Occupational asthma is asthma that's caused by breathing in chemical fumes, gases, dust or other substances on the job. Occupational asthma can result from exposure to a substance you're sensitive to — causing an allergic or immunological response — or to an irritating toxic substance.

Like other types of asthma, occupational asthma can cause chest tightness, wheezing and shortness of breath. People with allergies or with a family history of allergies are more likely to develop occupational asthma.

Avoidance of occupational triggers is an important part of management. Otherwise, treatment for occupational asthma is similar to treatment for other types of asthma and generally includes taking medications to reduce symptoms. If you already have asthma, sometimes treatment can help it from becoming worse in the workplace.

If it's not correctly diagnosed and you are not protected or able to avoid exposure, occupational asthma can cause permanent lung damage, disability or death.

Occupational asthma symptoms are similar to those caused by other types of asthma. Signs and symptoms may include:

• Wheezing, sometimes just at night
• Coughing
• Shortness of breath
• Chest tightness

Other possible accompanying signs and symptoms may include:

• Runny nose
• Nasal congestion
• Eye irritation and tearing

Occupational asthma symptoms depend on the substance you're exposed to, how long and how often you're exposed, and other factors. Your symptoms may:

• Get worse as the workweek progresses, go away during weekends and vacations, and recur when you return to work.
• Occur both at work and away from work.
• Start as soon as you're exposed to an asthma-inducing substance at work or only after a period of regular exposure to the substance.
• Continue after exposure is stopped. The longer you're exposed to the asthma-causing substance, the more likely you'll have long-lasting or permanent asthma symptoms.

When to see a doctor

Seek immediate medical treatment if your symptoms worsen. Severe asthma attacks can be life-threatening. Signs and symptoms of an asthma attack that needs emergency treatment include:

• Rapid worsening of shortness of breath or wheezing
• No improvement even after using a quick relief inhaler
• Shortness of breath even with minimal activity

Make an appointment to see a doctor if you have breathing problems, such as coughing, wheezing or shortness of breath. Breathing problems may be a sign of asthma, especially if symptoms seem to be getting worse over time or appear to be aggravated by specific triggers or irritants.

More than 250 workplace substances have been identified as possible causes of occupational asthma. These substances include:

• Animal substances, such as proteins found in dander, hair, scales, fur, saliva and body wastes.
• Chemicals used to make paints, varnishes, adhesives, laminates and soldering resin. Other examples include chemicals used to make insulation, packaging materials, and foam mattresses and upholstery.
• Enzymes used in detergents and flour conditioners.
• Metals, particularly platinum, chromium and nickel sulfate.
• Plant substances, including proteins found in natural rubber latex, flour, cereals, cotton, flax, hemp, rye, wheat and papain — a digestive enzyme derived from papaya.
• Respiratory irritants, such as chlorine gas, sulfur dioxide and smoke.

Asthma symptoms start when your lungs become irritated (inflamed). Inflammation causes several reactions that restrict the airways, making breathing difficult. With occupational asthma, lung inflammation may be triggered by an allergic response to a substance, which usually develops over time. Alternatively, inhaling fumes from a lung irritant, such as chlorine, can trigger immediate asthma symptoms in the absence of allergy.

The intensity of your exposure increases your risk of developing occupational asthma. In addition, you will have increased risk if:

• You have existing allergies or asthma. Although this can increase your risk, many people who have allergies or asthma do jobs that expose them to lung irritants and never have symptoms.
• Allergies or asthma runs in your family. Your parents may pass down a genetic predisposition to asthma.
• You work around known asthma triggers. Some substances are known to be lung irritants and asthma triggers.
• You smoke. Smoking increases your risk of developing asthma if you are exposed to certain types of irritants.

High-risk occupations

It's possible to develop occupational asthma in almost any workplace. But your risk is higher if you work in certain occupations. Some of the riskiest jobs and the asthma-producing substances associated with them include the following:

The longer you're exposed to a substance that causes occupational asthma, the worse your symptoms may become — and the longer it will take for them to improve once you end your exposure to the irritant. In some cases, exposure to airborne asthma triggers can cause permanent lung changes, resulting in disability or death.

