Introduction

Asbestos is a natural mineral made of fibres that are invisible to the human eye. It was used frequently in construction from around the 1960s, until it was banned in the UK in 1999.^1,2 

It was commonly used in buildings, boilers, pipes, car brakes and as insulation to protect buildings and ships against fire. 

Asbestos related disease refers to a disease or condition caused by exposure to asbestos. This includes;

• Asbestosis (a chronic disease where the lung tissue becomes scarred)
• Mesothelioma (cancer that develops in the outer lining of the lungs) 
• Unharmful chest wall lesions, which are non-cancerous areas of thickened tissue in the outer lining of the lung

These conditions tend to develop around 10-30 years after exposure to asbestos.^2,3,4

Methods of exposure to asbestos

Most people are exposed to asbestos at some point in their life, as low levels of asbestos fibres are often found in water, air and soil. However, asbestos-related diseases only tend to develop in people who have been exposed to asbestos over a long period of time. This prolonged exposure can occur through jobs and occupations, from the environment or through close contact with others who have been exposed.⁵

Occupational exposure

Occupational exposure means that a person is exposed to asbestos through their job and working environment. Occupations at risk of long-term exposure to asbestos include:

• Ship building trades
• Textile manufacturing
• Insulation work
• Construction and buildingFire fightingAsbestos miningMechanics
• Plumbing⁵

Environmental exposure

Asbestos exposure can also occur through the environment, as low levels of asbestos are present in water, air and soil. Houses built before 1999 may contain asbestos, and home renovations, maintenance and DIY projects may lead to asbestos exposure. If asbestos is disturbed, fibres can be released and inhaled, exposing people in the nearby area. People who live close to industrial asbestos sources, such as asbestos mines, are also at risk of long-term asbestos exposure.^5,6

Second-hand exposure

Exposure to asbestos does not only occur through direct contact with the asbestos material itself— you can even be exposed if someone you live with works around asbestos. A person who works with asbestos may carry it home, and fibres may remain in their hair or on their clothes. Other people in the same household may then breathe in the asbestos fibres, putting them at risk of asbestos-related disease, even though they have not been around it directly.⁷ 

How does asbestos-related lung disease occur?

Asbestos-related lung disease occurs quite a long time (approximately 10-30 years) after initial asbestos exposure. It occurs when asbestos fibres are inhaled and then enter the lung. This damages the cells and tissues, and causes inflammation in the lungs. Over time, the lung tissue stiffens and loses its elasticity, eventually causing scarring in the lungs. 

What is asbestosis?

Asbestosis is a long-term, progressive lung condition, caused by the inhalation of asbestos fibres. Asbestosis is a type of interstitial pulmonary fibrosis, which means that it causes scarring of the lung tissue over time, making it harder to breathe.⁸

How does asbestos cause lung tissue damage?

Asbestosis occurs when asbestos fibres are inhaled, enter the lung and are deposited in the tissues, causing cell and tissue damage.

Highly unstable molecules, called reactive oxygen species, react in the lung and cause injury to the cells and tissues.⁸ 

Reactive oxygen species damage Type 1 alveolar cells, which are the cells that line the air spaces in the lungs. Injury to these cells damages the lung, and makes it harder for oxygen to enter the bloodstream.⁸

Asbestos fibres also cause inflammation in the lung, which leads to the activation of fibroblasts. Fibroblasts are cells that produce collagen and connective tissue fibres— they are important in wound healing. 

In asbestosis, these fibroblasts turn into myofibroblasts, and they start producing too much collagen.⁸

This uncontrolled collagen production leads to fibrosis (scarring) in the lung. Over a long period of time, the fibrosis progresses and the lungs become stiffer, making it harder to breathe.⁸

The tissue injury, inflammation and collagen production all lead to scarring of the lungs and asbestosis.

Symptoms, diagnosis and treatment of asbestosis

Symptoms of asbestosis

Symptoms of asbestosis include:

• Shortness of breath
• Persistent dry cough with very little mucus
• Feeling very tired and fatigued
• Wheezing
• Pain in the chest or shoulder
• Chest tightness
• Loss of appetite

People with severe asbestosis may also have swollen fingertips.⁹

How is asbestosis diagnosed?

Determining medical history of patient

If your doctor suspects that you may have asbestosis, they will take a full medical history, including asking about any jobs you have had. This will help them to assess whether you may have been exposed to asbestos. 

