Five top breathing tips to protect against the coronavirus - Conscious Breathing Institute

Five top breathing tips to protect against the coronavirus

The purpose of the article is to give concrete, effective breathing related advice on what you can do to strengthen your health and immune system to be able to fight the coronavirus better if you become infected.

Since the virus is spread via the air (ref 1) and settles in the airways, the way we breathe is important to highlight. In a single day, we breathe in as much as 10-20,000 liters of air. That is a huge amount, and since one liter weighs 0.1 gram it makes up 10-20 kilos of air, in other words about 10 times more than the amount of food we eat. The air contains lots of bacteria, viruses and other particles. In just one day, we inhale up to 100 billion of them according to research at the Karolinska Institute in Sweden. 

Face masks may give a false sense of safety

Using a face mask is a measure that is becoming increasingly popular. Many doctors, however, recommend NOT using a mask, as it simply does not provide effective protection against small airborne particles such as viruses. Since it is inconvenient, there is also an increased risk of often touching your face with your hands when correcting the mask. Another important consideration is that the most common masks only last for about 3-4 hours before they have to be replaced.

Even worse is that many people who are using a mask, especially children, open their mouths to breathe when using it (see the video below where Chinese parents have filmed their children). The increased air resistance that the mask imposes, probably makes the children feel that it is too hard to breathe through their noses, and because of that, open their mouths. As you can read further down in the article, nasal breathing is one of the most important breathing tips, so using a breathing mask may, at worst, be counterproductive by leading to a false sense of security, but instead, may increase the risk of being infected.

The top five breathing tips

In regards to creating a strong internal environment, there is far more to it than just muscles and willpower. It has been found that improving our breathing habits is very effective in strengthening our inner environment as it affects thoughts, emotions and our physical body and creates the inner calmness required for the immune system to work optimally. Below, are the five most important breathing tips for what you can do to protect and strengthen yourself:

  • 1. Breathe through your nose
  • 2. Hum
  • 3. Exercise with the Relaxator breathing retrainer
  • 4. Breathe through difficult emotions
  • 5. Do exercises that create open and well-functioning airways

1. Breathe through your nose

We have four important organs that are exposed to external threats: skin, stomach, nose and lungs. Our skin and stomach have an acidic pH, the skin about 5.5 and the stomach about 1.5-3, which gives effective protection. The lungs, on the other hand, have an alkaline pH of about 7.6, which is a must for enabling the oxygen we inhale to be transferred to the blood. This high pH prevents the lungs from being protected from external particles in the way the skin and stomach are. Because of this, the function of the nose is crucial for protecting the lungs.

The air we breathe in is full of bacteria, viruses, chemicals and other particles. About 75 % of all particles and viruses in the air are filtered out as they pass through the mucous membranes and cilia of our nose. If we breathe through our mouth, the air goes unfiltered into our lungs. In other words, we skip our body’s first line of defense against intruders.

The further down the trachea and into our lungs the particles from the inhaled air end up, the greater the risk of getting inflammation and infections. Given the lungs’ enormous absorption area of 50-100 square meters, about the size of a tennis court, it is critically important that they are kept free of viruses and bacteria.

So if we are taking protective measurements against the coronavirus, it is not enough to wash our hands if we, at the same time, have our mouths open and breathe in 10,000-20,000 liters of unfiltered air every day. It’s a bit like filtering mosquitoes and swallowing camels! You can say that it is as natural to breathe through your mouth as it is to eat through your nose.

Three important reasons why you should breathe through your nose:


Our nose can be compared to a highly efficient heat exchanger that warms up and moistens the air. When inhaling, our nose becomes cooled and dry as it moistens and heats the inhaled air, which is usually cooler than our body temperature. When we exhale, the temperature inside our nose is raised, and the area is moisturized by the 37 degree Celsius (98.6° Farenheit) temperature and 100% moist air being returned from the lungs. If we, on the other hand, breathe in through our nose and out through our mouth, the nose will not restore it’s warmth and moisture upon exhalation. And if we breathe both in and out through our mouth, our nose will be constantly cold and dry.

Research shows that the rhinovirus, which is known to cause colds and infections in the upper respiratory tracts, will multiply when the nose cools down. The colder it is in the nose, the more the immune system is suppressed, which will create a favorable environment for the rhinovirus to reproduce (ref 2). Now, we do not know exactly how the coronavirus behaves, but it is not inconceivable that a cold nose offers an environment that is favorable for this virus to also propagate.


Nitric oxide, or NO, is a very important substance produced in large quantities in the nasal sinuses, which was discovered by Eddie Weitzberg, Jon Lundberg and co-workers at the Karolinska Institute in Sweden, in the mid-1990s (ref 3). When we inhale through our nose, NO accompanies the inhaled air in order to dilate the bronchial tubes to allow the air to pass through easily.

Another important function of NO are its antimicrobial properties which kills viruses and bacteria that have escaped from the cilia inside our nose and throat. The coronavirus belong to the same virus lineage as SARS (Severe Acute Respiratory Syndrome). In a paper from 2005 the researchers concluded that nitric oxide inhibits the replication of the SARS virus (ref 4).

