Getting your lungs checked typically starts with a visit to your primary care doctor, who can perform basic breathing tests in the office and order imaging or refer you to a lung specialist if needed. The specific tests you’ll get depend on your symptoms, risk factors, and what your doctor is looking for, but most lung evaluations begin with a simple, painless breathing test called spirometry.
Signs You Should Get Your Lungs Checked
Not every cough warrants a full lung workup, but certain symptoms signal that something deeper may be going on. Doctors typically order lung function testing when you report chest tightness or pressure, a persistent cough (especially one producing mucus), difficulty taking a deep breath, shortness of breath during normal activities, or wheezing. If any of these have lingered for several weeks or are getting worse, that’s a good reason to bring it up with your doctor.
You don’t need symptoms to get screened, though. If you smoke or used to smoke, work around dust or chemicals, or have a family history of lung disease, proactive testing can catch problems early, before they cause noticeable symptoms.
Spirometry: The First Test Most People Get
Spirometry is the most common lung function test and the one your primary care doctor is most likely to start with. You breathe into a mouthpiece connected to a machine, inhale as deeply as you can, then blow out as hard and fast as possible. The whole effort takes a few seconds, and you’ll usually repeat it two or three times so the technician can get consistent readings.
The test measures two key numbers: how much air your lungs can hold (forced vital capacity) and how much air you can push out in the first second of a hard exhale (FEV1). In healthy lungs, that first-second blast accounts for about 75% to 85% of your total exhale. When the ratio drops below normal, it suggests an obstructive problem like asthma or COPD, where your airways are narrowed. When both numbers are low but the ratio stays normal, it points toward a restrictive problem, where your lungs can’t fully expand.
Doctors used to use a fixed cutoff of 0.70 for that ratio, but current guidelines from the American Thoracic Society now adjust for your age, sex, and height. This matters because the ratio naturally declines as you get older, and using a one-size-fits-all number can lead to misdiagnosis in older adults.
What Imaging Can Reveal
A chest X-ray is the quickest way to get a picture of your lungs. It can show fluid buildup, infections, large masses, and structural problems. It’s fast, widely available, and inexpensive, but it has limits. Small nodules and early-stage cancers often don’t show up on a standard X-ray.
Low-dose CT scans (LDCT) are far more sensitive. Studies like the National Lung Screening Trial and the Early Lung Cancer Action Program have consistently shown that LDCT detects small lung nodules and early-stage cancers that chest X-rays miss entirely. The tradeoff is a higher rate of false positives, meaning the scan may flag something that turns out to be harmless, sometimes leading to follow-up scans or biopsies. Still, for people at high risk of lung cancer, the benefit of early detection outweighs that downside.
Who Qualifies for Annual Lung Cancer Screening
The U.S. Preventive Services Task Force recommends annual LDCT screening for adults aged 50 to 80 who have a 20 pack-year smoking history and either currently smoke or quit within the past 15 years. A pack-year means smoking one pack per day for one year, so someone who smoked two packs a day for 10 years has the same 20 pack-year history as someone who smoked one pack a day for 20 years.
Screening stops once you’ve been smoke-free for 15 years or if a health condition limits your life expectancy or ability to undergo treatment. Most insurance plans, including Medicare, cover this screening at no cost when you meet the criteria. Your primary care doctor can determine your eligibility and place the order.
Specialized Tests for Specific Conditions
If spirometry suggests a problem or your doctor needs more detail, several additional tests can narrow the diagnosis.
Bronchoprovocation (methacholine challenge): This test is used when asthma is suspected but spirometry looks normal. You inhale increasing concentrations of methacholine, a substance that temporarily narrows the airways, with spirometry measured after each dose. The test is positive if your FEV1 drops by 20% or more, confirming that your airways are hyperreactive. The whole process takes about 30 to 60 minutes, and any airway tightening is reversed with an inhaler immediately afterward.
Diffusion capacity testing: This measures how efficiently oxygen passes from your lungs into your bloodstream. You breathe in a small, harmless amount of carbon monoxide, hold your breath briefly, then exhale. The machine calculates how much gas was absorbed. Low results can indicate damage to the tiny air sacs in your lungs, which is common in emphysema and pulmonary fibrosis.
Six-minute walk test: Exactly what it sounds like. You walk at your own pace for six minutes while a technician tracks the distance you cover and monitors your oxygen levels. It’s a practical measure of exercise capacity used to assess the severity of conditions like COPD, pulmonary fibrosis, and pulmonary hypertension.
Monitoring at Home With a Peak Flow Meter
If you have asthma or another chronic lung condition, your doctor may give you a peak flow meter to use at home. It’s a small handheld device you blow into as hard as you can. It measures your peak expiratory flow rate, essentially how fast you can push air out. Research comparing peak flow meters to office spirometry found their overall accuracy was comparable (94% vs. 96%), making them a reliable way to track day-to-day changes between doctor visits. They’re especially useful for spotting early signs of a flare-up before symptoms become obvious.
A peak flow meter is not a replacement for a full diagnostic workup, but it gives you and your doctor useful trend data over time.
If You Work Around Dust or Chemicals
Workers exposed to silica dust, asbestos, coal dust, or other respiratory hazards have specific screening requirements under OSHA regulations. For silica-exposed workers, the standard calls for spirometry, a chest X-ray, a physical exam with focus on the respiratory system, and baseline tuberculosis testing, all at the initial evaluation. After that, spirometry, imaging, and a physical exam are repeated every three years. Your employer is required to provide this surveillance at no cost to you.
Doctors performing these evaluations may order more frequent testing, including annual TB screening, if you’ve been exposed to silica for 25 years or more or have already been diagnosed with silicosis.
How to Prepare for Lung Function Tests
Preparation matters because certain substances can temporarily change how your airways behave, skewing results. The National Heart, Lung, and Blood Institute provides specific guidelines:
- Don’t smoke on the day of your test. For exercise or diffusion testing, avoid smoking for at least 8 hours beforehand.
- Skip the large meal for at least 2 hours before the test. A full stomach can restrict your diaphragm.
- Avoid heavy exercise for at least 30 minutes before testing.
- No alcohol for at least 4 hours prior.
- Hold caffeine for 12 hours before exercise-related tests.
If you use inhalers or other breathing medications, you’ll likely need to stop them temporarily. Short-acting rescue inhalers like albuterol should be withheld for 6 hours. Long-acting inhalers need 24 to 36 hours. Ultra-long-acting medications require 36 hours or more. Your doctor’s office should give you specific instructions when scheduling the test, but don’t hesitate to call and ask if they don’t.
What the Process Looks Like Start to Finish
For most people, the path starts at your primary care doctor’s office. Many primary care practices have spirometry equipment on-site, so you can often get that first test done the same day you raise concerns. If the results are abnormal or inconclusive, your doctor will typically order imaging (a chest X-ray or CT scan) and may refer you to a pulmonologist for more detailed testing like full lung volume measurements, diffusion capacity, or bronchoprovocation.
The pulmonologist confirms the diagnosis, determines severity, and sets up a treatment plan. After that, ongoing management usually shifts back to your primary care doctor, with periodic specialist visits as needed. In practice, research suggests that many patients never see a pulmonologist even when guidelines recommend it, so if your symptoms persist or worsen after initial testing, asking for a referral is a reasonable step to take on your own.