Why your lungs matter
Chronic obstructive pulmonary disease (COPD), a long-term narrowing of the airways that makes it hard to breathe out, caused 3.4 million deaths in 2023, about 6% of all deaths worldwide. In the US, chronic lower respiratory diseases, mostly COPD, were the fifth leading cause of death in 2024. Nearly 16 million US adults have COPD, and many more do not know it.
- 3.4M COPD deaths worldwide in 2023 (WHO)
- 145,643 US deaths from chronic lower respiratory disease in 2024 (CDC)
- 72% of US adults with airflow obstruction were undiagnosed (Martinez 2015)
Lung function predicts lifespan
The key number from a breathing test is FEV1, the volume of air you can blow out in one second. It tracks survival in a way few tests do. In the Framingham study, lung capacity showed a striking relation to mortality in both sexes that smoking did not explain. In the Buffalo Health Study, which followed 1,195 randomly selected adults for 29 years, people in the lowest fifth of FEV1 had 2.24 times the death rate of the highest fifth (men) and 1.81 times (women), after adjusting for smoking, blood pressure, and weight, and about twice the rate of death from coronary heart disease. Strong
Low lung function is a marker of whole-body risk, not just lung risk. In a 2017 Lancet Respiratory Medicine analysis of the Framingham Offspring and CARDIA cohorts, the 10–13% of adults with an FEV1 below 80% of predicted at age 25 to 40 developed heart, lung, and metabolic disease about a decade earlier and had 2.3 times the risk of death, independent of smoking.
A lifelong trajectory
Lung function rises through childhood, peaks at around 20 to 25, and then declines slowly. COPD can come from a fast decline, but it can also come from a low peak. In three cohorts followed for 22 years, about half of people who developed COPD had a normal FEV1 before 40 and then lost about 53 mL a year; the other half started low and lost a normal 27 mL a year. In a Tasmanian cohort tested from age 7 to 53, three below-average trajectories accounted for 75% of COPD, and they were linked to childhood asthma, pneumonia, and maternal smoking.
The practical point: your starting position is partly set before adulthood, so the only lever you control now is the rate of decline, and the only way to see either is to measure.
COPD in plain language
COPD covers emphysema (damaged air sacs) and chronic bronchitis (inflamed, mucus-filled airways). It is diagnosed when, after a dose of an inhaled bronchodilator, the ratio of FEV1 to FVC (the total air you can blow out) stays below 0.7. The damage cannot be reversed, but its progression can be slowed.
What causes it
Smoking causes over 70% of COPD in high-income countries, but it is not the whole story. In the international BOLD study, never-smokers made up 23.3% of people with moderate or worse COPD.
- Tobacco and other smoke Cigarettes and secondhand smoke cause most cases. Quitting is the single most effective treatment; see Tobacco and nicotine and Cannabis.
- Work dust and fumes Workplace exposures cause an estimated 14% of COPD and 16% of adult asthma.
- Air pollution and household smoke Long-term ozone and fine particle exposure was linked to faster emphysema progression in 7,071 US adults. Wood and other biomass smoke is a major cause worldwide.
- Early life and asthma Prematurity, low birth weight, childhood infections, and childhood asthma can limit peak lung growth.
- Genes Alpha-1 antitrypsin deficiency is the best-known inherited cause; see below.
Symptoms and diagnosis
The usual symptoms are breathlessness with exertion, a daily cough, phlegm, wheezing, and chest infections that keep coming back. They creep in so slowly that people adjust by doing less and blame age or fitness. Undiagnosed obstruction is not harmless: in national surveys, people with undiagnosed obstruction had a 23% higher death rate over 14.5 years than people with normal lungs.
The diagnosis needs spirometry; a chest X-ray or CT scan can suggest emphysema but cannot confirm COPD. Your doctor will also ask about early life events such as prematurity and childhood infections, workplace exposures, and family history.
The GOLD 2026 report
The Global Initiative for Chronic Obstructive Lung Disease (GOLD) publishes the main international COPD strategy each November. The 2026 report, released in November 2025 and current as of October 2026, made several changes:
- One flare-up now counts. Because even one moderate exacerbation (a flare needing steroids or antibiotics) predicts more, a single moderate flare should prompt a step up in treatment, aiming for none.
