How Is Occupational Asthma Diagnosed?

Have you been experiencing breathing problems at work? If so, you may be wondering how occupational asthma is diagnosed. This article aims to shed light on the different methods and tests used to diagnose this condition. By understanding the diagnostic process, you can seek proper medical assistance and take necessary steps to protect your respiratory health in the workplace.

Table of Contents

Medical history and symptom evaluation

Topical questions

When diagnosing occupational asthma, the first step is to gather a detailed medical history. This includes asking topical questions to understand the individual’s job, workplace, and potential exposures to respiratory irritants or allergens. The aim is to identify any occupational triggers that may be causing or exacerbating the symptoms.

Work exposure and symptoms

Understanding the individual’s work exposure is crucial in diagnosing occupational asthma. This involves assessing the nature of their job, the specific agents they may come into contact with, and the duration and intensity of exposure. It is important to evaluate if there is a temporal relationship between exposure to certain substances at work and the onset or worsening of respiratory symptoms.

Timing of symptoms

Determining the timing of symptoms is essential in diagnosing occupational asthma. Assessing whether symptoms improve on weekends, holidays, or during extended periods away from work can provide valuable insight. If symptoms consistently worsen during the workweek and improve during time away from work, it suggests a potential work-related trigger for asthma symptoms.

Symptom variations

Another important aspect of diagnosing occupational asthma is evaluating variations in symptoms throughout the day or week. Assessing if symptoms are worse during specific work tasks or in certain areas of the workplace can help identify potential asthma triggers. Variations in symptoms based on work shifts or exposures to specific substances can provide further clues in the diagnostic process.

Family history

Considering an individual’s family history is vital in determining the cause of asthma symptoms. It helps to identify any genetic predisposition to asthma or allergies, as well as potential shared environmental exposures. A family history of asthma or allergies can increase the likelihood of occupational asthma as a diagnosis.

Physical examination

Auscultation of the chest

During the physical examination, auscultation of the chest can provide important information about the individual’s respiratory health. Abnormal breath sounds, such as wheezing or crackles, may indicate the presence of asthma or other respiratory conditions. The intensity and location of these abnormal sounds can help guide further investigation and management.

Measurement of peak expiratory flow rate (PEFR)

Assessing the peak expiratory flow rate (PEFR) is a useful tool in diagnosing occupational asthma. PEFR measures the maximum speed at which air can be exhaled and can indicate the presence of airway obstruction. Comparing PEFR measurements before and after exposure to occupational triggers can help determine if there is a work-related component to the individual’s asthma symptoms.

Skin prick tests

Skin prick tests are commonly used to diagnose allergic asthma, a subtype of occupational asthma. These tests involve placing small amounts of potential allergens on the skin and assessing for an allergic reaction. If an individual has a positive skin prick test to a specific occupational allergen, it suggests that exposure to that substance may be contributing to their asthma symptoms.


Spirometry is a standard diagnostic test used to assess lung function. It measures the amount of air an individual can forcefully exhale in one second (FEV1) and the total amount of air exhaled (FVC) in one breath. Comparing spirometry results before and after exposure to potential work-related triggers can help determine if there is an occupational component to the individual’s asthma symptoms.

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Chest X-rays

Chest X-rays are typically done to rule out other respiratory conditions or to assess the severity of asthma. While they may not directly diagnose occupational asthma, they can help identify any abnormalities in the lungs or rule out other potential causes for the individual’s symptoms.

Diagnostic tests

Serial peak expiratory flow measurements

Serial peak expiratory flow measurements involve regular monitoring of an individual’s peak expiratory flow rate (PEFR) over time. This can help identify any patterns or trends in PEFR that may indicate occupational asthma. If there is a consistent decline in PEFR associated with periods of work exposure, it suggests a work-related trigger for asthma symptoms.

Methacholine challenge test

A methacholine challenge test is a diagnostic test used to assess airway hyperresponsiveness. It involves inhaling increasing doses of methacholine, a substance that causes the airways to contract. If an individual’s airways become hyperreactive and constrict at lower levels of methacholine, it suggests the presence of asthma. This test can be particularly useful in diagnosing occupational asthma when other tests may not provide definitive results.

Specific inhalation challenge

A specific inhalation challenge is considered the gold standard for diagnosing occupational asthma. It involves exposing the individual to a specific occupational agent in a controlled environment and assessing for the development of asthma symptoms. If symptoms and lung function changes occur during or shortly after exposure to the specific agent, it confirms the diagnosis of occupational asthma.

