Occupational Asthma

Facts on Occupational Asthma

Asthma is a chronic (long-term, ongoing) inflammation of the breathing passages (bronchi) of the lungs. The inflammation irritates the airway, causing breathing problems.

  • Most people with asthma have sudden attacks or periods of bothersome or severe symptoms separated by periods of mild symptoms or no symptoms at all.
  • Asthma is an inflammatory reaction that is triggered by external factors or specific situations.
  • When a person with asthma is exposed to one of his or her triggers, the inflammation worsens and symptoms ensue.

Occupational asthma is a breathing (respiratory) disease caused by exposure to a trigger in the workplace. A trigger is an external factor or condition in the body that causes the asthma to occur or worsen. The list of known triggers is long and varied.

  • The trigger generally is something inhaled.
  • Occupational asthma can occur in almost any line of work or any work environment, including offices, stores, hospitals, and medical facilities.
  • Triggers of asthma include contaminants in the air, such as smoke, chemicals, vapors (gases), fumes, dust, or other particles; respiratory infections, such as colds and flu (viruses); allergens in the air, such as molds, animal dander, and pollen; extremes of temperature or humidity; and emotional excitement or stress.

Four types of occupational asthma attacks occur.

  • Aggravation of preexisting asthma: This is by far the most common type. Over time, with regular exposure, you develop hypersensitivity to the trigger. With this underlying asthma, continued exposure to the trigger causes attacks.
  • Immunologic asthma is characterized by a delay in the onset of symptoms.
  • Nonimmunologic asthma seems to occur after single or multiple exposures to irritant material.
  • Mixed forms can include components of the three other mechanisms described above.

Once the attack is triggered, the airways begin to swell and tighten (bronchospasm) and secrete large amounts of mucus.

  • The swelling and extra mucus partially block, or obstruct, the airways. This makes it more difficult to push air out of your lungs (exhale).
  • If this occurs for a period of time, the inflammation can result in abnormal airflow obstruction even when not having an attack. When lung function no longer returns to normal after years of chronic inflammation, asthma evolves into a new class of lung disease referred to as chronic obstructive pulmonary disease (COPD).

Asthma cannot be cured, but it can be controlled by medication.

  • You have a better chance of controlling your asthma if it is diagnosed early and treatment begun right away.
  • With proper treatment, you can have fewer and less severe attacks.
  • Without treatment, you will have more frequent and more severe attacks. You can even die from a severe asthma attack.

Early recognition and avoidance of the asthma trigger is particularly important in occupational asthma.

  • Because people spend so much time at work, they tend to have extensive exposure to their trigger by the time the cause of the symptoms is recognized as asthma.
  • The more time you spend exposed to your trigger, the more likely you are to have permanent lung inflammation and airway hypersensitivity.

Occupational asthma is the most common work-related lung disease in developed countries. In some people with asthma in the United States, the condition is at least partly related to their work.

Asthma:An Inflammatory Disorder of the Airways

What causes occupational asthma?

Asthma has two components: the underlying chronic inflammation and the periodic attacks. We do not know for certain what causes the underlying inflammation. What we do know is that the tendency to have asthma runs in families and that some people are born with the tendency.

We do know what causes asthma attacks: exposure to a trigger. The attack is similar in many ways to an allergic reaction.

  • An allergic reaction is a response by the body's immune system to an "invader." That invader can be a substance or anything that the body senses as "different."
  • When the cells of the immune system sense an invader, they set off a series of reactions that help fight off the invader.
  • It is this series of reactions that causes the production of mucus and bronchospasms. These responses cause the symptoms of an asthma attack.

