In brief
A pulmonary function test (PFT) measures how much air can be blown out of the lungs with a forced breath and how fast. In the workplace, its real value comes not from a single result but from comparisons with the baseline value taken at pre-employment. The legislation does not set a fixed PFT frequency for everyone; the workplace physician decides according to exposure. For asbestos work, however, the regulation lists the PFT as part of health surveillance.
What is a pulmonary function test (PFT), and why is it done in the workplace?
The pulmonary function test, in its most common form spirometry, is carried out by having the person take a deep breath and then blow the air out as quickly and forcefully as possible. The device measures the volume of air exhaled and the flow rate. The test is short and painless, and when done correctly it can show narrowing of the airways or a reduction in lung volume before symptoms appear.
The answer to the question "what is a PFT" in the workplace is slightly different from its clinical use. The aim is not to make a one-off diagnosis but to monitor over time the lung function of workers exposed to dust, fumes, gases or vapours. This monitoring serves three purposes: catching a work-related disease early, seeing whether the measures taken are adequate, and providing evidence for diagnosis when occupational disease is suspected.
The place of the PFT in the legislation is as follows:
- There is no fixed PFT frequency for all workers. The workplace physician decides which workers are tested and at what interval, according to the risk assessment and exposure. For the general rules, see our article on periodic examinations and tests.
- Annex I of the Regulation on Health and Safety Measures for Work with Asbestos lists the pulmonary function test together with chest radiography among the minimum elements of the health examination.
- The list of occupational diseases requires adequate pulmonary function tests in the diagnosis of diseases such as occupational bronchial asthma, byssinosis and asbestosis. For the list, see our article on the list of occupational diseases.
Who needs a PFT?
The answer to "who needs a PFT" comes from the exposure list. The main groups, with examples from the chemicals and plastics sector, are:
| Exposure | Example jobs | Why is it monitored? |
|---|---|---|
| Isocyanates | Polyurethane foam, hardeners for two-component paints and varnishes | Occupational asthma; one of the agents named in the list |
| Formaldehyde and phthalic anhydride | Resin, adhesive and plasticiser production | Occupational asthma and airway irritation |
| Plastic, filler and pigment dusts | Granules, masterbatch, powder coating preparation | Airway irritation, chronic effects |
| Quartz-containing dust | Fillers, ceramics, foundry, stone processing | Pneumoconiosis; monitored together with chest X-ray |
| Welding and metal fumes | Welding, cutting, metal plating | Airway and lung effects |
| Asbestos | Removal, maintenance and demolition work | Asbestosis; the regulation explicitly requires the PFT |
In addition, the physician may request a PFT to assess whether workers who will use respiratory protection continuously can use it safely. For the general framework of chemical exposure, see our article on the chemical agents regulation, and for the isocyanate risk on paint lines, our article on spray booth and painter risks.
The pre-employment PFT: why is the baseline important?
Suppose a worker's FEV1 is measured at 95 per cent of the predicted value. This result looks normal. But if the same worker's value at pre-employment was 115 per cent, a significant loss has occurred over a few years. A result that is "normal" compared with the predicted value can hide a meaningful decline compared with the person's own history.
This is why the PFT is carried out at the pre-employment examination, before exposure begins, and becomes the reference point for all subsequent tests. For the pre-employment PFT to be useful:
- The test is carried out together with the pre-employment examination and before the worker moves to the risky department,
- Raw values (in litres) are recorded, not just the interpretation "normal",
- Height, age and sex are entered correctly; the same reference equation is used in subsequent tests,
- Smoking and previous lung diseases are recorded.
For where to obtain the pre-employment report, see our article on the pre-employment medical report.
FEV1, FVC and the ratio: what do the values tell you?
| Value | What does it measure? | What may a low value indicate? |
|---|---|---|
| FVC (forced vital capacity) | Total volume of air that can be forcefully exhaled after a deep breath | Reduced lung volume or insufficient test effort |
| FEV1 | Volume of air exhaled in the first second of this forced breath | Narrowing of the airways or loss of volume |
| FEV1/FVC ratio | Ratio of air exhaled in the first second to the total volume | If the ratio is low, airway obstruction (obstructive impairment) |
In reports, the FEV1/FVC ratio, written as FEV1/FVC or as a percentage, allows the two measurements to be read together. The values are compared with the predicted value calculated according to the person's age, height and sex. Current guidelines recommend using the lower limit of the reference group (the lower limit of normal) rather than a fixed percentage. The main outlines of interpretation are:
- Low FEV1/FVC ratio: Suggests an obstructive impairment; seen in asthma and chronic obstructive diseases.
