Asbestos diseases result from the inhalation of asbestos fibers into the airways and the lung. Once airborne, asbestos fibers can remain in the air and be breathed for hours. The processes of mining, milling, and manufacturing, and cutting or moving an asbestos-containing product can all disturb fibers and cause them to linger in the air.
Once inhaled, larger asbestos fibers are deposited in the nose and upper airway. Smaller fibers can penetrate deeper into the lung. Once lodged in the lung, the fibers provoke an accumulation of macrophages, which are cells in the immune system that exist to absorb foreign particles in the body. Macrophages are not able to absorb asbestos fibers and scar tissue forms. Over time, the accumulation of fibers and scar tissue can lead to asbestos diseases.
Lung tissue is very thin and consists of millions of air sacs surrounded by blood vessels and connective tissue. The part of the lung surrounding the air sacs is called the interstitium. If scarring occurs in the interstitium it is called interstitial fibrosis. If thin asbestos fibers are inhaled and get into the interstitium they can be a cause of interstitial fibrosis. Interstitial fibrosis from inhaled asbestos is called asbestosis. Interstitial fibrosis can occur from many products and diseases. Asbestosis is interstitial fibrosis specifically due to inhaled asbestos.
The pleura is the thin membrane covering the lungs and lining the inside of the chest walls. When the pleura is irritated, it results in inflammation. In some cases pleural effusion occurs, causing a collection of fluids to accumulate in the pleural space. Adhesions can form, causing the pleural layers to stick together. The symptoms include a sharp chest pain that will move to the tip of the shoulder on the side that is affected. Even though the pain will be continuous it will be much worse when breathing or coughing. Pain from this condition is caused when the two inflamed membranes rub across each other. Pleural plaques and pleural fibrosis result in scarring in the outside lining of the lung, called the pleura or pleural membranes. When visible on a chest x-ray, this scarring is termed pleural plaques or pleural fibrosis. Other conditions can cause pleural scarring; however, pleural plaques and fibrosis on a chest x-ray can be attributed to asbestos if there is a history of exposure and no other cause is evident. Pleural effusion – a collection of fluid around the lung – is attributable to asbestos, and is an inflammation generated by reaction to asbestos fibers. When the pleural fluid becomes substantial the patient may have symptoms such as shortness of breath.