Additionally NO also causes the blood vessels inside our lungs to dilate, which allows oxygen to be transferred to our blood more easily. When we breathe in through the mouth, the air is not spiked with this important substance.


When we breathe through our nose the carbon dioxide pressure in our body increases, since nasal breathing slows down the respiration rate, and thereby more CO2 is retained in our body. CO2 has been used in food packaging since the 1930’s, because of its antibacterial effect, which prevents disease-causing bacteria from growing. Bread, cheese, chicken, and coffee, are some of the products that have 100 percent carbon dioxide added inside the packaging.

A study at the Karolinska Institute showed that the growth of staphylococci was 1,000 times higher when the bacteria were exposed to normal air for 24 hours, compared with exposure to air saturated with 100 percent CO2 (ref 5).

In an article in Nature from 2019 an Australian research group demonstrated how water that is exposed to carbon dioxide, is an efficient way to inactivate virus and bacteria (ref 6).

A Swedish research group led by Professor Jan van der Linden has in several publications showed how exposing open surgical wounds to 100% carbon dioxide reduces the risk of infection of the wound (ref 7).


Infections in the airways and pneumonia are important characteristics of the people infected by the coronavirus. Pneumonia is usually bacterial or viral. Even though it is speculation, as more research is needed, it is not unthinkable that the antibacterial and antiviral properties of NO and carbon dioxide have contributed to the fact that the three women below, thanks to improving their breathing, no longer experience any pneumonia or infections in the airways.

In a paper published in 1930 by the Yale professor Yandell Henderson and colleagues - The treatment of Pneumonia by inhalation of carbon dioxide, they continued the work of the Cambridge professors Meakins, Haldane and Priestly who 10 years earlier concluded in a paper that "the harmful effects of shallow breathing, which exaggerates the uneven distribution of air to the alveoli, the oxygen deficiency that occurs in acute lobar pneumonia is ascribed to the shallow and rapid breathing associated with that condition."

In the Henderson-study a virulent culture of pneumococci, type 2, was introduced through a bronchoscope into the right lungs of a series of narcotized dogs and inflated with water to shut off the air circulation. A severe attack developed and the animals not treated with inhalation of carbon dioxide died in a few days. If, however, shortly after the symptoms of pneumonia set in, the animals were placed in an atmosphere containing from 5 to 7 percent carbon dioxide, the collapsed and pneumonic areas of the lung cleared up to a large extent, and many made a complete recovery.

So in conclusion, in order for pneumonia to develop into a severe condition, the bacteria or viral infection is not enough, occulsion and collapsed airways is also a prerequisite, which can occur from a) mouth breathing so that the inhaled air isn't spiked with NO, b) shallow breathing so that the air doesn't circulate and c) overbreathing that leads to lack of carbon dioxide.

The researchers claim that not only is atelectasis (collapsed lungs) an important factor in pneumonia, but that inhalation of carbon dioxide proves an effective means of counteracting the atelectasis and reinflating the pneumonic lung.


“But I cannot breathe through my nose,” you may say. “It is often stuffy or the nasal passages are tight.” One of the effects of mouth breathing is that a nose that is not used will eventually stop working properly, much like the phrase “if you don’t use it, you lose it.”

Reduced airflow through the nose gives rise to lower air pressure, which over time will make the nasal passages regress and decrease in size, which was confirmed by a study on patients who had undergone laryngectomy and were breathing through the throat (ref 8). A stuffy or tight nose is often a sign that breathing is not optimal. In the nose, under the nasal turbinates, there is erectile tissue. As your breathing improves, the erectile tissue will decrease in size and the inside of the nose will feel less crowded.

The narrowing of airways and nasal passages and a stuffy nose is a logical adaptation as it is our body’s defense mechanism to maintain an optimal carbon dioxide pressure. Carbon dioxide is produced in the body, and virtually all carbon dioxide leaves the body through exhalation. In the event of a deficiency, the body tries to reduce the outflow by narrowing the airways.

As you begin to improve your breathing, breathe through your nose and build up more carbon dioxide in your body, your nose will automatically become less tight as the defense mechanism is no longer needed. Read more in the article – How to unblock a stuffy nose >>


To ensure that you only breathe through your nose when asleep, you can tape your mouth with Sleep Tape. It may sound strange, but I recommend everyone to try it. A good night’s sleep is vital to our health. During sleep our body heals, repairs and regenerates. How we breathe when we sleep is of great importance, especially given the large number of hours we sleep every night.

The feedback I frequently get is that people wake up more alert in the morning, sleep more calmly, don’t wake up during the night, and need less sleep. This is what one woman said: –My nose has been stuffy almost every morning, and I loved the tape from day one. Already on the first morning my nose was freer and I had slept really well. Will never stop taping my mouth!

If you sleep with an open mouth your breathing will automatically exceed your body’s needs. This low-grade form of hyperventilation not only causes oxygen deficiency but also increases the risk of getting unwelcome particles into the lungs. Taping your mouth at night is a remarkably simple and inexpensive way to ensure that your mouth stays closed and respiration occurs only through your nose. This will make your breathing at night work for you instead of against you.

