Certain occupations can put lung health at risk, particularly in manufacturing and construction, where workers may be exposed to respiratory hazards such as silica. Measures can be put in place to protect employees’ lung health and promote a safer working environment. Lung health surveillance is a process which assesses an employee’s respiratory health to prevent lung disease from developing when their work environment might be a contributing factor.
The purpose is to maintain and protect the health and safety of employees, assess the effectiveness of existing control measures and help to identify areas where there might still be an impact on an employee’s lung health. It can ensure that any potential lung diseases are detected as early as possible. Some elements of lung health surveillance is required by law, a key piece of UK legislation is COSHH (Control of Substance, Hazardous to Health Regulations 2002) where employers by law must prevent or adequately control exposure to hazardous substances if there is known risk associated with the job role. According to the Health and Safety Executive (HSE) health surveillance is necessary when:
- There is a disease associated with the substance in use
- It is possible to detect the disease or adverse change and reduce risk of further harm
- The conditions in the workplace make it likely that the disease will appear
Overall, lung health surveillance results should be fed into the organisation’s risk management system. If work related lung disease is detected due to exposure to potentially harmful substances, risk assessment and control measures need to be reviewed. It should be noted that lung health surveillance is not for diagnosing lung disease but supports screening and clinical evaluations.
What does Lung Health Surveillance Involve?
An initial risk assessment is a crucial first step in lung health surveillance. This involves identifying workplace respiratory hazards such as wood dust, isocyanates, welding fumes and laboratory animal allergens. This is followed by an individual risk assessment, which considers personal factors including lifestyle and any pre-existing respiratory disease. The HSE provides standardised respiratory questionnaires that support the identification of relevant symptoms. Objective assessment is achieved through lung function testing, most commonly Spirometry, which measures the volume of air exhaled following a full inhalation. The aim of workplace spirometry is to identify workers who may require further investigation for potential respiratory disease.
In occupational health practice, the main spirometry parameters reported are, Vital Capacity (VC) , Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1) and FEV1/FVC ratio. These parameters provide valuable insight to an employee’s lung health, and are used identify obstructive and restrictive patterns of respiratory impairment. In situations where Spirometry is not accessible or where a specific disease such as Occupational Asthma is suspected, Serial Peak Expiratory Flow (PEF) measurements can also be obtained.
It is recommended that occupational health professionals interpret the health surveillance results for both individuals and groups of similarly exposed workers. This can confirm whether the risk assessment needs to be revised, trigger a review of exposure control and where necessary move workers to alternative roles. The frequency of lung health surveillance will vary but usually there is an initial baseline measurement obtained at the start of employment, ongoing annual testing and exit health surveillance.
Interpreting Spirometry
Planning and preparation are essential components of lung health surveillance. A clear process should be in place for managing workers who report respiratory symptoms or present with abnormal lung function results. This should outline when and how workers are referred for further assessment to their General Practitioner or an Occupational Health Practitioner. It should also address how workers with diagnosed work-related lung disease will be managed. This may include exposure reduction or redeployment to alternative roles. Both the worker and the employer should be fully informed of this process throughout.
Consistency in obtaining reliable and accurate lung function results over time depends on several factors. These include ensuring spirometry tests are technically acceptable and repeatable, maintaining accurate and well-calibrated equipment, and ensuring healthcare professionals conducting the tests are competent. Evidence-based interpretation is essential to ensure meaningful and valid spirometry results.
Spirometry interpretation involves the use of predictive reference equations to generate predicted values that represent average lung function for individuals with similar demographic characteristics. Interpretation requires comparison of measured values obtained on the day of testing with these predicted values. Historically, spirometry has been interpreted using percentage predicted values, with normal lung function defined as an FEV₁/FVC ratio greater than 70% and FEV₁ and FVC values greater than 80% predicted. However, this fixed-ratio approach does not account for normal variability across populations. It may fail to detect abnormalities in younger individuals and may over-diagnose lung disease in older individuals.
The ATS/ERS and Global Lung Function Initiative (GLI) recommend using the lower limit of normal (LLN), defined as a Z-score of −1.64, as this method provides greater statistical precision and accounts for population variability. Despite this, occupational health regulations and surveillance programmes often specify the use of percentage predicted values, and these may still be reported for regulatory or administrative purposes. When spirometry is performed in the workplace, assessment of absolute values and longitudinal trends over time is crucial, as this can help identify patterns such as excessive decline in FEV₁.
Spirometry results can be categorised into distinct patterns. A normal pattern is identified when all reported parameters have Z-scores greater than −1.64. An obstructive pattern is indicated by a reduced FEV₁/FVC ratio with a Z-score less than −1.64, often accompanied by a reduced FEV₁. A restrictive pattern is suggested by a normal FEV₁/FVC ratio with reduced FEV₁ and FVC values, both with Z-scores less than −1.64.
What else could it be?
Normal Spirometry and Symptomatic Individuals
Spirometry interpretation is not always straightforward. Some workers may present with normal spirometry results while still reporting respiratory symptoms. A common misconception is that normal spirometry means the individual is fine. However, research has shown that normal spirometry does not rule out underlying respiratory disease, and reported symptoms continue to carry important prognostic value.
Evidence suggests that chronic respiratory symptoms are associated with adverse outcomes even in individuals with normal spirometry. Colak et al. (2019) demonstrated a positive dose–response relationship between the number of respiratory symptoms and future health risks. Their findings showed that individuals with chronic respiratory symptoms had higher rates of future respiratory hospitalisations and increased mortality, despite having normal spirometry and no previously diagnosed airway disease.
