Spirometry: What It Is, Why It Matters, and What Your Results Mean

When your doctor suspects you have trouble breathing, they often turn to spirometry, a basic lung function test that measures how much air you can breathe in and out, and how fast you can do it. Also known as a pulmonary function test, it’s one of the most common, non-invasive ways to check if your lungs are working right. You don’t need needles, radiation, or fasting. You just breathe into a tube connected to a machine. But don’t let its simplicity fool you—this test can spot problems long before you feel symptoms.

Spirometry doesn’t just diagnose asthma or COPD. It helps track how those conditions change over time, whether your inhalers are working, or if you’re losing lung function due to smoking, pollution, or aging. The two main numbers doctors look at are FEV1, the amount of air you can forcefully exhale in one second, and FVC, the total amount of air you can exhale after taking a deep breath. If your FEV1/FVC ratio is low, it often means your airways are narrowed—classic in asthma or COPD. But it’s not just about those two numbers. The shape of the curve, how quickly you start exhaling, and how your results compare to people your age, height, and gender all matter.

It’s not just for people with known lung disease. If you’ve been coughing for months, get winded climbing stairs, or have a long smoking history, spirometry can give you answers. And if you’re on medications that might affect your lungs—like some chemotherapy drugs or long-term steroids—it’s often part of routine monitoring. The test is quick, safe, and usually covered by insurance. You might feel a little dizzy or tired afterward, but serious side effects are rare.

What you’ll find in the posts below isn’t just about how spirometry works. It’s about how it connects to real-life health decisions. You’ll see how it’s used to guide treatment for asthma and COPD, why some people get misdiagnosed because the test wasn’t done right, and how other conditions like heart failure or obesity can mimic lung disease on the results. There’s also advice on how to prepare so you get accurate numbers, what to ask your doctor when you get the report, and how to use those numbers to make smarter choices about your breathing health.