In occupational asthma, the trigger is a substance or condition in the workplace that causes asthma symptoms. Most of these substances and conditions are very common and are not normally considered hazardous. Although these substances and conditions can be encountered in almost any workplace, occupational asthma is most common in workers in the following industries and jobs:

  • Plastics industry
  • Rubber industry
  • Chemical industry
  • Textile industry
  • Electronics industry
  • Painting
  • Printing
  • Dyeing
  • Metalworking
  • Welding
  • Oil refining
  • Cleaning
  • Baking and food processing
  • Farming
  • Gardening, landscaping, and horticulture
  • Working with animals
  • Laboratory work

Triggers that are often associated with a delay in the onset of symptoms (latency period) come in two groups (characterized by the size of the molecules involved). These are either high molecular weight or low molecular weight agents.

The high molecular weight agents tend to be proteins, and polysaccharides. Examples of these agents include a variety of enzymes (used in the baking and food industry), cereals (also seen in the baking industries), animal waste and shellfish (found in laboratory technicians, farmers, food processors), and latex (found in health-care workers).

Low molecular agents often have a shorter onset of symptoms and usually do not include nasal and eye irritation. Some examples of these agents include anhydrides (often used in plastics, dyes, and epoxy), metals (used in refineries, electroplating, welding), diisocyanates (found in plastics, spray paints, foundries), specific wood dusts like red cedar (found in wood carvers, furniture makers, sawmill workers), and cleaning agents (found in maintenance workers health-care professionals).

Not everyone exposed to these conditions will develop asthma. Some people are more susceptible to asthma than others. Also, exposure to some of these substances can produce chronic lung diseases other than asthma. Risk factors for occupational asthma include the following:

If asthma is not treated, the airways gradually develop a pattern of overreacting, hence, the alternative term for asthma, reactive airways disease. Common, everyday conditions, such as cigarette smoke or cold air, may cause asthma symptoms. In fact, it is part of the normal human condition for a small degree of bronchospasm to occur when the airways are exposed to cold or dry air. Normally, the body's upper airway warms and moistens the air to prevent this from occurring.

Asthma FAQs

Asthma is a disease that affects the breathing passages, or airways, of the lungs. Asthma is a chronic (ongoing, long-term) inflammatory disease that causes difficulty breathing.

When an exacerbation or "attack" of asthma takes place, the inflammation in the airways causes the lining of the breathing passages to swell. This swelling narrows the diameter of the airway, eventually to a point where it is hard to exchange enough air to breathe comfortably. This is when coughing, wheezing, and the sensation of distress start.

What are the symptoms of occupational asthma?

In most people with occupational asthma, the symptoms appear a short time after beginning work and subside after leaving work.

  • Many have no symptoms or milder symptoms on days they do not work. The symptoms return when they return to work.
  • In some, the symptoms worsen gradually over the work week, go away over the weekend, and return when the new work week starts.
  • In others, the symptoms are slow to develop and may not be noticed until after leaving work for the day. This pattern makes it difficult to recognize a workplace trigger.
  • In the later stages of the disease, after long-term regular exposure, symptoms may not go away after you leave the workplace.

These are the most common symptoms of occupational asthma. Most people do not have all these symptoms.

Allergy symptoms that occur at work but get better away from work also may be a sign of irritants in the air that could provoke asthma symptoms. The following symptoms could occur:

  • Eyes: itchy, burning, or watery
  • Nose: itchy or stuffy, sneezing
  • Skin: itchy, red, or irritated

When to Seek Medical Care for Occupational Asthma

If you have asthma symptoms at work that get better away from work, make an appointment with your health-care provider promptly.

If you have occupational asthma, you should have an action plan worked out in advance with your health-care provider. This plan should include instructions on what to do when an asthma attack occurs, when to call the health-care provider, and when to go to a hospital emergency department.

Although asthma is a reversible disease, and treatments are available, people can die from a severe asthma attack.

  • If you are having an asthma attack and have severe shortness of breath or are unable to reach your health-care provider in a short period of time, you must go to the nearest hospital emergency department.
  • Do not drive yourself to the hospital. Have a friend or family member drive. If you are alone, call 911 immediately for emergency medical transport.
Asthma:An Inflammatory Disorder of the Airways

Occupational Asthma Diagnosis

If you have had asthma symptoms and are seeking medical care afterward, your health-care provider will ask questions and perform tests to pinpoint the cause of the symptoms.

