Occupational asthma

Occupational asthma is new onset asthma or the recurrence of previously quiescent asthma directly caused by exposure to an agent at workplace. It is an occupational lung disease and a type of work-related asthma. Agents that can induce occupational asthma can be grouped into sensitizers and irritants.^[1]

Sensitizer-induced occupational asthma is an immunologic form of asthma which occurs due to inhalation of specific substances (i.e., high-molecular-weight proteins from plants and animal origins, or low-molecular-weight agents that include chemicals, metals and wood dusts) and occurs after a latency period of several weeks to years.^[1]

Irritant-induced (occupational) asthma is a non-immunologic form of asthma that results from a single or multiple high dose exposure to irritant products. It is usually develops early after exposure; however, it can also develop insidiously over a few months after a massive exposure to a complex mixture of alkaline dust and combustion products, as shown in the

Another type of work-related asthma is work-exacerbated asthma (WEA) which is asthma worsened by workplace conditions but not caused by it. WEA is present in about a fifth of patients with asthma and a wide variety of conditions at work, including irritant chemicals, dusts, second-hand smoke, common allergens that may be present at work, as well as other "exposures" such as emotional stress, worksite temperature, and physical exertion can exacerbate asthma symptoms in these patients.[4] Both occupational asthma and work-exacerbated asthma can be present in an individual.

A number of diseases have symptoms that mimic occupational asthma, such as asthma due to nonoccupational causes, chronic obstructive pulmonary disease (COPD), irritable larynx syndrome, hyperventilation syndrome, hypersensitivity pneumonitis, and bronchiolitis obliterans.

Signs and symptoms

Like other types of asthma, it is characterized by airway inflammation, reversible airways obstruction, and bronchospasm, but it is caused by something in the workplace environment.

The following tables show occupations that are known to be at risk for occupational asthma. The main reference is the Canadian Centre for Occupational Health and Safety.^[12]

Diagnosis

To diagnose occupational asthma it is necessary to confirm the symptoms of asthma and establish the causal connection with the work environment. Various diagnostic tests can be used to aid in diagnoses of work-related asthma.^{[1][3][13][14]}

A spirometer is a device used to measure timed expired and inspired volumes, and can be used to help diagnose asthma.

A

Specific inhalation challenges test consist of exposing the subjects to the suspected occupational agent in the laboratory and/or at the workplace and assessing for asthma symptoms as well as a reduction in FEV₁.^[3][16]

Other tests such as the

Asthma symptoms and airway hyperresponsiveness can persist for several years after removal from the offending environment.[13] Thus, early restriction from exposure to the trigger is advisable. Completely stopping exposure is more effective treatment than reducing exposure, but not always feasible.^[8]

Management

Medication

Medications used for occupational asthma are similar to those used for other types of asthma such as short-acting

Occupational asthma is one of the most common occupational lung disease. Approximately 17% of all adult-onset asthma cases are related to occupational exposures.[20] About one fourth of adults with asthma have work-exacerbated asthma.^[4] Patients with work-related asthma are more likely to experience asthma attacks, emergency room visits, and worsening of their asthma symptoms compared with other adult asthma patients.^[20]

Society and culture

Compensation

When a person is diagnosed with occupational asthma, it can result in serious socio-economic consequences not only for the workers but also for the employer and the healthcare system because the worker must change positions.^[21] The probability of being re-employed is lower for those with occupational asthma compared to those with normal asthma. The employer not only pays compensation to the employee, but will also have to spend a considerable amount of time and energy and funds for hiring and training new personnel.^[22][23] In the United States, it was estimated that the direct cost of occupational asthma in 1996 was $1.2 billion and the indirect cost $0.4 billion, for a total cost of $1.6 billion. In most cases, the employer could have saved more money by adhering to safety standards rather than causing employees to become injured.^[24]

However, this can entail severe socio-economic consequences for the worker as well as the employer due to loss of job, unemployment, compensation issues, medical expenditures, and hiring and re-training of new personnel.^[21]

See also

• Chronic obstructive pulmonary disease (COPD)
• Specific inhalation challenge
• Occupational safety and health
• National Institute of Occupational Safety and Health (NIOSH)
• Labor rights

References