How Aging Affects Your Lung Capacity and Ways to Protect Your Lungs

Lung capacity — the amount of air your lungs can hold and move with each breath — changes over our lifetime. Many people first notice the difference in middle age, when physical activities that once felt easy gradually require more effort. According to pulmonologist Michael Mohning, MD, these changes are part of the natural aging process. However, there are also ways to slow the decline and protect lung health.

How Lung Capacity Changes

Doctors can measure your lung capacity through pulmonary function tests, such as spirometry, which assess how much air you can move in and out of your lungs. This is a key marker of your respiratory health, reflecting both lung structure and muscle strength.

“Typically, lung capacity increases from birth to about age 20 or 25,” according to Dr. Mohning. “And then it peaks and stabilizes for the next 5 to 10 years. Around age 35, it starts to decline.” As a result, age is one of the strongest predictors of lung function. The decline is gradual, but measurable, with a loss of about 1% of total lung capacity every year after the age of 35. 

This is due to the way our lungs age. “Just like our skin changes as we age, our lungs change,” said Dr. Mohning. “The elasticity in the lung starts to decrease. And you get a gradual collapse of the small airways.” The muscles involved in respiration, such as those in the diaphragm, also begin to atrophy as we get older — just like the rest of our body’s muscles. 

Other structural changes create additional challenges. “The bones don't expand quite as well as we age. The rib cage doesn't expand as much,” said Dr. Mohning. Meanwhile, at the cellular level, aging causes “senescent cells,” which, true to their name, will “forget” what they’re supposed to do. “They’ll just sit there and release proteins or other substances that may contribute to disease processes,” said Dr. Mohning. 

Factors That Impact Lung Capacity

Not everyone’s lungs age at the same pace. Different exposures across a lifetime play a major role. “Things like tobacco smoke, pollution and bacterial infections. All those things over time tend to add up,” said Dr. Mohning.

Smoking is the single biggest factor. “We know that people who smoke tend to have a more rapid decline in their lung function than non-smokers,” Dr. Mohning said. Additionally, living in highly polluted areas, working in certain occupations with dust or chemical exposure, and experiencing repeated lung infections can also accelerate decline.

Genetics and baseline fitness matter as well. “People who grew up very active, people who were athletes at a young age, start out with a higher lung capacity,” said Dr. Mohning. “There are also a lot of genetics that play into the size of your lungs. It's a spectrum. Some people have really big lungs and some people have small lungs to begin with. And if you're starting from a higher lung capacity, then by the time you hit 80, you're going to be much better off than somebody who started at a low level.” This benefit reinforces the importance of encouraging young people to be active early in life. 

What Can You Do to Protect Your Lungs?

Unfortunately, once lung capacity declines, it cannot be restored.   However, there are proven ways to slow the loss and keep your lungs functioning at their best.

“Obviously avoidance of exposures is first and foremost. If you're a smoker, you absolutely have to quit,” said Dr. Mohning. “Protecting against infections is also key. Taking appropriate precautions, getting your vaccination so that you don't get infections, your flu vaccine, your COVID and RSV vaccines. All of those will help stop infections from damaging your lungs and decreasing the rate of your lung capacity decline.” 

Exercise is another essential tool, as even though your lung capacity can’t be restored, you can strengthen your respiratory muscles so that they’re more efficient. “You can exercise your diaphragm with cardio or aerobic activity. Activities that make you huff and puff are good for your lungs,” said Dr. Mohning. 

Breathing techniques can also help, especially if you have a condition that’s inhibiting your lungs, such as chronic obstructive pulmonary disease. Additionally, tools such as inspiratory muscle trainers can help strengthen your diaphragm.  

Finally, Dr. Mohning encourages patients to stay active not only for fitness, but also for awareness. “If you're really active, you're more likely to recognize a decline in your lung function, whereas if somebody is sedentary and they don't do a lot, it's going to take more of a decline in their lung function for them to notice.”

For those who want to track their lung health, a baseline test could be valuable. “In an ideal world, it would be great if everybody knew their lung function at age 25,” Dr. Mohning said. “If you have the means or the interest, it's a good number to know.”

Published September 2025