Proper diagnosis is essential to ensure that the most appropriate treatment is given. Your health-care provider should confirm and document that you have asthma before beginning treatment.

You should undergo breathing tests to determine the condition of your airways.

  • Spirometry: The spirometer is a device that measures how much air you can exhale and how forcefully you can breathe out. Spirometry is a good way to see how much your breathing is impaired during an attack. This test must be done in the medical office; you may exercise on a treadmill or stationary bicycle or perform the tests before and after using an inhaled medication.
  • Peak flow meter: This is another way of measuring how forcefully you can breathe out during an attack. This device is small and portable and can be used "in the field." This device can be very helpful. It is inexpensive and monitoring can be done at various times of the day to help detect any patterns associated with the reactive airways process.

These tests may be done at the workplace to determine how your airways react to the work environment. The tests are performed before you go to the workplace and then after you have been in the workplace for some time, and the results are compared.

  • Many employers have a health worker at the workplace who can carry out these tests.
  • The company's representative often will work with you and your health-care provider to determine what is causing your symptoms.
  • The company should cooperate in evaluating workplace exposures as possible triggers of asthma.

There is no blood test than can pinpoint the cause of asthma.

  • Your blood may be checked for signs of an infection that might be contributing to the symptoms.
  • In severe attacks, it may be necessary to sample blood from an artery to determine exactly how much oxygen and carbon dioxide are present in your body.

A chest X-ray may also be taken. This is mostly to rule out other conditions that can cause similar symptoms.

What is the treatment for occupational asthma?

Treatment in occupational asthma depends on how severe the asthma is.

  • Prevention is always the first choice of treatment. If your asthma is not very severe, prevention may be enough to avoid symptoms. For some people, just avoiding exposure to the trigger is possible and is enough to prevent symptoms; for others, a combination of avoiding the trigger and medication can prevent symptoms.
  • People with severe occupational asthma may need to consider changing to a different job or a different line of work.

The goals of treatment are as follows:

  • To prevent asthma attacks
  • To carry on with normal activities
  • To maintain normal or near-normal lung function
  • To have as few medication side effects as possible

Are there home remedies for occupational asthma?

Work with your health-care provider to develop an action plan. Follow your treatment plan closely to avoid asthma attacks. If you do have an asthma attack, the action plan will help you control the attack and make the decision about when to seek medical care.

Since occupational asthma is a chronic disease, you will probably require treatment for a very long time, maybe even for the rest of your life. The best way to improve your condition and live your life on your terms is to learn all you can about your asthma and what you can do to make it better.

  • Become a partner with your health-care provider and his or her support staff. Use the resources they can offer - information, education, and expertise - to help yourself.
  • Follow the treatment recommendations of your health-care provider. Understand your treatment. If you are taking medication, know what each drug does and how it is used.
  • See your health-care provider as scheduled.
  • Promptly report any changes or worsening of your symptoms.
  • Report any side effects you are having with your medications.

Precautions that may help reduce your chance of having an asthma attack include the following:

  • Avoid the trigger. In many cases, this doesn't mean you have to quit your job or change your occupation, although you may want to consider that. Most employers will work with you to reduce or remove your exposure to the trigger in the workplace.
  • Take your medications as directed.
  • If you smoke, quit.

If you should have an asthma attack, move to the next step of your action plan. Keep the following tips in mind:

  • Take only the medications your health care provider has prescribed for your asthma. Take them as directed.
  • If the medication is not working, do not take more than you have been directed to take. Overusing asthma medications can be dangerous.
  • Do not take cough medicine. These medicines do not help asthma and may cause unwanted side effects.
  • Do not use nonprescription inhalers. These contain a very short-acting inhaler that may not last long enough to relieve an asthma attack and may cause unwanted side effects.
  • These contain a very short-acting inhaler that may not last long enough to relieve an asthma attack and may cause unwanted side effects.
  • Aspirin (Bayer) and nonsteroidal anti-inflammatory drugs, such as ibuprofen (Advil), can cause asthma to worsen in certain individuals. These medications should not be taken without the advice of your health-care provider.
  • Do not take any nonprescription preparations, herbs, or supplements, even if they are completely "natural," without talking to your health-care provider first. Some of these may have unwanted side effects or interfere with your medications.
  • Be prepared to go on to the next step of your action plan if necessary.

