Dear Doctor: I prefer to breathe through my mouth at all times. This is due to fairly constant nasal congestion. Am I getting the same amount of oxygen as breathing through my nose?
Dear Reader: The answer is actually a bit more complex than a simple yes or no. Yes, the same amount of oxygen reaches your lungs whether you’re breathing in through your nose or your mouth. But something different happens to that oxygen when you breathe in through your nose, which doesn’t happen when you breathe through your mouth.
Breathing through the nose warms, filters and humidifies the air. Each of these is important to the health of the delicate tissues of the nose, lower airways and lungs.
Nose breathing has another beneficial effect on oxygen once it reaches the lungs, which doesn’t happen with mouth breathing. This is due to nitric oxide, a colorless and odorless gas. It’s produced throughout the body, including by the paranasal sinuses, which are the group of air-filled spaces in the forehead and around the nasal cavity. When you breathe through your nose, the nitric oxide in the paranasal sinuses follows the inhalation through the airways, down into the lungs and into the millions of microscopic sacs, known as alveoli, that supply the blood with oxygen. Research has shown that nitric oxide plays an important role in increasing blood oxygen and improving oxygen absorption by the lungs. Nitric oxide is also a vasodilator, which means that it increases blood flow and lowers blood pressure.
When you breathe through your mouth, the oxygen contained within that inhalation reaches the lungs. However, it gets there without the added health benefits of nitric oxide. It also gets there without the warming, added humidity or filtration provided by the nose. These all occur because a thin layer of moist tissue, known as the mucous membrane, lines the nose. The sticky surface of that membrane — the mucus — is quite efficient at capturing airborne particles and preventing them from getting into the lungs. The mucous membrane also contains specialized immune cells and enzymes to neutralize potential pathogens. And it’s lined with tiny hairlike structures, called cilia. These cilia constantly wave and beat and move mucus, along with debris trapped within it, away from the lungs and down into the throat for removal.
We think it’s important for you to learn the reason for your ongoing nasal congestion. It may be due to allergies or infection; it could be a structural problem, like a deviated septum; or it could arise from a blockage, as from polyps. The good news is that allergies respond well to medication, and anatomical blockages can be surgically corrected. Something as simple as those nasal strips, which help keep the nasal canal open, can bring relief. We think it would be wise for you to see your family’s health care provider to learn and address the underlying cause for your ongoing nasal congestion.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.