Asbestosis

Asbestosis is a breathing disorder caused by inhaling high levels of 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 it 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 and only at a remote risk of malignant mesothelioma, a rare cancer of the membranes lining the chest and abdominal cavities.

Signs and symptoms

The effects of long-term exposure to asbestos typically don’t show up for 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).

Some of the signs and symptoms of asbestosis include:

• Shortness of breath, initially only with exertion, but eventually even while resting
• Decreased tolerance for physical activity
• Coughing
• Chest pain
• Finger clubbing in some cases

Although most of these signs and symptoms are similar to those of a condition 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 — air’s main passageway 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 tiny 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 filtered out by being trapped in your nose hairs or being 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 that 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 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:

• Pulmonary function tests. These tests determine how well your lungs are functioning and may help in the diagnosis. Pulmonary function tests measure how much air your lungs can hold and the airflow in and out of your lungs. For example, you may be asked to blow as hard as you can into an air-measurement device called a spirometer. Some pulmonary function tests measure the amount of gas exchanged across the membrane between your alveoli and capillary blood vessels.
• Chest X-ray. A chest X-ray can often detect abnormalities in your lungs. On an X-ray, areas of scar tissue that appear as small, scattered, opaque areas on the lining of your lungs are called pleural plaques. Although they indicate previous exposure to asbestos, they are not a predictor of asbestosis or malignant mesothelioma. Asbestosis appears as excessive whiteness in your lung tissue. If the asbestosis is advanced, your entire lung may be affected, giving it a honeycomb appearance.
• Computerized tomography (CT) scan. In some cases, your doctor may request a computerized tomography (CT) scan of your lungs. These scans generally provide greater detail than a usual chest X-ray. This may help detect asbestosis in its early stages, even before it shows up on the chest X-ray.

Chest X-rays: Helping detect heart and lung conditions

CT scan

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:

• High blood pressure in your lungs. Asbestosis-related scar tissue may eventually compress or obliterate your lungs’ small blood vessels, causing high blood pressure in your lungs’ arteries (pulmonary hypertension).
• Heart problems. Pulmonary hypertension can lead to enlargement and failure of your heart’s right ventricle (cor pulmonale). Your heart consists of four chambers — two upper chambers called atria and two lower chambers called ventricles. Your right ventricle assists in pumping oxygen-poor blood from your organs and tissues to your lungs, where your blood receives a new boost of oxygen. As your pulmonary arteries narrow, your heart’s right ventricle must work harder to pump blood through the lungs. Initially, the heart tries to compensate by thickening its walls and dilating the right ventricle to increase the amount of blood it can hold. But this measure only works temporarily, and eventually — after a period of a few years — the right ventricle weakens and fails from the extra strain.
• Lung cancer. If you smoke and have asbestosis, your chances of developing lung cancer increase greatly, especially if you smoke more than a pack a day. Tobacco smoke and asbestos both contribute to each other’s cancer-causing (carcinogenic) effects, so that the combination of both risk factors together is more dangerous than the effects of either risk factor alone.
• Other lung damage. Exposure to asbestos can lead to other health complications including changes in the thin membranes covering your lungs and lining your chest cavity (pleural membranes). Pleural changes may be the first signs of asbestos exposure and may include pleural thickening, the formation of calcium deposits in the pleura (plaques), and an abnormal accumulation of fluid between the membranes (pleural effusion). Pleural effusion itself is benign and doesn’t increase your risk of asbestosis or malignant mesothelioma.
• Other cancer. Prolonged exposure — 20 years or more — to asbestos can also lead to malignant mesothelioma. Diagnosis and treatment of this cancer is often difficult. Malignant mesothelioma may occur even many years after exposure has stopped.

Pulmonary hypertension

Lung cancer

Treatment

There’s no treatment to reverse the effects of asbestos on the alveoli. Treatment is aimed at 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 treatment for asbestosis:

• Smoking cessation. If you smoke, it’s important to stop, particularly because of the extremely heightened risk of lung cancer. In addition, smoking may cause emphysema, which further reduces your lung reserves.
• Vaccinations. Because of your impaired lung condition, treat a cold or a bout of the flu promptly to avoid complications. Your doctor may advise you to receive flu and pneumonia vaccines.
• Medications. The complication of pulmonary hypertension is often treated with medications to expand or relax blood vessels, and blood-thinning medications to prevent blood clots from forming and obstructing narrowed vessels.

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.

Common cold

Influenza (Flu)

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.