  • rubber and plastic production
  • trucking services

Other factors

How asbestos affects individuals can also depend on other factors, including:

  • the type of asbestos fibre they were exposed to – blue asbestos is more dangerous than brown asbestos, and both blue and brown asbestos are much more dangerous than white asbestos
  • how much asbestos was breathed in
  • the individual’s health – for example, symptoms are likely to be more severe in people who smoked or had lung disease before being exposed to asbestos

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