Pulmonary Function Tests: What Are PEF, FVC, FEV, and FEV1/FVC?

A pulmonary function test is a group of breathing measurements that describe how well the lungs move air. The most common form is spirometry, in which a person inhales fully and blows out as hard and as long as possible into a mouthpiece while sensors record the volume and speed of that breath.

Spirometry does not photograph the lungs and does not identify a specific disease. It produces numbers describing airflow, and a qualified physician reads those numbers alongside symptoms, history and exposure.

Clinics On Cloud includes four pulmonary function parameters, PEF, FVC, FEV and FEV1/FVC, in its screening kiosks. Clinics On Cloud is India’s first CDSCO-licensed Health ATM and Health Kiosk manufacturer, based at Nighoje, Chakan MIDC, Pune, and builds spirometry into the same session as vitals, cardiac and point-of-care testing rather than as a separate appointment. People rarely book a lung test on their own, but they accept one that is already part of a checkup they are attending.

Kiosk software compares each value against predicted values for a person of the same age, sex and height, because a healthy 22-year-old and a healthy 62-year-old do not produce the same numbers. Those comparisons aid a clinician; they are not a verdict for the person tested.

No reference values, cut-offs or severity bands appear on this page on purpose. Interpretation depends on clinical context that a screening device cannot see.

Peak Expiratory Flow (PEF) is the fastest speed at which a person can force air out of the lungs during a single hard breath out. It reflects how freely air is moving through the larger airways at the moment of the test.

PEF is the quickest of the four to perform and the most effort-dependent. A half-hearted blow produces a low number that says nothing about the lungs, which is why kiosk software prompts for repeat attempts and why coaching the blow improves quality.

Forced Vital Capacity (FVC) is the total volume of air a person can blow out after taking the deepest possible breath in. It describes capacity rather than speed.

PEF asks how fast air leaves. FVC asks how much air there was to move at all. A reduced FVC prompts a clinician to consider conditions that limit how far the lungs or chest wall expand, described as a restrictive pattern. The manoeuvre needs a long, complete exhalation, and incomplete blows are the commonest reason a screening FVC is repeated.

Forced Expiratory Volume (FEV) is the volume of air blown out within a defined period of time, and in almost all screening that period is the first second, written FEV1. It combines the two ideas above: volume, measured against the clock.

FEV1 is the number clinicians look at most often, because airway narrowing shows up early in how much air can be moved quickly. It comes from the same single blow that produces FVC, so one good manoeuvre yields three of the four parameters here.

The FEV1/FVC ratio is the proportion of a person’s total forced breath out that leaves the lungs in the first second. It helps distinguish the pattern of a low reading rather than just its size.

Two different situations produce low numbers. Airflow that is narrowed slows the first second disproportionately. Lungs that hold less air reduce both figures together, so the ratio behaves differently. Read together, the three give a physician a direction to investigate.

Clinicians follow guidance from bodies such as the World Health Organization and, in India, ICMR-affiliated respiratory programmes when interpreting these patterns. Take any reading that concerns you to a qualified physician rather than comparing it against numbers found online.

• The user enters age, sex and height so the software can generate predicted comparisons.
• A fresh disposable mouthpiece is fitted, used by one person, then discarded.
• Voice and on-screen guidance, in multiple languages, instructs the user to breathe in fully, seal the lips and blow out as hard and as long as possible.
• Flow and volume sensors record the manoeuvre and calculate PEF, FVC, FEV1 and FEV1/FVC.
• The kiosk requests repeats until reproducible efforts are captured, because effort quality drives spirometry more than anything else.
• Results appear in a colour-coded report by print, SMS, email or WhatsApp, stored in a digital health record for longitudinal tracking.
• Where a result is flagged, the kiosk offers an integrated telemedicine consultation at the point of screening.

Clinics On Cloud states device accuracy of 90 to 95 percent depending on test and device, under correct usage, calibration and patient preparation. In spirometry, preparation carries unusual weight, since a poor blow is the commonest source of a misleading result.

Screening is most valuable where exposure or symptoms make reduced airflow plausible. These groups are commonly prioritised:

• Workers in dusty processes: stone crushing, quarrying, cement, foundry, ceramics, textiles and cotton handling.
• Workers exposed to fumes, vapours or welding smoke in fabrication, chemical and metal-finishing plants.
• Underground and open-cast mining workforces, construction crews and infrastructure teams.
• Traffic police, drivers, delivery riders and others working long hours in outdoor urban air.
• Adults with a smoking history, current or past.
• Anyone with a persistent cough, wheeze, chest tightness or breathlessness on ordinary exertion.
• School children in programmes where asthma is suspected but never assessed, and adults in corporate wellness programmes needing a baseline.

Frequency should be set by the occupational health physician or the treating doctor, not by the machine and not by the employer’s calendar alone.

Lung function is the occupational health parameter most often skipped, because a spirometer traditionally required a technician, a quiet room and an appointment. A screening kiosk removes all three constraints, which is why manufacturing, mining and infrastructure employers are the strongest Indian use case.

Indian occupational health obligations sit under the Factories Act, 1948 and its state rules for specified hazardous processes, with mining workforces additionally overseen by the Directorate General of Mines Safety. Confirm your statutory examination requirements with your factory medical officer, since they vary by process, state and workforce. Ambient air quality is monitored by the Central Pollution Control Board. This page states no pollution or prevalence figures, because none could be verified.

A Mobile Medical Unit rotates spirometry across plants. The portable Box Clinic runs it offline at remote sites with 3 to 4 days of battery backup. At a fixed plant gate, the Clinics On Cloud Health Kiosk is the standard build. Pair lung screening with ear health screening with audiometry and otoscope and far vision, near vision and colour blindness screening, the three fitness checks safety-critical roles most often require.

A pulmonary function screening result indicates one of three things, and none of them is a diagnosis.

A result within the expected range for your age, sex and height indicates that airflow looked unremarkable on the day of the test. It does not rule out lung disease, and it does not mean symptoms should be ignored.

A flagged result indicates that one or more measurements fell outside the predicted comparison and that a qualified physician should review it. That review may involve laboratory spirometry, testing before and after a bronchodilator, imaging or specialist referral. None of that is decided by a kiosk.

An invalid result indicates a technique problem rather than a lung problem. Incomplete exhalation, a leaking lip seal, coughing mid-blow and a hesitant start all corrupt spirometry. Repeat the test with coaching.

Do not compare your numbers with anyone else’s, and do not start, stop or change any medication on the basis of a screening report. Take the report to a qualified physician. Across the Clinics On Cloud network, 2 lakh+ abnormalities have been detected and routed for early intervention, and the value in that number is the follow-up, not the flag.

Kiosk spirometry is also bounded. Laboratory testing additionally measures lung volumes, gas transfer and response to medication under a trained technician, and Clinics On Cloud is not a diagnostic laboratory. The kiosk gives reach; the laboratory gives depth. For the wider parameter picture see clinical parameters and tests offered by a health kiosk, and for the heart screening usually read alongside breathlessness see cardiac tests explained: ECG, blood pressure and lipid profile.

To scope lung screening for a plant, mine site, school programme or corporate wellness calendar, call +91 8999 073 447, Monday to Saturday, 9:00 to 18:00 IST, or email sales@clinicsoncloud.com. Bring your headcount, site count and the other parameters you need in the same visit.