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Question & Answer - Oral Sensory-Motor, Myofunctional, Vocal Tract, & Airway Information

Why is nasal breathing important for good health?

Answer from Dr. Scott A. Simonetti, Dentist in New York, USA

August 2016


In 1999 Jon Lundberg’s Nasal nitric oxide in man described how the nasal passages are the first line of defense in our body, effectively cleaning and warming the air we breathe.  The nasal passage prepares the inhaled air for entry into the lungs.  By breathing through the mouth, we unfortunately bypass this first line of defense, allowing invaders to enter our lungs, which can initiate an immune response.

The nasal defense system involves several features.  The most important aspect is the production of the gas Nitric Oxide in the paranasal sinuses (Maxillary, Frontal, Ethmoid, and Sphenoid sinuses).  The concentration of Nitric Oxide continually produced in these sinuses is several hundred times higher than what is required to kill bacteria.  These high concentrations of Nitric Oxide not only function to keep the sinuses sterile, but they also help to kill invaders in the inhaled air.  Every breath through the nose draws out the Nitric Oxide from within the sinuses via small openings called Ostia, mixing with the inspired air as it travels down the trachea into the lungs.  This is the ideal method of breathing for humans.  Mouth breathing is a compensation which will eventually lead to pathology if not corrected.

When mouth breathing, the Nitric Oxide produced in the paranasal sinuses is not mixed with the inhaled air and pathogens remain alive. These pathogens now have an easier path into the body, and they can enter the pulmonary system.  These invaders will require an immune response from the lungs.  This response, which may or may not be strong enough to avoid a respiratory infection, could have been avoided by nasal breathing.  Frequent respiratory and sinus infections are characteristic of mouth breathers.  Even if an infection does not occur from mouth breathing, the additional immune response is taxing to the system.  Frequent, overused immune responses can begin a viscous cycle of inflammation and pain that lasts for months or years.  The immune system has an amazing adaptive response that protects us well, but when overused can become pathological.

Not only does nasal breathing protect the body from pathogens, it also helps to remove dust, mildew, mold, animal dander, smoke, and other irritants from the inhaled air.  It also warms and humidifies the inhaled air to a perfect temperature and moisture level for optimal lung conditions.  Once again, mouth breathing bypasses this conditioning (warming and moisturizing) of the inspired air and allows unfavorable air to reach deep within the lungs.

But there is more…. Nitric Oxide from inhaled nasal air acts as a potent bronchodilator!  That means that Nitric Oxide allows for improved oxygen utilization/exchange within the lungs.  Mouth breathing does not utilize Nitric Oxide, and therefore, optimal bronchodilation does not occur.  Without Nitric Oxide entering the lungs as a bronchodilator, lower oxygen saturation levels may occur in the blood which can be very dangerous for organs such as the heart, brain, kidney, intestines, and liver.

In addition to Nitric Oxide acting on pathogens, the nasal passage is also lined with cilia, microscopic projections that trap and remove dust and pathogens from the inspired air as it flows through the nasal passages.  These cilia also contain a layer of mucus that protects the cilia from drying out.  The mucus traps debris and pathogens.  It contains immune components such as antibodies and white blood cells ready to defend the body from any inhaled invader.  In order for the mucus to reach the throat (we normally swallow one gallon of nasal mucus each day!), the cilia beat in a rhythmic motion directing trapped pathogens and debris.  If mucus is not cleared by normal nasal breathing and swallowing, then it can accumulate in the sinuses.  This accumulation can cause pain, congestion and infections. 

The proper flow of Nitric Oxide from the paranasal sinuses into the nasal passages and eventually the lungs is important to keep the cilia and mucus layers functioning properly to ensure a proper first line of defense.  Mouth breathing disrupts the normal function of Nitric Oxide, the cilia, and mucus clearance.  Nasal breathing, day and night, is vital for good health.

If you notice your child has enlarged tonsils, snores, complains of fatigue, or is a mouth breather, please have him or her evaluated by an ENT (otolaryngologist), Dentist, or Sleep Specialist.  By identifying and then correcting the cause of mouth breathing in childhood, the person will less likely develop into a mouth breathing adult who is susceptible to pathogens and disease.  Bypassing the first line of defense (i.e., nose breathing) is not the prescription for a healthy life!

About the Author

Scott A Simonetti DDS has a Nutritional Sciences degree from Cornell University and a DDS from the University at Buffalo School of Dental Medicine.  He is in private practice in East Islip, New York with a specific interest in Airway, TMD, and Dental Sleep Medicine.  He lectures on Nasal Breathing, Nitric Oxide, and Mitochondria, and is the founder and CEO of Advanced Facialdontics LLC, an oral orthotic company. Email: