Causes of asbestosis

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

What is asbestos?

Asbestos is a general termfor a group of minerals made of microscopic fibres.Materials containing asbestos used to be widely used in construction, because they are strong, durable and fire-resistant.

There were three main types of asbestos in commercial use:

• crocidolite ("blue asbestos")
• amosite ("brown asbestos")
• chrysotile ("white asbestos")

All these types of asbestos are hazardous if a material containing them becomes damaged and the fibres are released into the air.

No crocidolite was imported into the UK after 1970, and both amosite and crocidolite were banned in 1985 (although voluntary bans on the industrial use of both these materials came into force earlier than this). Chrysotile was not banned until 1999.

This means that, although asbestos is no longer used, materials containing asbestos are still found in many older buildings.

How asbestos fibres affect the lungs

When you inhale a foreign body, such as a dust particle, cells in the lungs called macrophagesusually hunt and break the particle down before it gets into your lung tissues and bloodstream.

However, asbestos fibres are too difficult for the macrophages to break down. In an attempt to break down the fibres, the macrophages release substances that are intended to destroy the fibres, but actually cause the tiny air sacs in your lungs (alveoli) to become damaged and permanently scarred over time. This scarring is what is known as asbestosis.

Alveoli are crucial in transferring oxygen from the air into your bloodstream and removing carbon dioxide from your bloodstream. If they become damaged and scarred, these processes will be affected, resulting in symptoms such as breathlessness.

For asbestosis to develop, prolonged exposureusually over many yearsto relatively high numbers ofasbestosis fibres is necessary.

Occupations associated with asbestos exposure

The use of asbestos increased significantly after World War II. Itpeaked 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 during this periodinclude:

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

Now that asbestos isno longer used,those most at risk of being exposed to asbestos fibres include people whose jobs put them at risk of damaging any asbestos remaining in older buildings, such as caretakers,electricians and demolition workers.

TheHealth and Safety Executive (HSE) website has more information about when you are most likely to be at risk of asbestos exposure.