Occupational asthma

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 18 Mar 2025

Last updated: 12 Jan 2024

Occupational asthma (OA) should be suspected in all adult patients with asthma.

Occupational history may identify work-related causes. Details of work exposures should be obtained from material safety data sheets available to the patient from their workplace.

Objective evidence of asthma should be obtained from spirometry, a bronchodilator response, and/or a methacholine challenge. Tests should be performed when the patient is symptomatic and/or within days of exposure to a suspected aetiological agent.

In sensitiser-induced OA, removal from any further exposure to that agent is recommended if an immunological response to the work sensitiser is demonstrated by skin or in vitro tests.

In irritant-induced OA, preventive measures should be implemented in the workplace to reduce future exposures and episodes.

For all causes of OA, the clinician should continue treating the asthma as appropriate, assist in the initiation of any appropriate compensation claim, and consider other workers at risk.

Definition

OA is asthma caused by the workplace and may result from immunological or non-immunological stimuli.[1]

Sensitiser-induced OA is caused by immunological stimuli and develops after a latency period between first exposure and the onset of symptoms.[2][3] Irritant-induced OA (including reactive airways dysfunction syndrome) is caused by non-immunological stimuli.[4]

History and exam

Key diagnostic factors

presence of risk factors
occupational exposure to sensitising agents or irritants
symptoms of asthma that improve during holidays
initial onset of asthma symptoms during a work period

Full details

Risk factors

high-level exposure to sensitiser
atopy
genetic factors
smoking

Full details

Diagnostic investigations

1st investigations to order

spirometry
chest x-ray
skin prick testing (SPT)
non-specific bronchial hyper-responsiveness (NSBHR)
serial peak expiratory flow (PEF)

Full details

Investigations to consider

specific serum IgE assay
specific inhalation challenge (SIC)

Full details

Emerging tests

induced sputum cytology
fractional exhaled nitric oxide (FeNO)

Full details

Treatment algorithm

ACUTE

sensitiser-induced

irritant-induced

ONGOING

symptomatic asthma

Contributors

Authors

Ryan Hoy, MB BS, MOEH, FRACP

Respiratory Physician

The Alfred Hospital

Melbourne

Victoria

Australia

Disclosures

RH is an author of a reference cited in the topic.

Susan M. Tarlo, MB BS FRCP(C)

Professor of Medicine

University of Toronto

Respiratory Physician

Toronto Western Hospital

Toronto

Ontario

Canada

Disclosures

SMT has received royalties from the book Asthma in the Workplace, 5th edition, Boca Raton, FL, CRC Press, 2021. She has performed clinical patient assessments for Ontario Workplace Safety and Insurance Board, and prepared an expert document on work-related asthma and undertaken clinical file reviews for Ontario Workplace Safety and Insurance Board Appeals Tribunal. She has received a grant from Ontario Workplace Safety and Insurance Board for a systematic review of occupational COPD. SMT is an author of references cited in the topic.

Peer reviewers

Ware Kuschner, MD

Associate Professor of Medicine

Stanford University

Stanford

Staff Physician

US Department of Veterans Affairs

Palo Alto Health Care System

Palo Alto

Disclosures

WK declares that he has no competing interests.

Karin Pacheco, MD

Associate Professor of Medicine

National Jewish Medical Centre

Denver

Disclosures

KP declares that she has no competing interests.

Philip Harber, MD

Professor of Medicine

University of California

Los Angeles

Disclosures

PH declares that he has no competing interests.

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