Bronchial provocation test

Similar to the specific inhalation challenge, a bronchial provocation test assesses airway reactivity and can help diagnose occupational asthma. It involves exposing the individual to a substance that causes the airways to constrict, such as histamine or exercise. If the individual experiences a significant decline in lung function or develops asthma symptoms during the test, it suggests the presence of asthma.

Blood tests (immunoglobulin E levels)

Blood tests, specifically measuring immunoglobulin E (IgE) levels, can be helpful in diagnosing allergic asthma. Elevated IgE levels suggest an immune response to specific allergens. If an individual has elevated IgE levels to certain occupational allergens, it supports the diagnosis of occupational asthma caused by allergic sensitization.

Fractional exhaled nitric oxide test

The fractional exhaled nitric oxide (FeNO) test measures the concentration of nitric oxide in the breath, which can indicate airway inflammation. Elevated FeNO levels are associated with asthma and can be indicative of occupational asthma. This test is particularly useful for monitoring and assessing the effectiveness of treatment in individuals with asthma.

Occupational history and exposure assessment

Detailed work history

Obtaining a detailed work history is crucial in evaluating occupational asthma. It involves gathering information about the individual’s past and current jobs, including job titles, tasks performed, and the materials or substances they come into contact with. Understanding the nature of the work is essential in identifying potential occupational triggers for asthma symptoms.

Identification of potential asthma-related agents

Identifying potential asthma-related agents in the workplace is a critical step in diagnosing occupational asthma. This involves compiling a list of substances that the individual may be exposed to, including chemicals, dust, fumes, or other respiratory irritants. Additionally, it is important to determine if there are any known associations between these substances and the development of asthma.

Exposure monitoring

Exposure monitoring involves quantifying and assessing the individual’s exposure to potential asthma triggers in the workplace. This can be done through personal air sampling, where the individual wears a sampling device to measure their personal exposure to specific substances. Exposure monitoring helps to determine the actual levels of exposure and the potential risk to the individual’s respiratory health.

Review of material safety data sheets (MSDS)

Reviewing material safety data sheets (MSDS) is an essential part of assessing occupational exposure. MSDS provide information about the potential hazards of substances used in the workplace, including their chemical composition, health effects, and recommended safety precautions. Examining MSDS helps to identify potential respiratory irritants and allergens that may be contributing to the individual’s asthma symptoms.

Workplace visits

Conducting workplace visits can provide valuable insight into the individual’s work environment and potential exposures. This involves observing the workplace, noting any ventilation systems, identifying potential sources of respiratory irritants or allergens, and speaking to coworkers about their experiences with respiratory symptoms. Workplace visits help to corroborate the information obtained through the individual’s medical history and exposure assessment.

Differential diagnosis

Allergic asthma

Allergic asthma is a subtype of occupational asthma caused by exposure to allergens in the workplace. It is diagnosed when an individual has a positive skin prick test or elevated IgE levels to specific occupational allergens. Allergic asthma is characterized by airway inflammation triggered by the immune system’s response to these allergens.

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Non-occupational asthma

Non-occupational asthma refers to asthma that is not caused or worsened by workplace exposures. It may be triggered by other factors such as allergens, respiratory infections, exercise, or stress. Differentiating non-occupational asthma from occupational asthma is crucial in ensuring appropriate treatment and management strategies are implemented.

Chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a chronic lung condition characterized by inflammation and structural changes in the airways. COPD is typically associated with long-term exposure to cigarette smoke or other harmful substances, such as biomass fuel or occupational dusts. Distinguishing COPD from occupational asthma is important for tailored management and treatment plans.

Reactive airways dysfunction syndrome (RADS)

Reactive airways dysfunction syndrome (RADS) is a type of asthma that develops following a single exposure to a high concentration of irritating substances. It is typically characterized by a sudden onset of asthma symptoms shortly after the exposure. Distinguishing RADS from occupational asthma is important as the treatment and prognosis may differ.

Vocal cord dysfunction

Vocal cord dysfunction (VCD) is a condition that can mimic asthma symptoms. It involves the abnormal movement of the vocal cords during breathing, leading to airflow restriction. VCD is often triggered by emotional stress or exercise and does not respond to standard asthma medications. It is essential to differentiate VCD from occupational asthma to ensure appropriate management.

