Severe Asthma ToolkitSevere Asthma Toolkit
HomeAboutSpecific PopulationsRegistriesContributorsContact
Twitter
  • What is Severe Asthma?
    • Overview
    • Definition
    • Prevalence & Burden
    • Pathophysiology
    • Symptoms
    • Severe Asthma Attacks / Exacerbations / Flare-ups
    • Asthma Phenotypes
  • Diagnosis & Assessment
    • Overview
    • Diagnosis Overview
    • Assessment Overview
    • Lung Function Assessments
    • Questionnaires
    • Allergy Assessments
    • Phenotyping
    • Bronchoscopy
    • Imaging
    • Occupational Asthma
  • Management
    • Overview
    • Asthma Education
      • About Severe Asthma
      • Asthma Pathophysiology
      • Medications Education
      • Self-Monitoring
      • Triggers
      • Review
    • Written Action Plans
    • Adherence
    • Inhaler Technique
    • Physical Activity & Exercise
    • Interdisciplinary Approach & Multidimensional Assessment
    • Referral
  • Medications
    • Overview
    • Relievers
    • Preventers / Controllers
    • Add-on Therapies
    • Monoclonal Antibodies
    • Bronchial Thermoplasty
  • Co-Morbidities
    • Overview
    • Pulmonary & Upper Airways
      • Allergic & Non-Allergic Rhinitis
      • Chronic Rhinosinusitis
      • Dysfunctional Breathing
      • Vocal Cord Dysfunction
      • Chronic Obstructive Pulmonary Disease
      • Bronchiectasis
      • Obstructive Sleep Apnoea
    • Extra-Pulmonary
      • Obesity
      • Anxiety & Depression
      • Gastro-oesophageal Reflux Disease (GORD)
      • Osteoporosis
      • Cardiovascular Disease & Metabolic Disease
  • Living with Severe Asthma
    • Overview
    • Daily Symptom Burden
    • Mental & Emotional Health
    • Intimacy & Relationships
    • Self-Management Support
    • Medication Use & Costs
    • Experience of Care
    • Experience of Asthma Attacks
    • Prognosis
  • Establishing a Clinic
    • Overview
    • Set-up
    • Staffing & Multidisciplinary Team Approach
    • Facilities
    • Delivery Approach
    • Tailored Referrals
    • Evaluation
    • Opportunities for Training & Research
    • Barriers & Hurdles
  • Paediatrics
    • Overview
    • Management in Paediatrics
    • Assessment in Paediatrics
    • Alternative Diagnosis & Co-Morbidities in Paediatrics
    • Psychosocial Issues in Paediatrics
    • Medications in Paediatrics
    • Asthma in the Adolescent Population
  • Resources
    • Overview
    • Clinic Recommendations
    • Infographics
    • Asthma Assessment Resources
    • Systematic & Multidimensional Assessment Resources
      • Airway Components
      • Comorbidity Components
      • Risk Factor Components
    • Translation & Implementation
    • Case Studies
    • Presentations
    • Videos
    • Relevant Links
    • Key References

Occupational Asthma

Home Diagnosis & Assessment Occupational Asthma
man spray painting depicting an example of Occupational Asthma

Occupational Asthma

Work-related asthma includes both asthma that has been caused by work (occupational asthma) and asthma that is exacerbated by work (work-exacerbated asthma). Work-related asthma is a common occupational lung disease. International estimates indicate that up to 25% of adults have work-related asthma and 15% of adult-onset asthma may be caused by hazardous occupational exposures (Hoy et al. 2017).

Work-related asthma tends to be more severe than non-work related asthma, with the potential for higher higher medication use, reduced asthma control, more rapid decline in lung function and greater socio-economic impact (Hoy et al. 2017). Occupational exposure to a range of compounds is associated with severe asthma attacks (Henneberger et al. 2015; Kim et al. 2016). However, to our knowledge no studies have specifically investigated links between work-related asthma and severe, treatment-refractory asthma.

Occupational asthma can be subdivided into sensitiser-induced and irritant-induced subtypes. Approximately 90% of cases are classified as sensitiser-induced occupational asthma. Sensitisers are agents that induce an immunological response after repeated exposures. Over 300 workplace agents have been described as causes of occupational asthma (see list here). Following development of sensitiser-induced occupational asthma, exposure to the inciting sensitiser will cause an asthma response, even at a low level of exposure. Irritant-induced occupational asthma is non-immune, resulting from exposure of the airways to irritant substances, typically at a high level such as following an industrial accident.

Sensitisers can be subdivided into 2 types:

  • High molecular weight – includes proteins, with the most common being wheat flour, animal antigens and wood dust. Typically stimulate allergic immune responses, with activation of Type-2 and eosinophilic airway inflammation. For more on pathophysiology click here
  • Low molecular weight – includes chemicals, such as diisocyanates, and wood dust. The immune response is less understood but can contribute to eosinophilic or neutrophilic airway inflammation.

Risk factors for developing occupational asthma include:

  • Occupational exposure to a respiratory sensitiser, in particular the level of exposure
  • Pre-existing atopy
  • Genetic pre-disposition
  • Smoking status
  • Occupational rhinitis, which often precedes symptoms of occupational asthma

Diagnosis:

Diagnosis of occupational asthma requires objective confirmation of the diagnosis of asthma and demonstration of an association between asthma and the workplace. The diagnosis should be made as early as possible because ongoing exposure to the causative agent at the workplace is likely to result in asthma becoming more severe, leading to rapid lung function decline (Anees et al. 2006). The diagnosis must be made accurately due to the potential negative socioeconomic implications of the management of the condition, therefore should be confirmed by a specialist with expertise in occupational asthma.