You may think it sounds barbaric, or feel uncomfortable with the idea of applying tape to your mouth — a common reaction among the participants in my courses. The discomfort is generally just a mental block, and after trying it out for a few minutes most people find it to be completely harmless. If you do feel discomfort, I suggest you start to apply the tape during the day, for example 15 minutes before bedtime for a few evenings, in order to become more comfortable with the sensation. Read more in the article – Practical experience of taping your mouth at night >>

Don’t have any Sleep Tape? No problem, many use surgical tape which you can get from your local pharmacy. Even freezer tape and band aid will work according to some.

2. Hum to increase air circulation and NO production

The second tips is to hum. Impaired breathing leads to poor air circulation and lower pressure in the nose and sinuses, thus creating an environment beneficial for bacterial growth and inflammation. Studies done at the Karolinska Institute in Sweden show that a humming sound leads to a dramatic increase of the airflow in the sinuses. Further the levels of nitric oxide (NO) increases 15- to 20-fold by humming compared with quiet exhalation. NO is known to be broadly antifungal, antiviral and antibacterial.

Read more in the article – Humming can eliminate sinusitis >>

Here is a simple hum exercise.

  • 1. Close your mouth and let the front part of the tongue rest in its natural place in the roof of the mouth, behind the front teeth.
  • 2. On exhalation say, ”Hmmm…” In other words, push together your vocal cords and squeeze the air out through your nose so that a humming sound occurs.
  • 3. You can feel the vibrations slightly in your jaw. The vibrations increase the air circulation and the production of NO in your nose and sinuses.
  • 4. In a chronically blocked nose or sinusitis repeat for 20-40 breaths (approx. 5-10 minutes) 2-4 times a day for a few days or until the problems are resolved.

To increase the effect you can, while humming, massage the area around your nose, temples and above your eyes (since we have sinuses there as well). If you have a sore throat, you can massage your throat and the root of your tongue. The massage stimulates the blood circulation in these areas. The throat massage also stimulates the vagus nerve which is directly coupled to our rest and digest system (the parasympathetic part of the autonomic nervous system).

The exercise could also be done preventively, for example when you are about to get a cold, or just being in the mood to do it.

3. Improve your breathing with the Relaxator Breathing Retrainer

The Relaxator Breathing Retrainer provides an adjustable resistance on your outbreath so that your exhalation is prolonged. This lays the foundation for rhythmic, slow, low and small breathing. When you are breathing in a way that is not optimal, your body suffers from a lack of oxygen. Your brain, heart, muscles and eyes are all major consumers of oxygen, and poorer oxygenation has the greatest negative impact on these organs and functions. With the Relaxator, the air ends up in the midriff to a greater extent, which results in a more efficient oxygen uptake.

This is what one person said: “I have a cold and have had a stuffy nose and have not been able to sleep well the last nights because of that. Tonight, when I woke up for the fifth time, I decided to try using the Relaxator. Since I could not breathe in through my stuffy nose, I had to breathe in through my mouth and out through the Relaxator. After a while, my nose was cleared so that I suddenly could breathe through it. I continued for a while with the Relaxator, but soon enough I fell asleep and then slept all night!”

Don’t have a Relaxator? No problem, you can exhale through a straw, pursed lips or tighten the muscles in your throat and wheeze the air out, so called ujjay-breathing.

Five important benefits from using The Relaxator:



Our breathing muscles consist of the diaphragm, as you can see in the picture, as well as muscles in the abdomen, chest, neck and shoulders.

At rest, 70-80 percent of muscular activity at inhalation should be with your diaphragm, which makes it by far our most important breathing muscle. In fact, the heart and the diaphragm are the only two muscles in our body that never rest. They are constantly active, the heart with pumping blood and the diaphragm with moving the air in and out of our lungs.

When we use the Relaxator, the resistance on the exhale exercises the diaphragm and other breathing muscles. When they are working better, the gas exchange becomes more efficient.

The gas exchange, the process in which the body absorbs oxygen and gets rid of carbon dioxide, takes place in the alveoli in the lungs. When we are sitting or standing, there is, thanks to gravity, most blood in the lower part of our lungs. Most of the alveoli are also located in the lower parts. If the inhaled air ends up far down in our lungs, it will provide a more efficient gas exchange. The large amount of blood and alveoli facilitates for the oxygen to be transferred to our blood and the carbon dioxide to be transferred from our blood to our lungs for exhalation.


Breathing where the inhaled air ends up high up in the chest does not only provide an inefficient gas exchange. It also ensures that the air further down in the lungs becomes confined and stale, as it gets trapped because the air doesn’t circulate.

An optimal airflow in the lungs is like the water in a rippling creek. When the air gets trapped, which happens in narrow airways, mouth breathing and shallow breathing, the air is closer to the water in a pond, stagnant and stale.