If you think your medication is not working, let your health-care provider know right away.

Asthma:An Inflammatory Disorder of the Airways

Medical Treatment for Occupational Asthma

The most important part of treating occupational asthma is avoiding the trigger.

  • Most people assume that means quitting their job and changing their occupation, but this is not always the case.
  • Many employers will work with you to reduce or stop your exposure. This may mean changing the way things are done in the workplace overall or it may mean providing extra protection for you. It may mean moving you to a different location in the workplace.
  • Because acceptable solutions often can be found, many asthma specialists recommend not quitting your job until all possibilities have been exhausted. If your asthma is very severe or cannot be controlled in the workplace, however, you may have to leave your job right away.

Once the diagnosis of asthma has been confirmed, you may be started on a regimen of medications. Asthma medications are of the following two types:

  • Controller medications: These are for long-term control of persistent asthma. They help to keep airways open and reduce the inflammation in the lungs that underlies asthma attacks. You take these every day whether you are having symptoms or not.
  • Rescue medications: These are for short-term control of asthma attacks. You take these only when you are having symptoms or are more likely to have an attack; for example, when you have an infection in your respiratory tract.

Your treatment plan will also include the following:

  • Awareness of your trigger and avoiding the trigger as much as possible
  • Recommendations for coping with asthma in your daily life
  • Regular follow-up visits to your health-care provider to monitor your condition, whether you are on medication or not

Together, you and your health-care practitioner will develop an action plan for you in case of asthma attack. The action plan will include the following:

  • How to use rescue medication
  • What to do if the rescue medication does not work right away
  • When to call the health-care provider
  • When to go directly to a hospital emergency department

Your health-care practitioner may want you to use a peak flow meter regularly, at least at first, to monitor how being at work affects your airway. The peak flow meter is a simple, inexpensive device that measures how forcefully you are able to exhale.

  • This is a good way to help you and your health-care provider assess the severity of your asthma.
  • Ask your health-care practitioner or an assistant to show you how to use the peak flow meter. He or she should watch you use it until you can do it correctly.
  • Keep a record of the results. Over time, your health-care practitioner may be able to use this record to improve your medications, reducing dose or side effects.
  • Peak flow measures fall just before an asthma attack. If you use your peak flow meter regularly, you may be able to predict when you are going to have an attack.
  • It can also be used to check your response to rescue medications.

Occupational Asthma Medications

Controller medications are for long-term control of persistent asthma. They help to keep airways open and reduce the inflammation in the lungs that underlies asthma attacks. Controller medications include long-acting beta-agonists and anti-inflammatory medicines.

Long-acting beta-antagonists: This class of drugs is chemically related to adrenaline, a hormone produced by the adrenal glands. Inhaled long-acting beta-agonists work to keep breathing passages open for 12 hours or longer. They relax the muscles of the breathing passages, dilating the passages and decreasing the resistance to exhaled airflow, making it easier to breathe. They also may help to reduce inflammation, but they have no effect on the underlying cause of the asthma attack. Side effects include rapid heartbeat and shakiness. Salmeterol (Serevent) and formoterol (Foradil) are long-acting beta-agonists.

Anti-inflammatory medicines minimize the inflammation that underlies an acute asthma attack. Generally these medications do not help during an attack, but you should continue to take them during an attack.

