| Occupational asthma is a breathing disorder caused by inhaling irritating substances in a particular occupational environment. The term does not apply to irritating stimuli encountered outside of the workplace. It is characterized by wheezing, chest tightness, shortness of breath, and cough; the symptoms tend to worsen as the work week progresses, and lessen or completely resolve on weekends or during vacations. It can occur for the first time in a person who has been previously healthy, or a case of pre-existing asthma can be aggravated by workplace exposures. A wide array of substances can trigger occupational asthma, including dust, pollen, chemical fumes, gases, animal proteins, tobacco, synthetic dyes, etc. Even substances that are not normally considered harmful or dangerous can be responsible if the individual is exposed to high levels over long periods of time (e.g., flour can trigger symptoms in a professional baker).
Occupational asthma develops through one of three distinct mechanisms. The first involves direct contact with a high concentration of irritant that provokes occupational asthma without any period of latency. Irritants in this category include chemicals such as hydrochloric acid, sulfur dioxide, ammonia, etc. Asthma caused by direct contact with these irritants is often referred to as reactive airways dysfunction syndrome (RADS). Workers who already have asthma or some other respiratory disorder are particularly affected by these types of irritants. The second mechanism through which occupational asthma develops includes allergies that appear after a latent period of long-term exposure (months to years) to a work-related substance. Examples of irritants that provoke an allergic-type occupational asthma to develop after long-term exposure include food products, animal proteins, plastics, rubber, resins, enzymes, latex, etc. The third mechanism causing occupational asthma occurs when aerosolized particles of certain substances are inhaled and result in an accumulation of a naturally occurring chemical in the body. For example, insecticides used in agricultural work can cause a buildup of a chemical called acetylcholine, which causes airway muscles to constrict, resulting in asthma.
Individuals who smoke are frequently at a greater risk of developing occupational asthma, as are people with a family history of asthma or allergy. Certain professions also present higher risks. The highest incidence rates of occupational asthma are among plastics workers, printers, metal workers, bakers, millers, farmers, grain elevator workers, laboratory workers, drug manufacturers, and detergent manufacturers.Risk: Occupational asthma affects anyone of working age, from the young adult to those of retirement age. Incidence and Prevalence: Occupational asthma has become the most common work-related lung disease in developed nations. An estimated 11 million workers are exposed to at least one of the many agents known to be linked with occupational asthma. Up to 15% of disabling asthma cases have occupation-related factors ("Occupational Asthma"). |
Source: Medical Disability Advisor
| History: Common symptoms include wheezing, difficulty breathing, shortness of breath, a feeling of tightness in the chest, hives (urticaria), and coughing. Often, wheezing or coughing at night are the only symptoms. Other symptoms may include sneezing, inflammation of the nose (rhinitis) that manifests as an itchy, blocked, reddened, or runny nose, and watery, itchy, or glazed eyes. The individual may relate a pattern of exposure and symptoms that connect the condition with the workplace; however, this relationship is not always initially clear and may not be reported. Physical exam: Breathing sounds may reveal wheezing unless the symptoms resolve prior to the examination. The diagnosis of occupational asthma is largely based on history, exposure patterns, and tests. Tests: Pulmonary function tests (PFTs), which measure the efficiency of lung function (including lung volume, total lung capacity, and residual volume), are often performed. If an allergic response is suspected, a skin test may be performed; this involves placing small amounts of the suspected irritant directly onto the skin and watching for a reaction. During a bronchial provocation test, the individual inhales a small amount of the suspected irritant and the response is measured. In addition, if feasible, serial spirometry or peak flow readings during the work day, ideally at the work environment, may be helpful. A chest x-ray and blood tests may be recommended to rule out other causes of breathing difficulty. |
Source: Medical Disability Advisor
| The most important aspect of treatment is preventing additional exposure to the irritating agent. Continued exposure will lead to more severe and persistent symptoms. In some industries, where exposure cannot be eliminated (for example, flour cannot be eliminated from the environment of a professional baker), the individual's job and responsibilities will need to be changed. To control symptoms, medications that open the airways (bronchodilators) are often prescribed. Anti-inflammatory/anti-allergic medicines (corticosteroids) are usually also required to suppress the immune response. |
Source: Medical Disability Advisor
| If exposure to the irritating agent is eliminated, full recovery is likely. However, with repeated exposure, symptoms will become more severe and persistent. The outcome in these cases is less optimistic. In very rare, severe cases, death may occur. |
Source: Medical Disability Advisor
| Occupational asthma does not usually involve any complications. In very severe cases, however, respiratory distress and death could occur. |
Source: Medical Disability Advisor
| Eliminating exposure to the offending irritant is critical to the individual's recovery. If protective measures cannot be put into place, reassignment to another position within the company where exposure can be avoided may be necessary. If exposure cannot be controlled, the individual may need to change jobs entirely. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Have other conditions with similar symptoms been eliminated (foreign body aspiration, cystic fibrosis, viral respiratory infection, epiglottitis, bronchopulmonary aspergillosis, tuberculosis, hyperventilation syndrome, mitral valve prolapse, habitual cough, recurrent pulmonary emboli, congestive heart failure, chronic obstructive pulmonary disease, and hypersensitivity pneumonitis)?
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Does individual have any underlying conditions, such as other respiratory or allergic diseases, that may impact recovery?
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Has individual experienced any episodes of respiratory distress?
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If objective evidence is scant or absent, have psychological causes been considered?
Regarding treatment:
- Has individual been able to avoid contact with or exposure to the irritating substance?
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Has a job change been considered?
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Is individual being treated with medications, such as bronchodilators or corticosteroids? If so, is individual compliant with the usage instructions prescribed?
Regarding prognosis:
- Has individual been able to avoid contact with or exposure to the irritating substance?
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Has a job change been considered?
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Source: Medical Disability Advisor
| "Occupational Asthma." OSHA. 20 Nov. 2003. U.S. Department of Labor. 16 Dec. 2004 <http://www.osha.gov/SLTC/occupationalasthma/>. |
Source: Medical Disability Advisor
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