When the air circulation deteriorates in our nose, sinuses and lungs, an environment is created that sets the stage for viruses and bacteria to multiply more easily. Resistance breathing with the Relaxator increases the pressure in our nose and sinuses, which leads to increased air circulation.


Why is it so common for us to get sick before weekends or holidays? Well, then we relax and reduce the internal stress, which, in turn, makes the immune system more active.

Our immune system is almost as complex as our nervous system, and its task is to neutralize invaders in our body. When we experience stress, our immune system is suppressed. This is why stress hormones are given to people who have undergone organ transplants. As the new organ is perceived as an invader, the role of the stress hormones is to weaken the immune system to the point where it doesn’t repel the organ.

An extreme example can be found in the book Man’s Search for Meaning by Viktor Frankl, who survived three years in concentration camps. When he was deported to Auschwitz, it began with a four-day train journey in a narrow carriage and only one meal during the long journey. When they arrived 90% of the new arrivals were sent directly to the gas chamber. The 10% not selected for death would experience the intense stress of witnessing the execution of their fellow men and women seen in meter-high flames of fire bursting out of the chimneys. Those who survived would have to undress and have their entire body shaved while standing outside in the late autumn cold stark naked and wet after the shower. There was the heavy and dark awareness that the slightest offense would lead to immediate hanging. After experiencing all of this stress during the day their sleeping conditions were extremely unfavorable with nine people in a 2 x 2.5 meters bunk. Despite these extreme physical and mental stresses, they would wake up the next day without even having got a cold. Why? Because the extreme stress suppressed their immune system.

When you exhale through the resistance of the Relaxator, exhalation is prolonged, which reduces stress. Exhalation is linked to relaxation, and by prolonging exhalation your body’s ability to relax and ease off is increased. An extended exhalation will also have a positive effect on our inhalation, as the air reaches the lower parts of our lungs. The breathing also slows down. Low and slow breathing is the opposite to the shallow and rapid breathing that is strongly associated with stress.


A system that depends on the movement of the diaphragm is the lymphatic system. All organs in our abdomen emit waste products, and our lymphatic system, which is an important part of our immune system, has the task of removing the waste. We have more lymphatic fluid than blood in our body, but unlike our blood, which is pumped around the body by our heart; our lymph fluid lacks its own pump, which is why lymphatic fluid is dependent to a large extent on muscular activity. Therefore, the movement of our diaphragm is very important for our lymphatic system, especially since it never rests and is working 24/7.

When you are breathing fast and shallowly, the pressure in your midriff decreases, which impairs your posture. This becomes particularly obvious when sitting down, which many of us are doing way too much. As we’ve mentioned before, chest breathing leads to a reduction in blood oxygenation. When the movement of our diaphragm is reduced, the ability of our lymphatic system to remove residual products from the abdomen is also diminished.


The part of the nervous system that controls involuntary functions, such as muscles in the blood-vessels and airways, heartbeat and digestion, is called the autonomic nervous system. It is divided into a sympathetic, activating part and a parasympathetic, calming part.

The sympathetic part prepares the body for increased activity and is active during fight or flight response. The parasympathetic part influences rest, recovery and energy saving.

High sympathetic activity is like driving down the freeway at 80 miles per hour (130 km/h); we have tunnel vision, and to a large extent we react instinctively to what is happening. We end up in conflicts more easily and view the world through glasses that make us perceive it as threatening, and we feel worried and afraid.

If we, in our daily lives, operate mainly from sympathetic stimulation, it means that we are spending more energy than necessary. We all know what it’s like to be sick and powerless. The reason is that all our energy is used by the immune system to fight the invaders that make us sick. Breathing retraining with the Relaxator is an effective way to unlock the turbo so that we do not engage our stress system more than necessary and, thus, can save energy so that the immune system can do its job.


How do you normally deal with incoming stimuli? Imagine taking an ice cold shower. Do you fight the water entirely, or do you have a coping-strategy so that you are able to whiststand the cold water, or do you actually have the ability to explore, embrace and welcome them?

4. Breathe through difficult emotions

The fourth tip is to breathe through difficult emotions. There is a very interesting connection between how we breathe and trauma and unpleasant, unprocessed emotions that we have experienced. Expressions such as butterflies in my stomach and stress stomach indicate that the painful feelings are often situated in our stomach-area. The reason why many of us have a shallow chest breathing is simply to avoid getting in touch with grief, fear, anger and so on. Moving up our breath into the chest is an attempt to “run away” from the unpleasant feelings often situated in our abdominal area.

When we are afraid, tensed up and worried, another common breathing pattern is to breathe in and hold our breath. It is a natural reflex as our body prepares to meet a perceived danger. The expression “The danger is over, so now we can exhale” as we sigh in relief, reflects this breathing pattern well.

In the short term, it is a survival strategy as we are unable to deal with the painful emotions that seem overwhelming. In the long run, it is, however, not a particularly wise strategy.


What is the price for holding back emotions or dwelling on old conflicts? Clearly, it is not free. Far from it.

– What will happen if I’m holding out my hand for a while? – Nothing.

