How asbestos causes harm
Asbestos only becomes a health risk when its fibres are released into the air and inhaled. The fibres are microscopic, often 50 to 200 times thinner than a human hair, and invisible to the naked eye. Once inhaled, they can penetrate deep into the lungs where the body struggles to break them down or expel them.
The fibres lodge in lung tissue and the lining of the chest cavity. Over time, the body's inflammatory response to these persistent fibres causes scarring and cellular damage that can eventually lead to serious disease.
Asbestos materials that are in good condition, undisturbed, and properly managed generally do not release fibres. The risk comes when materials are damaged, deteriorating, or disturbed by cutting, drilling, sanding, demolition, or weathering.
Diseases caused by asbestos exposure
There are several diseases linked to asbestos exposure. They are all serious, and most have no cure.
Mesothelioma
Mesothelioma is a cancer of the mesothelium, the thin membrane that lines the chest cavity, abdomen, and other organs. It is almost exclusively caused by asbestos exposure. Australia has one of the highest rates of mesothelioma in the world, a legacy of the country's heavy asbestos use during the 20th century.
Mesothelioma typically develops 20 to 50 years after exposure. It is aggressive and difficult to treat. Even relatively brief or low-level exposure can be sufficient to cause the disease, though risk generally increases with the amount and duration of exposure.
Asbestosis
Asbestosis is a chronic lung condition caused by prolonged inhalation of asbestos fibres. The fibres cause progressive scarring (fibrosis) of the lung tissue, which reduces lung capacity and makes breathing increasingly difficult. It typically develops after sustained occupational exposure over many years.
Symptoms include shortness of breath, a persistent dry cough, and chest tightness. The condition is irreversible and tends to worsen over time.
Lung cancer
Asbestos exposure significantly increases the risk of developing lung cancer. The risk is highest for people with heavy or prolonged exposure, and it is substantially increased for smokers. Someone who both smokes and has been exposed to asbestos faces a risk many times greater than either factor alone.
Pleural disease
Asbestos can cause thickening and scarring of the pleura (the lining around the lungs) without necessarily causing cancer. Pleural plaques are the most common sign of past asbestos exposure. While plaques themselves don't usually cause symptoms, diffuse pleural thickening can restrict lung expansion and cause breathlessness.
The long latency period
One of the most challenging aspects of asbestos-related disease is the latency period. Symptoms typically don't appear until 15 to 40 years after exposure, sometimes longer. This means someone exposed during renovation work in the 1990s might not develop symptoms until the 2020s or 2030s.
This long delay between exposure and illness is part of what makes prevention so important. By the time disease is diagnosed, the exposure happened decades ago and nothing can undo it.
Does the amount of exposure matter?
Yes, but not in a simple or reassuring way. Generally, higher levels of exposure over longer periods carry greater risk. Most asbestos-related diseases historically occurred in workers with heavy occupational exposure: miners, insulation workers, shipbuilders, and construction workers who handled asbestos daily.
However, there is no known safe threshold for asbestos exposure. Cases of mesothelioma have been documented in people with relatively brief or low-level exposure, including family members of asbestos workers who were exposed to fibres carried home on clothing. While such cases are less common, they do occur.
This is why regulations take a precautionary approach and require controls for any work that might release asbestos fibres, regardless of the expected level of exposure.
Occupational vs environmental exposure
Most asbestos-related disease has historically been linked to occupational exposure, where workers regularly handled or disturbed asbestos materials as part of their jobs. Tradespeople, maintenance workers, and demolition crews are among the groups most at risk.
Environmental exposure, from living or working in buildings with deteriorating asbestos materials, carries a lower risk but is not zero risk. Poorly maintained buildings where asbestos materials are crumbling, or buildings where asbestos has been disturbed by amateur renovation, can expose occupants to fibre levels that are cause for concern.
Prevention through proper management
The good news is that asbestos-related disease is entirely preventable. No new exposure means no new disease.
For property managers, this comes down to knowing what's in your building, keeping it in good condition, and making sure any work that could disturb asbestos is handled by qualified professionals. A current asbestos register, a management plan, and clear communication with contractors and maintenance staff are the practical tools that keep people safe.
If you suspect asbestos has been disturbed in your building, an occupational hygienist can conduct air monitoring to assess whether fibre levels are a concern. Where exposure may have occurred, medical advice should be sought.