  • Inhaled corticosteroids are the main class of medications in this group. The inhaled steroids act locally by concentrating their effects directly within the breathing passages, with very few side effects outside of the lungs. Beclomethasone (Vancenase, Beclovent), fluticasone (Flovent), budesonide (Pulmicort), and triamcinolone (Azmacort) are examples of inhaled corticosteroids.
  • Other anti-inflammatory drugs used to treat asthma include oral steroids, leukotriene inhibitors, methylxanthines, and cromolyn sodium. For more information about these medications, see Asthma and Understanding Asthma Medications.

Rescue medications are bronchodilators. They quickly open the airways closed off by swelling, bronchospasm, and mucus. These are taken after an asthma attack has already begun. These do not take the place of anti-inflammatory drugs. Do not stop taking your anti-inflammatory drug(s) during an asthma attack.

  • Short-acting beta2-agonists are the most commonly used rescue medications. This class of drugs is chemically related to adrenaline, a hormone produced by the adrenal glands. Inhaled beta2-agonists work rapidly (within minutes) to open the breathing passages. They relax the muscles of the breathing passages, dilating the passages and decreasing the resistance to exhaled airflow, making it easier to breathe. They do not reduce inflammation and have no effect on the underlying cause of the asthma attack. Side effects include rapid heart beat and shakiness. Albuterol (Proventil HFA, Ventolin HFA, ProAir) is the most frequently used beta2-agonist medication.
  • Anticholinergics are another class of drugs useful as rescue medications during asthma attacks. Inhaled anticholinergic drugs open the breathing passages, similar to the action of the beta2-agonists. Inhaled anticholinergics take slightly longer than beta2-agonists to achieve their effect, but they last longer than the beta2-agonists. An anticholinergic drug is often used together with a beta2-agonist drug to produce a greater effect than either drug can achieve by itself. Ipratropium bromide (Atrovent) is the inhaled anticholinergic drug currently used as a rescue asthma medication.
  • Tiotropium (Spiriva), a long-acting anticholinergic, is now also being used as a maintenance medicine in more severe cases of asthma.
  • Combination therapy which includes a long-acting beta2 agonist and inhaled corticosteroid available in a single inhaler is now commonly used in asthma (for example, Advair, Symbicort, Dulera).

Occupational Asthma Follow-up

Asthma is a long-term disease, but it can be managed. Your active involvement in treating this disease is vitally important.

  • Take your prescribed medication(s) as directed.
  • See your health-care practitioner regularly according to the recommended schedule.
  • By following these steps, you can help minimize the frequency and severity of your asthma attacks.

At your follow-up visits, your health-care practitioner will review how you have been doing.

  • He or she will ask you about frequency and severity of attacks, use of rescue medications, and peak flow measurements.
  • Lung functions tests will be done to see how your lungs are responding to your treatment.
  • This is a good time to discuss medication side effects or any problems you are having with your treatment.

Occupational Asthma Prevention

Treatment in occupational asthma is focused on preventing or minimizing asthma attacks. The main strategy for doing this is reducing or stopping exposure to the trigger.

  • Work with your employer to "clean up" the workplace.
  • You or your health-care provider should be able to arrange for measurement of air quality in the workplace.
  • Your employer should provide protective gear, such as masks or respirators, to avoid exposure to the trigger.
  • Careless use or spills of respiratory irritants, inappropriate ventilation, and improper protective gear contribute to the occurrence of asthma in the workplace. These problems can be remedied.
  • If these measures don't reduce your symptoms, talk to your employer about retraining for a different position that would not involve exposure to your trigger.

Occupational Asthma Prognosis

Most people with occupational asthma are able to control their condition if they work together with a health-care provider and follow their treatment regimen carefully.

People who do not seek medical care or do not follow an appropriate treatment plan are likely to experience worsening of their asthma and deterioration in their ability to function normally.

Reviewed on 11/20/2017

Medically reviewed by James E. Gerace, MD; American Board of Internal Medicine with subspecialty in Pulmonary Disease


"Occupational asthma: Clinical features and diagnosis"

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