– Exactly, but what will happen if I am holding out my hand for an hour? – You will get tired.

– Yes, and what will happen if I am holding out my hand for a day? – You will get super tired and get cramps.

– Mmm, with all certainty. What if instead of an empty hand I am holding out a kettlebell that weighs 10 kg? – You will get really tired after just a little while!

– Exactly.

This is how your body works. It wastes a lot of energy when you hold on to anger, worry, grief, fear, traumas and so on. The more powerful they are, the more energy they will consume.

There is a price to pay to try to be one step ahead in order to avoid people and situations that may trigger fear, worry etc. And all the junk food, cigarettes, alcohol, drugs and so on that we consume to deafen what is fretting inside us also has a price tag. The energy leakage suppresses our immune system, as it is such a large consumer of energy.

When we are afraid and worried, we also get stressed, which weakens our immune system even more. Read more about how your fears can be crippling energy thieves in the article how I conquered my fear of public speaking.


In an interesting study, the participants were divided into two groups, where one group was instructed to hold back their emotions while the other group was encouraged to stay in touch with their emotions. Then, they got to see the same movie.

After the movie, they were asked to squeeze a hand strengthener as many times as they could. It turned out that those who held back their emotions were significantly weaker than those who had stayed in touch with them. In other words, we are leaking energy when we are holding back what we really believe, think and feel.

You’ll find more information in the article – Breathe through difficult emotions >>


Safe to upgrade is a simple, yet very powerful exercise in order to upgrade your fears and other dfficult emotions so that your response will be more relaxed and calm. Don't repel, reject, or run away from anger, grief, trauma, stress, and inner conflicts. Don't apply positive thinking. Instead, allow the negative aspects. Amplify them. Try to understand them. Be curious. Where do they come from? Do they bring some kind of message? Accept them. Forgive them. Embrace them. Upgrade them. Be thankful for them.

Inhalation is connected to fight/flight whereas exhalation is tied to calm/safe.

  • 1. AMPLIFY: You can do the exercise when sitting up or laying down, for example in bed before falling asleep or before getting up in the morning. Whenever something difficult comes up, just grab it an amplify it by taking a big breath in, holding your breath for as long as you can while at the same time tense up your body.
  • 2. RELAX: When you can't hold your breath any longer, just exhale and relax.
  • 3. UPGRADE: Breathe low, slow, relaxed and rhythmically in and out through your nose for a few minutes. The main task of your nervous system is to protect you and satisfy your needs. You are now safe and calm. Allow whatever needs to be upgraded to a more enlightened version of yourself

5. Exercises to create open and well-functioning airways

The six exercises below aim to open your airways, get them functioning well and strengthen and relax your breathing muscles. Pick a few exercises that appeal to you and put together your own 10-minute workout program. You can do your exercises daily or at times that are convenient for you.

Add a few calm breaths between the exercises, and reflect on how it feels in your body before moving on to the next practice. Keep your back erect and straight during the exercises, as this facilitates the work of the diaphragm and lowers the breathing. Breathe in a relaxed way, taking slow, low, calm, and rhythmic breaths.

It is an advantage to use the Relaxator as it helps you maintain good breathing during the exercises. The exercises will help you improve the way you breathe in your daily life, where you are breathing more and more of the daily 20-25,000 breaths in accordance with the seven good habits of Conscious Breathing: nose, abdominal, slow, small, upright posture, rhythmic and quiet. If you manage to maintain an upright posture with relaxed breathing during these exercises, chances are that you will manage this in more and more situations in your everyday life.



Scientific references

1) Study: Evidence of airborne transmission of the severe acute respiratory syndrome virus

Title Evidence of airborne transmission of the severe acute respiratory syndrome virus. Link to full text
Journal N Engl J Med. 2004 Apr 22;350(17):1731-9
Author Yu IT1, Li Y, Wong TW, Tam W, Chan AT, Lee JH, Leung DY, Ho T
Abstract BACKGROUND:There is uncertainty about the mode of transmission of the severe acute respiratory syndrome (SARS) virus. We analyzed the temporal and spatial distributions of cases in a large community outbreak of SARS in Hong Kong and examined the correlation of these data with the three-dimensional spread of a virus-laden aerosol plume that was modeled using studies of airflow dynamics.

METHODS:We determined the distribution of the initial 187 cases of SARS in the Amoy Gardens housing complex in 2003 according to the date of onset and location of residence. We then studied the association between the location (building, floor, and direction the apartment unit faced) and the probability of infection using logistic regression. The spread of the airborne, virus-laden aerosols generated by the index patient was modeled with the use of airflow-dynamics studies, including studies performed with the use of computational fluid-dynamics and multizone modeling.

RESULTS:The curves of the epidemic suggested a common source of the outbreak. All but 5 patients lived in seven buildings (A to G), and the index patient and more than half the other patients with SARS (99 patients) lived in building E. Residents of the floors at the middle and upper levels in building E were at a significantly higher risk than residents on lower floors; this finding is consistent with a rising plume of contaminated warm air in the air shaft generated from a middle-level apartment unit. The risks for the different units matched the virus concentrations predicted with the use of multizone modeling. The distribution of risk in buildings B, C, and D corresponded well with the three-dimensional spread of virus-laden aerosols predicted with the use of computational fluid-dynamics modeling.