The best way to prevent occupational asthma is for workplaces to control the workers' level of exposure to chemicals and other substances that may be sensitizers or irritants. Such measures can include implementing better control methods to prevent exposures, using less harmful substances and providing personal protective equipment (PPE) for workers.

Although you may rely on medications to relieve symptoms and control inflammation associated with occupational asthma, you can do several things on your own to maintain overall health and lessen the possibility of attacks:

• If you smoke, quit. In addition to all its other health benefits, being smoke-free may help prevent or lessen symptoms of occupational asthma.
• Get a flu vaccination. This can help prevent illness.
• Avoid nonsteroidal anti-inflammatory drugs (NSAIDS) and other medications that may make symptoms worse.
• Lose weight. For people who are obese, losing weight can help improve symptoms and lung function.

If you are in the United States and you have a job in a high-risk profession, your company has legal responsibilities to help protect you from hazardous chemicals. Under guidelines established by the Occupational Safety and Health Administration (OSHA), your employer is required to do the following:

• Inform you if you'll be working with any hazardous chemicals.
• Train you how to safely handle these chemicals.
• Train you how to respond to an emergency, such as a chemical spill.
• Provide protective gear, such as masks and respirators.
• Offer additional training if a new chemical is introduced to your workplace.

Under OSHA guidelines, your employer is required to keep a material safety data sheet (MSDS) for each hazardous chemical used in your workplace. This is a document that must be submitted by the chemical's manufacturer to your employer. You have a legal right to see and copy such documents. If you suspect you're allergic to a certain substance, show the MSDS to your doctor.

While at work, be alert for unsafe and unhealthy working conditions and report them to your supervisor. If necessary, call OSHA at 800-321-OSHA (800-321-6742) and ask for an on-site inspection. You can do this so that your name won't be revealed to your employer.

Diagnosing occupational asthma is similar to diagnosing other types of asthma. However, your doctor will also try to identify whether a workplace substance is causing your symptoms and what it may be.

An asthma diagnosis needs to be confirmed with lung (pulmonary) function tests and an allergy skin prick test. Your doctor may order blood tests, X-rays or other tests to rule out a cause other than occupational asthma.

Testing your lung function

Your doctor may ask you to perform lung function tests. These include:

• Spirometry. This noninvasive test, which measures how well you breathe, is the preferred test for diagnosing asthma. During this 10- to 15-minute test, you take deep breaths and forcefully exhale into a hose connected to a machine called a spirometer. If certain key measurements are below normal for a person of your age and sex, your airways may be blocked by inflammation — a key sign of asthma.

  Your doctor has you inhale a bronchodilator drug used in asthma treatment, then retake the spirometry test. If your measurements improve significantly, it's likely you have asthma.

• Peak flow measurement. Your doctor may ask you to carry a small hand-held device that measures how fast you can force air out of your lungs (peak flow meter). The slower you are able to exhale, the worse your condition. You'll likely be asked to use your peak flow meter at selected intervals during working and nonworking hours. If your breathing improves significantly when you're away from work, you may have occupational asthma.

Tests for causes of occupational asthma

Your doctor may do tests to see whether you have a reaction to specific substances. These include:

• Allergy skin tests. Doctors will prick your skin with purified allergy extracts and observe your skin for signs of an allergic reaction. These tests can't be used to diagnose sensitivities to chemicals but may be useful in evaluating sensitivity to animal dander, mold, dust mites and latex.
• Challenge test. You inhale an aerosol containing a small amount of a suspected chemical to see if it triggers a reaction. Doctors test your lung function before and after the aerosol is given to see whether it affects your ability to breathe.

Avoiding the workplace substance that causes your symptoms is critical. However, once you become sensitive to a substance, tiny amounts may trigger asthma symptoms, even if you wear a mask or respirator.

The goal of treatment is to prevent symptoms and stop an asthma attack in progress. You may need medications for successful treatment. The same medication guidelines are used to treat both occupational and nonoccupational asthma.