Diagnostic tests of lung function 

They will then carry out an examination, and they may request further scans, such as chest X-rays and CT scans, to better understand your condition. 

Your doctor may carry out lung function testing, also known as spirometry — this involves taking a deep breath in, and then exhaling as quickly and forcefully as possible into a small tube, called a spirometer. The spirometer is attached to a monitor, which records the amount of air you breathe out in one second, and the total volume of air you breathe out in one forced breath.¹⁰ 

Interpreting patient results

Asbestosis is a restrictive lung disease. This means that the amount of air you can breathe in is reduced, as the lungs cannot expand fully. This will be reflected in your spirometry results.¹⁰ 

Treatment and management of asbestosis

There is no specific treatment for asbestosis. However, the condition can be controlled with symptom relief, preventative measures, and regular monitoring to see how the condition is progressing.

Symptom relief is the care and treatment given to help reduce and manage the symptoms caused by asbestosis. This may include oxygen therapy, or starting a pulmonary rehabilitation programme to get support with exercising, mental health and nutrition, as well as education about specific lung conditions. 

Preventative measures may include stopping smoking and reducing exposure to asbestos, to prevent worsening of the condition.

Regular monitoring with a healthcare professional is important in order to keep track of how the lung scarring and symptoms caused by asbestosis are progressing over time.

Pleural plaques

Pleural plaques are small, non-cancerous areas of thickened tissue in the outer layer of the lining of the lung, also known as the parietal pleura. They are caused by asbestos exposure.These plaques usually develop approximately 10-30 years after long-term, chronic exposure to asbestos fibres.⁴ 

Pleural plaques develop as asbestos fibres in the lung trigger an immune response and inflammation.This leads to fibrosis and scar tissue formation, as healthy lung tissue is replaced by collagen due to the activation of fibroblasts. This can lead to the formation of small areas of fibrosis (scar tissue) in the parietal pleura, called pleural plaques.⁴ 

These plaques are not a form of cancer, and they are different to asbestosis.⁴

Symptoms of pleural plaques

In most cases, pleural plaques are asymptomatic— this means that they do not cause symptoms. Some people may experience shortness of breath, chest pain and a cough, but this is uncommon.¹¹ 

The asymptomatic nature of pleural plaques means that they are often found incidentally— they may be found unintentionally whilst investigating another condition or symptom.

Diagnosis, management and treatment

Pleural plaques are usually found incidentally on a chest X-ray or CT scan, as they do not tend to cause symptoms. 

If pleural plaques are found on CT or X-ray imaging, they are not usually treated — this is because they are non-cancerous (benign) and do not impact lung function.¹²

Even though pleural plaques are benign and do not require treatment, a diagnosis of pleural plaques may indicate that you are at higher risk of other asbestos-related diseases, such as asbestosis and mesothelioma (a cancer that develops in the outer layer of the lung lining).¹² 

This may require regular monitoring and follow-up in the future.

Prevention

Treatments for asbestos-related lung conditions are limited — therefore, it is better to prevent these diseases from developing by reducing asbestos exposure. 

In workplaces, regulatory measures should be put in place to protect employees from asbestos. This may involve limiting the amount of asbestos an employee can be exposed to, the length of time they can be exposed for, and encouraging employees to wear asbestos masks and respirators. Public awareness and education about the risks of asbestos are also important, so both employers and employees understand the importance of protecting themselves and others.

Regular screening of those who have been exposed to asbestos can help to pick up asbestos-related lung conditions early. Early diagnosis means that people can access the necessary support and advice early, such as pulmonary rehabilitation and help to stop smoking, which will slow the progression of their condition. 

Summary 

Asbestosis (a long-term condition where the lungs become scarred and stiff)³ and pleural plaques (areas of thickened tissue in the lining of the lung)⁴ are both conditions caused by exposure to asbestos. Asbestos is a natural, fibrous mineral that causes extensive damage to the lungs over a long period of time.¹ It is important to remember that both asbestosis and pleural plaques are non-cancerous, although long-term asbestos exposure can increase the risk of developing certain types of cancer, including mesothelioma. Early diagnosis is important in asbestos-related lung diseases, especially asbestosis, as early support, symptom-relief, pulmonary rehabilitation and regular monitoring can help to slow the progression of the disease. However, it is best to prevent asbestos-related lung diseases before they can develop; occupational safety measures and legal regulations are in place to limit asbestos exposure.