Collaborative assessment

Occupational health specialists

Occupational health specialists play a vital role in the diagnosis and management of occupational asthma. They have expertise in evaluating workplace exposures, conducting exposure assessments, and implementing control measures. Occupational health specialists work closely with other healthcare professionals to ensure comprehensive care and guidance in preventing further exposure to occupational triggers.

Respiratory physicians

Respiratory physicians are essential in diagnosing and managing occupational asthma. They are skilled in interpreting diagnostic tests, such as spirometry and bronchial provocation tests, and can provide expertise in treating asthma symptoms. Respiratory physicians collaborate with occupational health specialists to determine the best course of action in managing occupational asthma.


Allergists/Immunologists play a crucial role in diagnosing and managing allergic asthma, a subtype of occupational asthma. They are trained in conducting skin prick tests, interpreting IgE levels, and identifying specific allergens. Allergists/Immunologists collaborate with respiratory physicians and occupational health specialists to develop personalized treatment plans for individuals with occupational asthma caused by allergen exposure.

Primary care physicians

Primary care physicians play an important role in the early identification and referral of individuals with suspected occupational asthma. They conduct initial assessments, provide initial treatment, and refer individuals to appropriate specialists for further evaluation and management. Primary care physicians work collaboratively with other healthcare professionals to ensure comprehensive care and support for individuals with occupational asthma.

Other medical specialists

Depending on the specific circumstances and underlying conditions, other medical specialists may be involved in the collaborative assessment of occupational asthma. This may include specialists such as pulmonologists, allergists, otolaryngologists, and psychiatrists. The collaboration between different medical specialists ensures a multidisciplinary approach in managing and treating occupational asthma.

Follow-up and monitoring

Regular monitoring of symptoms

Regular monitoring of symptoms is essential in managing occupational asthma. It involves keeping track of the frequency, severity, and duration of asthma symptoms. By regularly assessing symptoms, healthcare professionals can identify trends or triggers and adjust treatment plans accordingly.

Periodic lung function tests

Periodic lung function tests, such as spirometry, are crucial in monitoring the progress and severity of occupational asthma. These tests measure lung capacity and the ability to exhale air forcefully, providing objective measurements of lung function. Repeat spirometry tests help track any changes in lung function over time and guide treatment decisions.

Continued exposure assessment

Continued exposure assessment is necessary in managing occupational asthma. It involves regular reassessment of workplace exposures and monitoring for any changes in occupational triggers. By understanding the current work environment and exposure levels, healthcare professionals can make informed decisions regarding work modifications or adjustments, if necessary.

Impact on quality of life

Assessing the impact of occupational asthma on an individual’s quality of life is an important part of follow-up and monitoring. This involves evaluating the physical, emotional, and social aspects of daily functioning, as well as any limitations imposed by asthma symptoms. Addressing the impact on quality of life helps healthcare professionals tailor treatment and management strategies to meet the individual’s specific needs.

Occupational changes or adjustments

In some cases, occupational changes or adjustments may be necessary to manage occupational asthma effectively. This can include modifying job tasks or the work environment to reduce exposure to respiratory irritants or allergens. Collaboration between healthcare professionals, occupational health specialists, and employers is crucial in implementing these changes while ensuring the individual’s continued employment and well-being.

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Treatment and management strategies

Avoidance or reduction of workplace exposure

Avoidance or reduction of workplace exposure is a key component in managing occupational asthma. This involves implementing control measures to minimize or eliminate exposure to respiratory irritants or allergens. Strategies may include ventilation improvements, personal protective equipment (PPE) utilization, and job modifications to reduce contact with asthma triggers.


Pharmacotherapy is a fundamental aspect of managing occupational asthma. This includes the use of bronchodilators to relieve acute symptoms and prevent exacerbations, as well as anti-inflammatory medications to reduce airway inflammation. Individual treatment plans may include inhaled corticosteroids, long-acting beta-agonists, leukotriene modifiers, or other medications tailored to the individual’s specific needs.


Immunotherapy, particularly allergen immunotherapy, may be considered in cases of occupational asthma caused by specific allergens. This involves gradually exposing the individual to increasing amounts of the allergen to desensitize the immune system. Immunotherapy can help reduce allergic reactions and improve asthma control in individuals with occupational asthma caused by allergic sensitization.