- Disease activity. New definitions of stable and controlled COPD: no flare-ups, no worsening symptoms, and no accelerated loss of lung function.
- Finding the undiagnosed. An updated case-finding section and algorithm for testing people with symptoms or risk factors.
- Vaccines and biologics. Updated RSV and flu vaccine advice, and a new summary of evidence for biologic drugs in people with frequent flares.
Quitting smoking still changes the course of the disease more than any drug. In the Lung Health Study of 5,887 middle-aged smokers with mild, symptom-free airway obstruction, a 10-week quit program lowered deaths over 14.5 years (8.83 versus 10.38 per 1,000 person-years) even though only 21.7% quit. Strong
Spirometry: who should get it
Spirometry is a short office test. You blow out as hard and as long as you can into a tube, usually before and after a puff of a bronchodilator. It measures FEV1, FVC, and their ratio, and modern standards compare your numbers with the lower limit of normal for healthy people of your age, sex, and height. Since 2023, the American Thoracic Society has recommended race-neutral reference equations in place of race-specific ones.
Who should be tested
| Who | Optimal plan | Basis |
|---|---|---|
| Breathlessness, chronic cough or phlegm, wheeze, frequent chest infections | Spirometry now, with a bronchodilator | Guideline (GOLD 2026) |
| Ever smoked or vaped, or years of dust, fumes, or wood smoke | Baseline spirometry now or by 40; repeat every 3 to 5 years while exposure continues | GOLD case-finding; interval is expert |
| Childhood asthma, prematurity, or a parent with COPD | Baseline in your 30s or 40s | Expert |
| Adult asthma | Spirometry at diagnosis and when control changes | Guideline |
| Everyone else, 40 or older | Optional one-time baseline | Expert; Weak |
Guideline minimum: the USPSTF recommends against screening adults without symptoms (grade D, reaffirmed in 2022), because finding and treating COPD in people who feel fine has not been shown to improve outcomes. GOLD likewise does not recommend screening spirometry for people with no symptoms and no significant exposures, but it does recommend testing anyone with symptoms or risk factors. Few people get that test: in surveys of 30,874 adults over 40 in 27 countries, only 26.4% had ever had a lung function test, and 81.4% of COPD was undiagnosed.
The case for a baseline
The argument for testing people with exposures is that it finds disease early and changes behavior. In the Step2quit trial of 561 smokers over 35, telling people their "lung age" after spirometry doubled verified quit rates at 12 months (13.6% versus 6.4%), and 16% of participants received a new diagnosis of obstructive lung disease. Moderate
For people with no risk factors, a baseline is a personal choice. It is cheap and harmless, and it gives you a reference number so a later decline is obvious. But no trial shows it improves outcomes, and a borderline result can lead to labels and inhalers you do not need.
How to get an accurate test
- Avoid smoking or vaping and vigorous exercise for 1 hour before, avoid alcohol or other intoxicants for 8 hours, and wear clothing that does not restrict your chest.
- Ask whether you should skip your usual inhalers beforehand; it depends on the question being asked.
- Ask for a test before and after a bronchodilator, which is required to diagnose COPD.
- The test depends on effort. A good technician will coach you and repeat each blow until the results agree.
- Get a copy of the numbers (FEV1, FVC, ratio, and the percent predicted or z-scores) so future tests can be compared.
PRISm and pre-COPD
Some people have a normal FEV1-to-FVC ratio but a low FEV1, below 80% of predicted. This pattern is called preserved ratio impaired spirometry (PRISm). GOLD also uses pre-COPD for people with symptoms or other lung abnormalities but no obstruction. Both are at risk of developing COPD, though not all do.
PRISm is common and matters. In pooled data from nine US cohorts, 8.5% of 53,701 adults had PRISm, which was linked to obesity and smoking. Their death rate was 29.6 per 1,000 person-years versus 18.0 with normal spirometry, with higher rates of heart and lung deaths. In the Rotterdam Study of older adults, 49.4% of people with PRISm who were retested 4.5 years later had developed COPD, and 15.7% had returned to normal.