The right medication for you depends on a number of things, including your age, symptoms, asthma triggers and what seems to work best to keep your asthma under control.

Medications include:

Long-term control medications

• Inhaled corticosteroids. Inhaled corticosteroids reduce inflammation and have a relatively low risk of side effects.
• Leukotriene modifiers. These controller medications are alternatives to corticosteroids.
• Long-acting beta agonists (LABAs). LABAs open the airways and reduce inflammation. For asthma, LABAs generally should only be taken in combination with an inhaled corticosteroid.
• Combination inhalers. These medications contain an LABA and a corticosteroid.

Quick-relief, short-term medications

• Short-acting beta agonists. These medications ease symptoms during an asthma attack.
• Oral and intravenous corticosteroids. These relieve airway inflammation for severe asthma. Long-term, they cause serious side effects.

If you find you need to use a quick-relief inhaler more often than your doctor recommends, you may need to adjust your long-term control medication.

Also, if your asthma is triggered or worsened by allergies, you may benefit from allergy treatment. Allergy treatments include oral and nasal spray antihistamines and decongestants.

While many people claim alternative remedies reduce asthma symptoms, in most cases more research is needed to see if they work and if they have possible side effects, especially in people with allergies and asthma. A number of alternative treatments have been tried for asthma, but there's no clear, proven benefit from treatments such as:

• Breathing techniques. These include structured breathing programs such as the Buteyko method, the Papworth method, lung-muscle training and yoga breathing exercises (pranayama). While these techniques may help improve quality of life, they have not proved to improve asthma symptoms.
• Acupuncture. This technique has roots in traditional Chinese medicine. It involves placing very thin needles at strategic points on your body. Acupuncture is safe and generally painless, but evidence for its use in asthma is inconclusive.

You're likely to start by seeing your primary doctor. Or you may start by seeing a doctor who specializes in asthma (allergist-immunologist or pulmonologist).

Here's some information to help you prepare for your appointment.

What you can do

• Be aware of any pre-appointment restrictions. When you make the appointment, ask if there's anything you need to do in advance. You may need to stop taking antihistamines if you're likely to have an allergy skin test.
• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Note the timing of your asthma symptoms — for example, note if your symptoms are worse at work and get better when you're away from work.
• Make a list of all possible workplace lung irritants and anything else that seems to trigger your symptoms. You may want to take a look at the material safety data sheet (MSDS) for your work area, if there is one. Usually kept in a binder near your work area, this sheet lists toxic substances and irritants used on your job site. (Keep in mind, not all occupational asthma triggers are listed in the MSDS).
• Write down key personal information, including major stresses or recent life changes and changes in your job or workplace.
• Bring a list of all medications, vitamins or supplements you take.
• Bring a family member or friend along, if possible. Someone who accompanies you may remember information you missed or forgot.
• Write down questions to ask your doctor.

For occupational asthma, some basic questions to ask your doctor include:

• Is a workplace irritant a likely cause of my breathing problems or asthma flare-ups?
• Other than the most likely cause, what are other possible causes for my symptoms or condition?
• What tests do I need? Do these tests require any special preparation?
• Is my condition likely temporary or chronic?
• How do I treat occupational asthma? Do I have to quit my job?
• What are the alternatives to the primary approach you're suggesting?
• I have other health conditions. How can I best manage these conditions together?
• Are there restrictions that I need to follow?
• Should I see a specialist?
• Is there a generic alternative to the medicine you're prescribing?
• Are there brochures or other printed material I can take with me? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

• When did you first notice your symptoms?
• How severe are your symptoms?
• Do you have breathing problems when you're away from work or only when you're on the job?
• Have your symptoms been continuous, or do they come and go?
• Have you been diagnosed with allergies or asthma?
• Are you exposed to fumes, gases, smoke, irritants, chemicals, or plant or animal substances at work? If so, how often and for how long?
• Do you work in unusual environmental conditions, such as extreme heat, cold or dryness?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?
• Do allergies and asthma run in your family?