- Normal ratio, low FVC: Suspected reduction in lung volume, that is, a restrictive impairment; further tests such as lung volume measurement are needed for a definitive assessment.
- Both at once: There may be a mixed impairment; the physician requests further assessment.
The interpretation is made by the workplace physician; the table above is to help workers and employers understand the report.
Test quality: how to avoid false results
The biggest problem with the PFT is a poorly performed test. Insufficient effort, a breath stopped too early or an attempt spoiled by coughing gives a low result while the lungs are healthy; it also makes year-to-year comparison meaningless. For a good-quality test:
- The worker does not smoke or do strenuous exercise for at least one hour before the test, and does not wear clothing that is tight around the chest and abdomen.
- At least three acceptable attempts are made; the difference between the FEV1 and FVC values of the two best attempts should be small (within 150 mL in the international standard).
- Device calibration and the training of the person performing the test are recorded.
- Tests to be compared are, if possible, carried out with the same type of device at a similar time of day.
- The attempt curves are also attached to the report; the physician can see the quality from the curves.
We plan measurements and tests with authorised healthcare providers; the assessment of results is the responsibility of the workplace physician.
How is decline tracked over the years?
FEV1 decreases naturally with age. The question to ask in monitoring is: is this person's loss greater than age would explain? One approach used in international occupational health guidelines (such as publications of the American Thoracic Society and the American College of Occupational and Environmental Medicine) is to treat a decline of about 15 per cent from the pre-employment value, in addition to the expected age-related loss, as the threshold for further assessment. There is no numerical threshold in Turkish legislation; the interpretation is made by the physician.
Example calculation. Suppose a worker's FEV1 at pre-employment is 3.80 L. According to the reference equation, suppose this person's expected loss due to age after five years is 0.15 L (example value).
- 15 per cent margin: 3.80 × 0.15 = 0.57 L
- Further assessment limit: 3.80 − 0.15 − 0.57 = 3.08 L
- If the fifth-year measurement is 3.30 L, it is above the limit; but the trend is monitored.
- If the measurement is 3.00 L, it is below the limit; the test is repeated and, if confirmed, the worker is referred for further assessment.
A single low result can also be explained by test quality or a temporary infection. A suspicious result is therefore repeated within a few weeks, and the decision is based not on a single measurement but on the trend.
What happens if the result is poor?
- Physician assessment. The workplace physician repeats the test and assesses symptoms and exposure history; if necessary, refers the worker to a chest diseases specialist.
- Review of exposure. Local exhaust ventilation, closed systems and the use of respiratory protection are checked; if necessary, workplace exposure measurement is carried out and the risk assessment is updated.
- Fitness for work. The physician decides whether the worker can continue working with the same exposure and, if necessary, on a change of job.
- Suspected occupational disease. If the findings suggest a work-related disease, the process is started; for the steps, see our article on occupational disease diagnosis and notification.
Workers' health information is confidential; only the fitness-for-work result and the measures to be taken are passed on to the employer. For the rules on chest X-rays in dusty work, see our article on the Regulation on Dust Control, and for PFT and radiography follow-up in asbestos work, our article on asbestos removal work.
At chemicals and plastics businesses in Bursa and the surrounding provinces, we plan tests including the PFT as part of our health surveillance service; for other risks in the sector, see our chemicals and plastics page.
Frequently Asked Questions
Does the PFT have to be done every year?
There is no fixed PFT frequency for all workers in the legislation. The workplace physician determines who is tested and at what interval according to exposure, the risk assessment and previous results. Since periodic examinations are carried out every year in very hazardous work, any PFT deemed necessary can be planned together with this examination.
Why is the pre-employment PFT so important?
All subsequent tests are compared with this value. A result that looks normal compared with the predicted value can hide a significant decline compared with the person's own starting value. Without a baseline, this decline goes unnoticed.
What is the difference between FEV1 and FVC?
FVC is the total volume of air that can be forcefully exhaled after a deep breath. FEV1 is the part of this volume exhaled in the first second. If the ratio between the two is low, narrowing of the airways is suspected.
Does smoking affect the PFT result?
Yes. Smoking can cause loss of lung function over time, and smoking shortly before the test can affect the result. This is why smoking is recorded and the worker is asked not to smoke for at least one hour before the test.
An exposure-based test plan, pre-employment and periodic examinations, confidential health files and an examination schedule tracked per person.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.