Overview
Occupational Asthma is a condition in which the person develops Asthma due to irritants in the workplace. There are multiple industries or professions where people are exposed to irritants, thereby triggering Occupational Asthma over time. The condition is life-threatening eventually, as it compromises oxygen-supply progressively, leading to many complications. In this article we will learn the causes and treatment-options for this condition.
Introduction
Asthma is a condition marked by chronic (long-term) inflammation of the airways in the lungs. It causes the airways to constrict, thereby making breathing difficult. This in turn reduces supply of fresh oxygen to the body’s cells. In earlier articles, we have covered asthma and its causes in depth.
One such cause or risk factor for asthma is Occupational Asthma (OA). Inhaling fumes and gases of inorganic chemicals, dust, and organic material such as agricultural produce, at the workplace, can cause asthma over time. This is different from seasonal asthma which is caused by inhaling pollen or mold-spores. OA is one of the most common types of adult-onset asthma.
So how does one know that he/she has developed asthma due to the workplace and not other reasons? The clues are quite obvious.
- Such people have very mild symptoms on weekends, or no symptoms at all while on a long break. Symptoms return when the person returns to work.
- Symptoms worsen as the week progresses, reduces on the weekend and returns at start of the week.
- Symptoms are mild in the morning, increase through the day and are worse by end of the work-day
- In later stages of the disease, symptoms last even on weekends, during vacations, and is severe all through the day.
Causes
There are over 400 substances at different workplaces, across industries, which have been identified as triggers or risk factors for OA. These can be classified as:
- Animal related: proteins found in saliva, dander, fur, scales, hair, urine and feces of animals and birds
- Industrial Chemicals: Such as those used to make soldering-resin, paints, adhesives, varnishes, laminates, insulation, upholstery, packaging-material and foam mattresses
- Enzymes: Synthetic enzymes used in flour-conditioners and detergents
- Metals and alloys: Nickel-sulfate and compounds of chromium and platinum
- Plant produce: Proteins found in latex or natural rubber (used in gloves), cereals, flour, wheat, rye, flax, cotton, hemp and a digestive enzyme derived from papaya called papain.
- Respiratory irritants: smoke, smog, vehicle-exhaust, chlorine gas, nitric-oxide and sulfur-dioxide.
A comprehensive list of professions where people are at risk of OA includes – adhesive handlers, animal handlers, veterinary doctors, handlers of plastics and epoxy resin, bakers, millers, textile workers, farmers, shellac handlers, carpet-makers, chemical manufacturers, loom workers, metalworkers, food-production workers, welders, forest workers or lumberjacks, carpenters, plastics and foam industry workers, hairdressers, insulation installers, healthcare workers, spray painters, pharmaceutical workers, seafood processors and bakers.
Risk-factors for OA
As is obvious, the more the exposure to irritants at the workplace, higher the risk of contracting OA. Other risk factors include:
- Existing allergies or asthma: Asthmatics who work such jobs listed above are at risk of their symptoms worsening. However, this does not happen to everybody and there are asthmatics who work such jobs and are not affected.
- Allergies or asthma runs in the family: If close blood-relatives have ordinary asthma, OA or allergies, then one may be genetically at higher risk than others.
- Smoking: Smoking is known to aggravate asthma symptoms so smokers who work such jobs are at higher risk of OA than non-smokers.
- Obesity: For no clear reason, overweight people who work such jobs are at higher risk than fellow-workers who are of normal weight.
Types of OA
Workplace irritants can cause asthma in the following ways:
- An allergic reaction: This is similar to how people with allergies develop allergic asthma
- An irritant reaction: This is similar to how an asthmatic may react negatively to cigarette smoke
- Substance build-up: Naturally-occurring chemicals such as histamines can build-up in the lungs over time and trigger reactions and asthma attacks.
Accordingly, there are different types of OA:
- Sensitizer-induced OA: This makes up over 90 percent of all OA cases. In this, repeated exposure to workplace-irritants over several months or years triggers asthma symptoms. Here, the irritant is a specific substance at the workplace and not several of them.
- Irritant-induced asthma: Here, the person is exposed directly to the irritant, triggering asthmatic symptoms. These can develop in three ways:
- within a day of exposure to a high level of a particular irritant
- after several exposures to mid-level or high-levels of that irritant
- after chronic or long-term exposure to even low or medium levels of that irritant
- Byssinosis: Also called Brown lung. Textile workers and farmers who work with unprocessed cotton, flax or hemp end-up inhaling fine particles of the same. The condition develops over time.
Symptoms
Common symptoms that are managed through medication:
- Wheezing, which in some people happens only at night
- Coughing during exercise or laughing, and at night
- Shortness of breath (dyspnea)
- Tightness in the chest
- Congestion in the nose, runny nose
- Irritation in the eyes, watering eyes
- Fatigue
Less common symptoms of Asthma that require emergency medical attention:
- rapid breathing
- severe wheezing or coughing that doesn’t stop
- inability to fully breathe in or out
- lack of relief from the rescue inhaler
- confusion or agitation
- inability to speak clearly
- Feelings of anxiousness or panic
- Bluish lips or fingernails, gray or white lips and gums
- Pressure or pain in the chest that is unbearable
Diagnosis
- Spirometry: This test measures how good is the breathing and whether the airways are blocked due to inflammation. In this, the person takes deep breaths and exhales forcefully into a pipe connected to a ‘spirometer’. The measurements are taken. Next, the person must inhale a bronchodilator drug used for treating asthma and repeat the spirometry test. If the measurements have improved significantly now, the person is likely to have asthma.
- Peak flow measurement: At selected intervals of time both during working and non-working hours, the person must exhale into a hand-held device called the peak flow meter. The faster the exhalation, less the likelihood of asthma, while slower exhalation indicates higher risk. If the exhalation is better when the person is away from work, it is indicative of OA.
- Allergy skin test: This is used to check for sensitivity to certain chemicals like latex, dust mites, animal dander and mold. The skin will be pricked with extract of these irritants and the person watched for signs of an allergic or asthmatic reaction.
- Challenge test: The Lung function as described in 1 and 2 methods above is done. Then the person must inhale an aerosol containing tiny amounts of a suspected irritant. The lung function test is done again. A significant difference indicates OA.
- Chest X-ray: OA is just one of the types of occupational lung diseases. A chest X-ray is done if other job-related breathing problems along with OA are suspected.
Treatment
The long-term treatment for OA is to change the job, and also quit smoking. If changing the job is not an option, or till that happens, medication is the only form of treatment. There are 2 kinds of drugs that will be given:
Quick-relief, short-term medications
- Short-acting beta agonists: These are given to control or reduce the symptoms during an asthma attack.
- Oral and IV corticosteroids: These relieve inflammation and congestion in the airways. These are only given to people with severe OA and that too for the short-term, as they can cause serious side effects.
Long-term control medications
- Inhaled corticosteroids: These reduce inflammation and congestion in the airways, and come with reduced risk of side effects.
- Leukotriene modifiers: An alternative to corticosteroids, or sometimes combined with them
- Long-acting beta agonists (LABAs): These open up the airways and reduce inflammation or congestion. However, they are always given along with inhaled corticosteroids.
- Combination inhalers: These medications already contain a combination of LABA and corticosteroid.
Reviewed by Dr Suresh S Venkita, Group Medical Director, Kauvery Hospitals
NOTE: Take medications only when prescribed by your doctors, self-medication must be avoided under any circumstances.
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