CONCLUSIONS:Airborne spread of the virus appears to explain this large community outbreak of SARS, and future efforts at prevention and control must take into consideration the potential for airborne spread of this virus.

2) Study: Cold nose creates favourable environment for the rhinovirus

Title Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells. Link to full text
Journal Proceedings of the National Academy of Sciences (PNAS), Jan-2015
Author Iwasaki A et al
Significance Rhinovirus is the most frequent cause of the common cold, as well as one of the most important causes of asthma exacerbations. Most rhinovirus strains replicate better at the cooler temperatures found in the nasal cavity than at lung temperature, but the underlying mechanisms are not known. Using a mouse-adapted virus, we found that airway epithelial cells supporting rhinovirus replication initiate a more robust antiviral defense response through RIG-I–like receptor (RLR)–dependent interferon secretion and enhanced interferon responsiveness at lung temperature vs. nasal cavity temperature.

Airway cells with genetic deficiencies in RLR or type I interferon receptor signaling supported much higher levels of viral replication at 37 °C. Thus, cooler temperatures can enable replication of the common cold virus, at least in part, by diminishing antiviral immune responses.
Abstract Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33-35 °C) than at core body temperature (37 °C). To gain insight into the mechanism of temperature-dependent growth, we compared the transcriptional response of primary mouse airway epithelial cells infected with rhinovirus at 33 °C vs. 37 °C.

Mouse airway cells infected with mouse-adapted rhinovirus 1B exhibited a striking enrichment in expression of antiviral defense response genes at 37 °C relative to 33 °C, which correlated with significantly higher expression levels of type I and type III IFN genes and IFN-stimulated genes (ISGs) at 37 °C. Temperature-dependent IFN induction in response to rhinovirus was dependent on the MAVS protein, a key signaling adaptor of the RIG-I-like receptors (RLRs). Stimulation of primary airway cells with the synthetic RLR ligand poly I:C led to greater IFN induction at 37 °C relative to 33 °C at early time points poststimulation and to a sustained increase in the induction of ISGs at 37 °C relative to 33 °C.

Recombinant type I IFN also stimulated more robust induction of ISGs at 37 °C than at 33 °C. Genetic deficiency of MAVS or the type I IFN receptor in infected airway cells permitted higher levels of viral replication, particularly at 37 °C, and partially rescued the temperature-dependent growth phenotype. These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.

3) High nitric oxide (NO) production in nasal sinuses

Title High nitric oxide production in human paranasal sinuses.
Journal Nat Med. 1995 Apr;1(4):370-3.
Author Lundberg JO, Farkas-Szallasi T, Weitzberg E, Rinder J, Lidholm J, Anggåard A, Hökfelt T, Lundberg JM, Alving K.
Abstract Nitric oxide (NO) is present in air derived from the nasal airways. However, the precise origin and physiological role of airway-derived NO are unknown. We report that NO in humans is produced by epithelial cells in the paranasal sinuses and is present in sinus air in very high concentrations, close to the highest permissible atmospheric pollution levels.

In immunohistochemical and mRNA in situ hybridization studies we show that an NO synthase most closely resembling the inducible isoform is constitutively expressed apically in sinus epithelium. In contrast, only weak NO synthase activity was found in the epithelium of the nasal cavity. Our findings, together with the well-known bacteriostatic effects of NO, suggest a role for NO in the maintenance of sterility in the human paranasal sinuses.

4) Nitric Oxide Inhibits the Replication Cycle of Severe Acute Respiratory Syndrome Coronavirus

Title Nitric Oxide Inhibits the Replication Cycle of Severe Acute Respiratory Syndrome Coronavirus Link to full text
Journal J Virol. 2005 Feb; 79(3): 1966–1969
Author Sara Åkerström, Mehrdad Mousavi-Jazi, Jonas Klingström, Mikael Leijon, Åke Lundkvist, and Ali Mirazimi1
Abstract Nitric oxide (NO) is an important signaling molecule between cells which has been shown to have an inhibitory effect on some virus infections. The purpose of this study was to examine whether NO inhibits the replication cycle of the severe acute respiratory syndrome coronavirus (SARS CoV) in vitro.

We found that an organic NO donor, S-nitroso-N-acetylpenicillamine, significantly inhibited the replication cycle of SARS CoV in a concentration-dependent manner. We also show here that NO inhibits viral protein and RNA synthesis.

Furthermore, we demonstrate that NO generated by inducible nitric oxide synthase, an enzyme that produces NO, inhibits the SARS CoV replication cycle.