There is no proven drug treatment for PRISm. Treat it as a warning: stop smoking, work on weight and fitness, check your heart risk (see Heart and blood vessels), and repeat spirometry in a year or two. That interval is expert practice. Moderate
Alpha-1 antitrypsin deficiency
Alpha-1 antitrypsin is a liver protein that protects the lungs from enzymes released by white blood cells. People who inherit two faulty copies of the gene have low levels and can develop emphysema young, especially if they smoke, and some develop liver disease. It affects about 1 in 1,500 to 3,500 people of European ancestry, roughly 100,000 Americans, and most cases are never diagnosed.
Who should be tested once:
- Everyone with COPD. GOLD recommends that all patients with COPD be tested. Moderate
- Asthma that never fully clears, unexplained bronchiectasis (permanently widened airways), or unexplained liver disease, per the Alpha-1 Foundation's 2016 guideline.
- Parents, siblings, and children of anyone with the deficiency; the same guideline calls family testing the most efficient way to find cases.
The test is a blood level of alpha-1 antitrypsin plus a genotype, and it only needs doing once. A positive result changes a lot: absolute avoidance of smoking and dust, liver monitoring, testing relatives, and, for people with emphysema, the option of regular infusions of the missing protein (augmentation therapy).
Asthma in adults
About 23 million US adults, or 8.9%, had asthma in 2023, and 3,458 adults died of it. Asthma narrows the airways in episodes, usually reversibly, and it can start at any age. New asthma in adulthood should prompt questions about work, since workplace exposures cause an estimated 16% of adult asthma.
Control is prevention. Poorly controlled asthma means flare-ups, and childhood asthma is one of the strongest predictors of a low lung function trajectory and later COPD.
What good asthma care looks like:
- A diagnosis confirmed by spirometry or other lung testing, not symptoms alone.
- A controller strategy that includes an inhaled steroid, reviewed at least once a year and after any flare. GINA assesses control by how often you have symptoms, wake at night, limit activity, or reach for your reliever.
- A written action plan, inhaler technique checked at each visit, and a flu vaccine every year.
- Alpha-1 testing if obstruction persists even when treated.
The current GINA strategy is the 2026 report.
Lung nodules found by accident
A lung nodule is a small spot on a chest CT. They are very common and usually benign: in one large health system, nodules turned up on 31% of chest CTs, which extrapolates to 1.57 million Americans a year, yet the rate of new lung cancer diagnoses did not rise as more nodules were found. Scans done for other reasons often include part of the lungs: in one registry, nodules were reported on 28% of heart CT scans done for chest pain.
The Fleischner Society's 2017 guidelines set how much follow-up an incidental solid nodule needs in adults 35 and older. They do not apply to lung cancer screening scans, people with cancer, or people with weakened immunity.
| Single solid nodule | Low risk | Higher risk (for example, a smoking history) |
|---|---|---|
| Under 6 mm | No routine follow-up | Optional CT at 12 months |
| 6–8 mm | CT at 6 to 12 months, then consider one at 18 to 24 months | CT at 6 to 12 months and at 18 to 24 months |
| Over 8 mm | Consider CT at 3 months, PET-CT, or a biopsy | Same |
More scans than this add radiation and anxiety without benefit. Ask whether the radiologist used these guidelines, and whether older scans show the spot was already there. Lung cancer screening uses a separate system. The optimal plan, following the American Cancer Society's 2023 guideline, is a yearly low-dose CT from 50 to 80 for anyone with 20 or more pack-years of smoking, however long ago they quit; never-smokers should not have screening CTs. Details are in Lung cancer, and general advice on incidental findings is in If a scan finds something.
Exposures at work and home
Workplace dust and fumes
An American Thoracic Society and European Respiratory Society review estimated that work exposures cause 14% of COPD, 16% of adult asthma, and 26% of idiopathic pulmonary fibrosis, a scarring disease.
Silicosis, scarring from silica dust, has returned among workers who cut engineered stone ("quartz") countertops. From 2019 to mid-2026, California identified 592 cases among these workers; 65 needed lung transplants and 31 died.
If you work around dust, fumes, or chemicals, use the wet-cutting, ventilation, and fitted respirators your industry calls for, tell your doctor your job history, and get baseline spirometry.