Diagnosis of occupational asthma requires a combination of investigations:

Confirmation of asthma diagnosis
Clinical history and screening questions
Lung function assessment and monitoring
Allergy testing
Specific inhalation challenge
Workplace challenge
Confirmation of asthma diagnosis

An initial confirmation of an asthma diagnosis is required. For more information see Diagnosis & Assessment Overview

Clinical history and screening questions

All patients with asthma should be questioned about their work, but in particular if they have new onset or difficult to control asthma. Patients should be asked if their symptoms improved when they are away from the workplace such as on holidays and worsen on their return to work. Patients should be questioned about their occupational history and exposure to potential sensitisers or irritants at their workplace. Safety Data Sheets (SDS) may be accessed to provide information on the constituent of products found at workplaces, which can be useful to identify potential sensitisers.

Lung function assessment and monitoring

Lung function assessment and monitoring can be utilised to identify an association between asthma and work exposures. Peak expiratory flow (PEF) monitoring (4 measurements / day) including periods at work and off work is commonly used to document associations between lung function and time at work. Note that, bronchial provocation (methacholine challenge) tests can be normal, if the patient is not currently exposed in the workplace, therefore performance of testing soon after consideration of the diagnosis is important. A negative methacholine challenge can effectively rule out occupational asthma in symptomatic, actively exposed patients, and should lead to consideration of other causes of work-associated respiratory symptoms. Serial measurements of bronchial hyperreactivity or airway inflammation, during periods of work versus off-work periods (after holiday) can improve diagnosis specificity. For more information see Diagnosis & Assessment – Lung Function Assessments

Allergy testing

Allergy testing may be useful to identify a specific sensitiser. Specific allergy testing is available for many high molecular weight sensitisers such as wheat flour, although specificity is quite low. A positive finding indicates sensitisation, but not necessarily occupational asthma. For more information see Diagnosis & Assessment – Allergy Assessments

Specific inhalation challenge

Specific inhalation challenge can be useful if other investigations are equivocal or negative for occupational asthma, or identification of a specific sensitiser is necessary. This approach is not currently available in Australia.

Workplace challenge

A workplace challenge may be useful if no causal agent is identified in other investigations, the exposure cannot be recreated in the laboratory or a specific inhalation challenge is negative but occupational asthma is considered likely. This assessment is very rarely performed.

Management:

Once the diagnosis has been confirmed by a specialist, pharmacological management of occupational asthma includes a stepped approach to treatment based on asthma management guidelines.

The most important aspect of the management of sensitiser-induced occupational asthma is avoidance of the sensitiser. In some circumstances this may require relocation of the worker within the workplace or even a change of workplace. This process may require involvement of the workers compensation system. If a worker continues to work with ongoing exposure to the sensitiser they require close monitoring including regular performance of spirometry. Use of respiratory protection alone has not been demonstrated to provide sufficient protection for workers with occupational asthma.

Identification of one worker with occupational asthma indicates that other workers are at risk and there are likely to have been failings in the identification and control of respiratory hazards at the workplace. If the patient consents, there should be communication with the employer regarding the diagnosis and implementation of a review of hazard control measures.

To watch a seminar on occupational asthma on the Centre of Excellence in Severe Asthma website, click here.

Prognosis:

For workers with sensitiser-induced occupational asthma, complete avoidance of the exposure is often necessary to improve symptoms (BMJ Best Practice). Ongoing exposure to the sensitiser is likely to lead to a progressive worsening of asthma outcomes. Improvement is generally seen within 2 years of removing the exposure, but can take up to 10 years. People with an early diagnosis of occupational asthma and shorter durations of sensitiser exposure are more likely to have improved outcomes.

For workers with irritant-induced occupational asthma, symptoms may resolve within months to year or may persist long-term. If affected people do return to work, ongoing monitoring is important to manage disease exacerbations.

However, to our knowledge no studies have specifically reported on outcomes for people with work-related asthma and severe, treatment-refractory asthma, so prognosis in this population remains unclear.

Additional Resources:

  • Australian Asthma Handbook – includes guidance on work-related asthma, including occupational asthma

  • Work-Related Asthma Web page – developed by the the Lung Health Foundation (Canada), this web page aims to people with asthma about the possible effects of workplaces on their asthma
  • Oasys and Occupational Asthma Website – run by the Oasys research group, part of the Midland Thoracic Society, UK. This website provides information on occupational asthma and the Oasys software programme which can be used to support the diagnosis of occupational asthma
Previous
Management

Last Updated on October 3, 2022

Generic selectors
Exact matches only
Search in title
Search in content
Search in posts
Search in pages
Filter by Categories

More results...

  • Overview
  • Diagnosis Overview
  • Assessment Overview
  • Lung Function Assessments
  • Questionnaires
  • Allergy Assessments
  • Phenotyping
  • Bronchoscopy
  • Imaging
  • Occupational Asthma

We want to know who accesses the Severe Asthma Toolkit and how it is used. Please complete our survey.

Responses will inform the continued development of the Severe Asthma Toolkit and future translation and implementation activities. Any feedback you provide will be greatly appreciated.

Complete Survey

  • Website Terms of Use
  • Website Survey
© Copyright 2018    CRICOS Provider Number 00109J    The University of Newcastle, Australia