5) Study: Carbon dioxide inhibits bacterial growth rate

Title Carbon dioxide inhibits the growth rate of Staphylococcus aureus at body temperature Link to full text
Journal Surgical Endoscopy And Other Interventional Techniques volume 19, pages 91–94(2005)
Author M. Persson, P. Svenarud, J.-I. Flock & J. van der Linden
Abstract BACKGROUND:Since the 1930s, carbon dioxide (CO(2)) has been combined with cold storage for the preservation of food. However, its use for the prevention of surgical wound infection was long considered to be impractical. Now CO(2) is widely used during laparoscopic procedures, and a method has been developed to create a CO(2) atmosphere in an open wound. The aim of this study was to investigate the effect of CO(2) on the growth of Staphylococcus aureus at body temperature.

METHODS:First, S. aureus inoculated on blood agar were exposed to pure CO(2) (100%), standard anaerobic gas (5% CO(2), 10% hydrogen, 85% nitrogen), or air at 37 degrees C for a period of 24 h; then a viable count of the bacteria was made. Second, S. aureus inoculated in brain-heart infusion broth and kept at 37 degrees C were exposed to CO(2) or air for 0, 2, 4, 6, and 8 h; then the optical density of the bacteria was measured.

RESULTS:After 24 h, the number of S. aureus on blood agar was about 100 times lower in CO(2) than in anaerobic gas (p = 0.001) and about 1,000 times lower than in air (p = 0.001). Also, in broth, there were fewer bacteria with CO(2) than with air (p < 0.01). After 2 h, the number of bacteria was increased with air (p < 0.001) but not with CO(2) (p = 0.13). After 8 h, the optical density had increased from zero to 1.2 with air but it had increased only to 0.01 with CO(2) (p = 0.001).

CONCLUSION:Pure CO(2) significantly decreased the growth rate of S. aureus at body temperature. The inhibitory effect of CO(2) increased exponentially with time. Its bacteriostatic effect may help to explain the low infection rates in patients who undergo laparoscopic procedures.

6) Study: Virus and bacteria inactivation by CO2 bubbles in solution

Title Virus and bacteria inactivation by CO2 bubbles in solution Link to full text
journal Nature partner journals: Clean Water volume 2, Article number: 5 (2019)
Author Adrian Garrido Sanchis, Richard Pashley & Barry Ninham
Abstract The availability of clean water is a major problem facing the world. In particular, the cost and destruction caused by viruses in water remains an unresolved challenge and poses a major limitation on the use of recycled water. Here, we develop an environmentally friendly technology for sterilising water. The technology bubbles heated un-pressurised carbon dioxide or exhaust gases through wastewater in a bubble column, effectively destroying both bacteria and viruses. The process is extremely cost effective, with no concerning by-products, and has already been successfully scaled-up industrially.

7) Study: Carbon dioxide insufflation deflects airborne particles from an open surgical wound model

Title Carbon dioxide insufflation deflects airborne particles from an open surgical wound model Link to full text
Journal Journal of Hospital Infection Volume 95, Issue 1, January 2017, Pages 112-117
Author P.Kokhanenkoa, G.Papottia, J.E.Caterb, A.C.Lynchc, J.A.van der Lindend, C.J.T.Spencea
Abstract Background:Surgical site infections remain a significant burden on healthcare systems and may benefit from new countermeasures.

Aim:To assess the merits of open surgical wound CO2 insufflation via a gas diffuser to reduce airborne contamination, and to determine the distribution of CO2 in and over a wound.

Methods:An experimental approach with engineers and clinical researchers was employed to measure the gas flow pattern and motion of airborne particles in a model of an open surgical wound in a simulated theatre setting. Laser-illuminated flow visualizations were performed and the degree of protection was quantified by collecting and characterizing particles deposited in and outside the wound cavity.

Findings:The average number of particles entering the wound with a diameter of <5 mm was reduced 1000-fold with 10 L/min CO2 insufflation. Larger and heavier particles had a greater penetration potential and were reduced by a factor of 20. The degree of protection was found to be unaffected by exaggerated movements of hands in and out of the wound cavity. The steady-state CO2 concentration within the majority of the wound cavity was >95% and diminished rapidly above the wound to an atmospheric level (w0%) at a height of 25 mm.

Conclusion: Airborne particles were deflected from entering the wound by the CO2 in the cavity akin to a protective barrier. Insufflation of CO2 may be an effective means of reducing intraoperative infection rates in open surgeries.

8) Study: Dimension of nasal cavity reduced when not used

Title Influence of long-term airflow deprivation on the dimensions of the nasal cavity: a study of laryngectomy patients using acoustic rhinometry
Journal Ear Nose Throat J. 2007 Aug;86(8):488, 490-2
Author Ozgursoy OB1, Dursun G
Abstract We conducted a prospective study to investigate the long-term effect of nasal airflow deprivation on nasal dimensions after total laryngectomy. We evaluated 48 patients who had an initial diagnosis of laryngeal cancer; 6 were disqualified during follow-up, leaving us with data on 42 patients for our final analysis. Acoustic rhinometry was used to measure the minimum cross-sectional area (MCSA) and the volume of the nasal cavity on both the left and right sides before and after laryngectomy. In addition, patients underwent endoscopic nasal examinations and answered questionnaires pre- and postoperatively.

