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Introduction Asbestosis is a breathing disorder caused by inhaling asbestos fibers. Prolonged accumulation of these fibers in your lungs can lead to scarring of lung tissue and diminished breathing capacity. Signs and symptoms of asbestosis usually don't appear until years after exposure. But once apparent, the condition often worsens and can lead to disability and even death if exposure to asbestos continues. Asbestos is a natural mineral product that's resistant to heat and corrosion. It was used extensively in the past in the building and manufacturing industries. Some of its more common uses were in pipe and duct insulation, fire-retardant materials, brake and clutch linings, cement, and some vinyl floor tiles. People most likely to develop asbestosis are those who've been exposed to asbestos for a long time. Most people with asbestosis acquired it on the job before the federal government began regulating the use of asbestos and asbestos products in the mid-1970s. Today, its handling is strictly regulated. Still, experts estimate that since the 1940s up to 10 million people may have been exposed to asbestos. The good news is that most people with a history of prolonged exposure don't develop asbestosis, and the risk of asbestosis diminishes every day away from exposure. These days, most instances of asbestos exposure occur during removal of old asbestos products or demolition of old buildings. If you live, work or study in a building where existing asbestos has been contained and sealed, you're not at risk of asbestosis. Signs and symptoms The effects of long-term exposure to asbestos typically don't show up for at least 20 to 30 years after initial exposure. Signs and symptoms develop when damage and scarring caused by the asbestos fibers lead to stiffness in your lung tissue so that your lungs can't contract and expand normally (a form of pulmonary fibrosis). Once exposure to asbestos is stopped, however, the fibrosis does not progress. Some asbestosis symptoms include:
Although most of these signs and symptoms are similar to those of other breathing disorders, such as asthma, the way in which they develop is different. In asbestosis the effects of the disease are insidious, occurring over months and years.
Causes When you inhale, air travels through your nose or mouth, down your throat, through your larynx to your trachea — the main passageway for air to your lungs. Your trachea splits into two branches called bronchi, one carrying air to the left lung, one to the right. Within each lung, the bronchi branch off into smaller and smaller airways. Some of the smallest of these airways (bronchioles) lead into tiny ducts (alveolar ducts) that end in microscopic air sacs (alveoli). Alveoli have very thin, elastic walls that allow an exchange of gases vital to your health — oxygen flows from the alveoli into your bloodstream to nourish your body, and carbon dioxide flows from your bloodstream into the alveoli and on into your bronchi, to be expelled. Normally, microorganisms, dust and other foreign particles in the air you breathe are removed by microscopic hairs on the surface of your airways that beat hundreds of times a minute (cilia). The cilia sweep the particles into your upper airway, where the particles are swallowed into your digestive system, trapped in your nose hairs or expelled when you cough. Even when unwanted particles do get into your lungs, immune cells destroy most of them. Alveoli, for example, house their own special cleanup crew — immune cells called macrophages, which are attracted to and ingest foreign substances, such as smoke particles, dust and chemicals. Fibers resist breakdown Unfortunately, asbestos fibers are difficult to destroy, even for macrophages. When a macrophage attempts to ingest an asbestos fiber, it often fails because the fiber is too long and partially resistant to breakdown. In the process, however, the macrophage leaks out substances that were supposed to destroy the foreign body, but these substances can also harm the alveoli. This causes the alveoli to become inflamed and eventually scar, a process referred to as fibrosis. If many fibers are inhaled over a long period of time, the cumulative scarring of alveoli reduces their ability to exchange oxygen and carbon dioxide. The result is that your lung capacity diminishes, oxygen exchange is diminished, and you feel increasingly short of breath. Also, because the lungs are stiff, like a dried sponge, it takes a great deal of muscular effort to breathe.
Risk factors Because asbestos occurs naturally in the environment, everyone breathes in a certain amount of asbestos fibers. Usually, these are expelled before they reach the deeper areas of your lungs, but even if they do, a few fibers won't create signs and symptoms of asbestosis. People most at risk of developing asbestosis are those who've had at least 10 years of moderate to severe exposure to asbestos, such as workers who were involved in the mining, milling, manufacturing or installation of asbestos products. Brief exposure to asbestos a few times in your life won't cause harm. However, it's always best to avoid direct exposure. If you're about to remodel an older house, for example, you may wish to hire a professional to determine if asbestos is present. He or she can safely sample a suspected asbestos product and help you decide on the best way to proceed. Even if no asbestos can be detected, it's best to wear appropriate face masks and other protective gear when working with do-it-yourself projects, to keep you from inhaling dust, chemicals and other foreign particles. Removal of asbestos products is generally considered a major project. If you decide to have it done, seek the help of a professional. When to seek medical advice If you have a history of exposure to asbestos and you're experiencing increasing shortness of breath, talk to your doctor about the possibility of asbestosis. If it is asbestosis, your doctor may be able to prescribe treatment to relieve your symptoms. However, it's unlikely that the disease will progress after removal from exposure. Screening and diagnosis To help your doctor make an accurate diagnosis, provide him or her with a detailed history of your work activities and any other sources of possible exposure to toxic dusts. Tell your doctor about the availability of dust masks and other respiratory-protection devices in your workplace. Your doctor may also ask if you know of any fellow employees who have been diagnosed with a condition caused by exposure to asbestos. Your doctor may detect a dry, crackling sound when listening to your lungs with a stethoscope. You may also undergo these diagnostic tests:
Complications The severity of asbestosis is generally related to the amount and duration of exposure to asbestos. Effects of the disease may be so mild as to cause almost no symptoms. Or the condition may create such a reduced flow of oxygen as to be disabling or even fatal. Asbestosis may lead to the following conditions:
Treatment There's no treatment to reverse the effects of asbestos on the alveoli. Treatment focuses on preventing progression of the disease and relieving symptoms. The most important factor in keeping the condition from worsening is to eliminate exposure to asbestos. For most people, scarring of lung tissue doesn't begin or progress once exposure has ended. The following may be components of asbestosis treatment:
To ease difficulty breathing, your doctor may prescribe supplemental oxygen or drain fluid from around your lungs, if necessary. Occasionally, severe cases of asbestosis may be treated with lung transplantation. Prevention Reducing the level of exposure to asbestos is the best prevention against asbestosis. In the United States, by law, a worker's exposure to asbestos may not exceed 0.1 fiber per cubic centimeter of air. Federal law requires employers in industries that work with asbestos products, such as construction and shipyard industries, to monitor exposure levels, create regulated areas for asbestos work, and provide their employees with appropriate training, protective gear such as face masks, and decontamination hygiene areas. Many homes built before the 1970s contain asbestos products, such as building insulation, insulation for hot-water and steam pipes, soundproofing and decorative material sprayed on walls and ceilings, older stove-top and ironing board pads, as well as some types of textured paint, patch compounds, roofing and siding shingles, and vinyl floor tiles. Generally, there's no cause for concern being around these products as long as they're in good condition and you don't disturb them or cause them to disintegrate. It's when they are damaged that there's a danger of asbestos fibers being released into the air. If you need repair or removal of an asbestos product, it's best to have it done by a professional.
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