There are several clinical scenarios in which an individual may be symptomatic despite normal spirometry. One example is early airway disease, which refers to subtle structural changes in the peripheral small airways that may not yet be detected by standard spirometry. This may present with early symptoms of COPD, such as chronic cough or mild breathlessness. Early identification is important, as timely intervention may slow or prevent disease progression. Smoking and occupational exposures are common contributing factors. Asthma may also present with normal spirometry due to its variable nature; if testing occurs when triggers are absent, airflow obstruction may not be evident.
Another consideration is preserved ratio impaired spirometry (PRISm), a lung function pattern characterised by a normal FEV₁/FVC ratio with a reduced FEV₁. This differs from classical airflow obstruction, which is defined by a reduced FEV₁/FVC ratio. Individuals with PRISm typically have reduced overall lung volumes and may be further classified as restrictive (reduced FVC) or non-restrictive (normal FVC). PRISm is commonly associated with chronic respiratory symptoms and has been linked to smoking, obesity, cardiovascular disease, and an increased risk of progression to COPD.
These conditions highlight the importance of evaluating reported symptoms alongside spirometry results and reinforce that spirometry should not be used in isolation when assessing a worker’s respiratory health.
Abnormal Spirometry and Asymptomatic Individuals
It is important for occupational health practitioners to recognise that the absence of reported symptoms does not necessarily indicate low risk of disease or good respiratory health. In asymptomatic individuals, spirometry may reveal early or “silent” disease, with alterations in lung physiology occurring before symptoms develop. Research has shown that asymptomatic airflow obstruction is associated with an increased future risk of COPD, cardiovascular disease, and other adverse health outcomes.
Abnormal spirometry in asymptomatic workers should be interpreted cautiously within the context of lung health surveillance. While abnormal spirometry may be suggestive of disease, it is not always pathological. In some individuals, abnormal results may reflect normal physiological variation rather than disease. One recognised example is dysanapsis, a variation that can occur during puberty where lung parenchymal growth outpaces airway calibre. This results in airways that do not scale proportionally with lung volume and may produce an obstructive spirometry pattern in an otherwise healthy, asymptomatic individual. Dysanapsis is lifelong, non-progressive, and not necessarily pathological. In contrast, exposure-related lung impairment is typically progressive and preventable, highlighting the importance of longitudinal trend analysis rather than reliance on isolated measurements.
Other physiological factors may also influence spirometry results. For example, individuals with a large forced vital capacity (FVC) may have a normal FEV₁ but relatively reduced compared to the FVC resulting in a reduced FEV₁/FVC ratio. On the other hand, some workers may adapt to functioning with reduced lung capacity over time and under-report symptoms, making it difficult for them to distinguish between normal and abnormal respiratory function.
Non-physiological factors should also be considered. Workplace culture, fear of negative consequences, or poor organisational planning may discourage workers from reporting symptoms, particularly if declining lung function could lead to job changes or loss of employment. Additionally, individuals who remain under health surveillance may represent a selected population who have tolerated workplace exposures to date. In these cases, the absence of symptoms may reflect survivorship rather than true safety.
In Summary
Being aware of the nuances of spirometry is essential in the evaluation and management of workers’ lung function, to supports effective lung health surveillance. However, spirometry should not be used in isolation. A comprehensive approach must also consider individual risk assessments, workers’ reported symptoms, lifestyle factors, and an understanding of when to refer for further advice or investigation. Consistency in workplace health surveillance and in the collection of lung function tests is vital to ensure reliable results and accurate trend data over time. Companies and Occupational Health Practitioners should therefore avoid stagnant practices and continually review and improve their lung health surveillance processes to ensure best practice and worker safety.
References
The Control of Substances Hazardous to Health Regulations 2002. https://www.legislation.gov.uk/uksi/2002/2677/2020-12-31/data.pdf (Accessed: February 9, 2026).
COSHH health surveillance – COSHH (no date). https://www.hse.gov.uk/coshh/basics/surveillance.htm#:~:text=Health%20surveillance%20is%20different%20from%20general%20health,it%20likely%20that%20the%20disease%20will%20appear.
Health and Safety Executive (HSE) (2024) Health surveillance for those exposed to respirable crystalline silica (RCS), Health Surveillance for Those Exposed to Respirable Crystalline Silica (RCS). supplementary guidance, pp. 1–3. https://www.hse.gov.uk/pubns/priced/healthsurveillance.pdf.
Graham, B.L. et al. (2019) ‘Standardization of Spirometry 2019 Update. An official American Thoracic Society and European Respiratory Society Technical Statement,’ American Journal of Respiratory and Critical Care Medicine, 200(8), pp. e70–e88. https://doi.org/10.1164/rccm.201908-1590st.
Çolak, Y. et al. (2019) ‘Prognostic significance of chronic respiratory symptoms in individuals with normal spirometry,’ European Respiratory Journal, 54(3), p. 1900734. https://doi.org/10.1183/13993003.00734-2019.
Stubbe, B. et al. (2025) ‘Preserved Ratio Impaired Spirometry (PRISm) from an Epidemiological Perspective,’ Journal of Clinical Medicine, 14(21), p. 7831. https://doi.org/10.3390/jcm14217831.
Townsend, M.C. (2020) ‘Spirometry in Occupational Health—2020,’ Journal of Occupational and Environmental Medicine, 62(5), pp. e208–e230. https://doi.org/10.1097/jom.0000000000001851.
Stanojevic, S. et al. (2021) ‘ERS/ATS technical standard on interpretive strategies for routine lung function tests,’ European Respiratory Journal, 60(1), p. 2101499. https://doi.org/10.1183/13993003.01499-2021.