Education and patient counseling

Education and patient counseling are integral in managing occupational asthma. Providing individuals with information about their condition, its triggers, and ways to manage symptoms empowers them to take an active role in their own health. Healthcare professionals can offer guidance on recognizing symptoms, managing triggers, and implementing self-care strategies to optimize asthma control and reduce workplace exposures.

Occupational rehabilitation

Occupational rehabilitation programs can be beneficial in managing occupational asthma. These programs focus on helping individuals develop skills and strategies to adjust to their condition in the workplace. Occupational rehabilitation may involve providing education, work modifications, or vocational counseling to ensure individuals can continue to work safely and effectively while managing their asthma.

Workplace interventions and control measures


Elimination of respiratory irritants or allergens is the most effective measure to prevent occupational asthma. Whenever possible, removing the causative agents from the workplace entirely eliminates the risk of further exposure. This can be achieved through changes in production methods, use of alternative substances, or adoption of new technologies.


When elimination is not feasible or practical, substitution of harmful substances with less hazardous alternatives can reduce the risk of occupational asthma. This involves replacing or substituting substances or materials with less allergenic or less irritant properties. Substitution strategies aim to minimize the exposure to substances that can trigger or exacerbate asthma symptoms.

Engineering controls

Engineering controls involve modifying the work environment to reduce the levels of respiratory irritants or allergens. Examples include improving ventilation systems, implementing local exhaust ventilation, or installing barriers to prevent or contain the spread of hazardous substances. Engineering controls are an effective way to minimize exposure and protect workers from developing or worsening occupational asthma.

Administrative controls

Administrative controls refer to changes in work practices or policies to reduce exposure to respiratory irritants or allergens. This can include modifying work schedules, providing regular breaks, implementing rotation systems, or establishing protocols for safe material handling. Administrative controls aim to minimize the risk of exposure, protect workers, and ensure compliance with safety guidelines and regulations.

Personal protective equipment (PPE)

Personal protective equipment (PPE) is an important measure in preventing occupational asthma when other control measures are insufficient. PPE includes items such as respirators, gloves, goggles, or protective clothing that workers use to minimize their exposure to hazardous substances. Proper selection, training, and use of PPE can effectively reduce the risk of occupational asthma and protect workers’ respiratory health.

Prevention and education

Workplace education and training programs

Workplace education and training programs are essential in preventing occupational asthma. These programs aim to increase awareness and knowledge among workers about respiratory hazards, asthma symptoms, and preventive measures. Providing education on safe work practices, proper use of protective equipment, and early recognition of symptoms empowers workers to protect their respiratory health.

Enhanced ventilation systems

Enhanced ventilation systems in the workplace can help reduce exposure to respiratory irritants or allergens. Properly designed ventilation systems effectively remove or dilute airborne contaminants, minimizing the risk of developing occupational asthma. Regular maintenance and inspections ensure the continued effectiveness of these systems in protecting workers’ respiratory health.

Regular monitoring of air quality

Regular monitoring of air quality is crucial in preventing and managing occupational asthma. This involves measuring and assessing the levels of respiratory irritants or allergens in the workplace environment. By monitoring air quality, employers can identify any changes or exceedances of safe limits and implement appropriate measures to reduce exposure.

Safe work practices

Implementing safe work practices is essential in preventing occupational asthma. This includes following established protocols for handling hazardous substances, practicing good hygiene, and using protective equipment correctly. Encouraging a safety culture in the workplace promotes shared responsibility for respiratory health and reduces the risk of developing occupational asthma.

Prompt reporting and intervention

Prompt reporting and intervention are crucial in preventing the progression of occupational asthma. Encouraging workers to report any respiratory symptoms or concerns promptly allows for early intervention and management. Employers should implement mechanisms for reporting and take immediate action to address any potential hazards or exposures identified.

In conclusion, diagnosing occupational asthma requires a thorough assessment of an individual’s medical history, symptom evaluation, and physical examination. Diagnostic tests, such as serial peak expiratory flow measurements, specific inhalation challenges, and blood tests, are used to confirm the diagnosis. Collaborative assessment involving occupational health specialists, respiratory physicians, allergists, and primary care physicians is crucial in managing and treating occupational asthma. Follow-up and monitoring, treatment and management strategies, workplace interventions, and prevention and education are all essential components in the comprehensive care of individuals with occupational asthma. By identifying and reducing workplace exposures and ensuring proper treatment and support, the goal is to improve the quality of life and respiratory health of individuals with occupational asthma.