Air, smoke, and radon
Outdoor air pollution, wildfire smoke, gas stoves, and radon all affect the lungs, and they are covered in Avoiding harm. The optimal plan from that chapter: run a HEPA purifier in your bedroom every night (Purifiers and ventilation), vent or replace a gas stove (Indoor air and gas stoves), and test your home for radon every two years, fixing it at 2.7 pCi/L or higher. People with lung disease are a sensitive group on poor air days, so they should check the air quality index daily during smoke season; see Outdoor air and wildfire smoke.
Vaping and lung injury
In 2019, an outbreak of severe e-cigarette or vaping product use-associated lung injury (EVALI) led to 2,807 hospitalizations or deaths, including 68 deaths, by February 2020. Most cases were linked to THC vaping products from informal sources, and vitamin E acetate, an additive in some of them, was strongly linked to the outbreak. Do not vape THC products bought outside regulated channels. Nicotine e-cigarettes as a way to quit smoking, and their unknown long-term effects, are covered in Vaping.
Breathing, fitness, and sleep
Fitness protects lung function
Breathlessness on exertion is often the first sign of lung disease. Your VO2 max, your maximum oxygen uptake, is one of the strongest predictors of survival: in 122,007 patients who had treadmill tests, the least fit quarter had about five times the death rate of the fittest few percent. The optimal plan is a lab VO2 max test every year (How often to test) and 300 to 600 moderate-equivalent minutes of exercise a week; how to build it is in VO2 max training.
Activity may also protect the lungs. In a Copenhagen cohort, smokers who were moderately or highly active lost lung function more slowly and had 23% lower odds of developing COPD than inactive smokers. This was observational, and it is no substitute for quitting. Moderate
If your breathlessness seems out of proportion to your fitness, or your exercise capacity drops for no clear reason, get spirometry and a heart evaluation rather than assuming you are out of shape.
Inspiratory muscle training
Inspiratory muscle training (IMT) means breathing in against resistance through a small handheld device, usually for a few minutes a day. The evidence depends on the goal. Mixed
| Goal | What trials found | Evidence |
|---|---|---|
| Endurance performance in healthy people | A review of 46 studies found improvement, larger in less fit people | Moderate |
| Blood pressure | 30 breaths a day for 6 weeks lowered systolic pressure from 135 to 126 mm Hg versus sham in 36 adults aged 50 to 79 | Weak |
| COPD, added to rehab | Stronger breathing muscles but no gain in walking distance in 219 patients | Mixed |
| Before major surgery | Pneumonia after surgery roughly halved in 12 trials, with risk of bias | Moderate |
IMT is cheap and safe, so it is a reasonable add-on before planned chest or abdominal surgery, or as a blood pressure experiment alongside proven measures. It does not replace aerobic training. Slow-breathing practices for stress are in Mind and connection.
Sleep-disordered breathing
Obstructive sleep apnea is repeated collapse of the throat during sleep. It often coexists with COPD, and GOLD notes that in people with both, CPAP treatment lowers the risk of death. The optimal plan is a home sleep test for anyone who snores regularly or has high blood pressure, atrial fibrillation, or heart disease; see Who should get tested.
Flare-ups, vaccines, and rehab
Vaccines
COPD flare-ups are mainly triggered by respiratory viruses, along with bacteria, air pollution, heat, cold, and wildfire smoke. GOLD 2026 advises that people with COPD receive flu, pneumococcal, RSV, and COVID-19 vaccines, a Tdap booster if they missed it as adolescents, and the shingles vaccine. Chronic lung disease makes you eligible for several of these earlier than other adults; see RSV, pneumococcal, and flu vaccines.
Pulmonary rehabilitation
Pulmonary rehabilitation is a supervised program, usually 8 to 12 weeks, of exercise training, breathing techniques, and education. A Cochrane review of 65 trials with 3,822 people with COPD found moderately large, clinically significant improvements in breathlessness, fatigue, and quality of life, and the authors concluded that more trials against usual care are not needed. Strong After a hospital stay for a flare, rehab reduced readmissions in moderate-quality evidence.
It is badly underused. Among 197,376 Medicare patients hospitalized for COPD in 2014, only 1.5% started rehab within 90 days. Those who did had a one-year death rate of 7.3% versus 19.6%, a 37% lower risk after adjustment, though this was observational and healthier patients may be more likely to attend. If you have COPD and get breathless with daily activities, or have just been hospitalized, ask for a referral.