The test records how much air a person can force out and how quickly. The two numbers that matter most are FVC, the total forced volume, and FEV1, the volume in the first second. Their ratio is what distinguishes broad patterns of…
The test records how much air a person can force out and how quickly. The two numbers that matter most are FVC, the total forced volume, and FEV1, the volume in the first second. Their ratio is what distinguishes broad patterns of impairment. It is a screening and surveillance tool, not a diagnosis - a result outside expected range is a reason to see a physician, not a conclusion.
Spirometry is more dependent on coaching than almost any other workplace test. A poorly coached manoeuvre produces a low result that looks like impairment. Our technicians hold current NIOSH spirometry course certificates and we apply the ATS/ERS acceptability and repeatability criteria to every session - which sometimes means asking someone to blow again when they would rather not.
A single spirometry result tells you relatively little. The value is in the trend against that worker's own baseline over years. That is why we keep the equipment, technique and calibration consistent between visits - switching device or method between years introduces a step change that can look like a real decline.
Recent chest or abdominal surgery, recent heart attack, current pneumothorax, unstable angina, recent eye surgery, or an active respiratory infection. The forced manoeuvre raises intrathoracic pressure and in those situations that is a real hazard. Tell us and we will reschedule; there is no benefit in a result taken under those conditions anyway.
Primary regulations and standards referenced above. Where a standard is published commercially it is named in full rather than linked to a copy.