At both the 1- and 2-year follow-ups, the mean MCSAs and the mean nasal volumes of both the left and right nostrils were significantly smaller than the preoperative values (p < 0.001). The endoscopic examinations revealed only a mild deterioration in the appearance of the nasal mucosa over the long term. Questionnaire responses obtained at the 2-year follow-up visit revealed that all 42 evaluable patients were experiencing a moderate degree of nasal obstruction while inhaling through the nose. Our data indicate that the dimensions of the nasal cavity appear to be substantially and permanently reduced after total laryngectomy.

Our study had two important advantages over other similar studies. First, because ours was a prospective study, we were able to obtain preoperative data and use it to make postoperative comparisons of the same patients rather than using healthy controls as comparators. Second, we used acoustic rhinometry, while most other studies relied on anterior rhinoscopy or rhinomanometry, which are inferior methods ofmaking the evaluations in question. We believe that our findings represent a substantial contribution to our knowledge of the physiologic and functional alterations of the nasal cavity that occur as a result of a complete cessation of nasal airflow.

9) Study: Humming and the production of nitric oxide (NO) and sinus airflow

Title Humming, nitric oxide and paranasal sinus ventilation. Link to full text
Journal Karolinska University Press 2006
Author Mauro Maniscalco
Abstract The paranasal sinuses are air-filled bony cavities surrounding the nose. They communicate with the nose via the sinus ostia through which fluid and gases pass in both directions. A proper ventilation is crucial for sinus integrity and blockage of the ostia is a major risk factor for development of sinusitis.

In this thesis we have explored an entirely new approach to monitor sinus ventilation – the nasal humming test. We show in human studies in vivo and in a sinus/nasal model that the oscillating airflow generated during humming produce a dramatic increase in sinus ventilation.

Interestingly, the increased gas exchange can be readily monitored on-line by simultaneously measuring the levels of the gas nitric oxide (NO) in nasally exhaled air. The sinuses constitute a major natural reservoir of NO and when gas-exchange increases during humming NO escapes rapidly into the nasal cavity thereby creating a highly reproducible peak in exhaled NO.

When exploring the different factors that determine the humming peak in NO we found that sinus ostium size was the most important but the humming frequency also influenced the sinus NO release. In patients with severe nasal polyposis and completely blocked sinus ostia the humming peak in NO was abolished. Moreover, in patients allergic rhinitis, absence of a NO peak was associated with endoscopic signs suggestive of ostial obstruction. In the last study we went on to study if an oscillating airflow could be used not only to wash gas out from sinuses but also to enhance passage of substances into the sinuses. Indeed, we found evidence of an intra-sinus drug deposition by adding a sounding airflow to an aerosol.

In conclusion, the ventilation of the paranasal sinuses increased greatly when a person is humming; a finding that could have both diagnostic and therapeutic implications. Measurements of nasal NO during humming may represent a test of sinus ostial function. In addition, aerosol in combination with a sounding airflow could possibly be useful to increase the delivery of drugs into the paranasal sinuses.

10) Study: Exhaled nasal nitric oxide (NO) during humming

Title Exhaled nasal nitric oxide during humming: potential clinical tool in sinonasal disease?
Journal Biomark Med. 2013 Apr;7(2):261-6. doi: 10.2217/bmm.13.11.
Author Maniscalco M1, Pelaia G, Sofia M.
Abstract The use of nasal nitric oxide (nNO) in sinonasal disease has recently been advocated as a potential tool to explore upper inflammatory airway disease. However, it is currently hampered by some factors including the wide range of measurement methods, the presence of various confounding factors and the heterogeneity of the study population. The contribution of nasal airway and paranasal sinuses communicating with the nose through the ostia represents the main confounding factor.

There is accumulating evidence that nasal humming (which is the production of a tone without opening the lips or forming words) during nNO measurement increases nNO levels due to a rapid gas exchange in the paranasal sinuses. The aim of this review is to discuss the basic concepts and clinical applications of nNO assessment during humming, which represents a simple and noninvasive method to approach sinonasal disease.

11) Study: The effect of daily humming on chronic rhinosinusitis

Title Strong humming for one hour daily to terminate chronic rhinosinusitis in four days: A case report and hypothesis for action by stimulation of endogenous nasal nitric oxide production. Link to full text
Journal In Medical Hypotheses 2006 66(4):851-854
Author Eby, George A.
Abstract Rhinosinusitis is an inflammation or infection of the nose and air pockets (sinuses) above, below and between the eyes which connect with the back of the nose through tiny openings (ostia). Rhinosinusitis can be caused by bacteria, viruses, fungi (molds) and possibly by allergies. Chronic rhinosinusitis (CRS) is an immune disorder caused by fungi. The immune response produced by eosinophils causes the fungi to be attacked, which leads to damage of the sinus membranes, resulting in full-blown rhinosinusitis symptoms. Gaseous nitric oxide (NO) is naturally released in the human respiratory tract. The major part of NO found in exhaled air originates in the nasal airways, although significant production of NO also takes place in the paranasal sinuses.

Proper ventilation is essential for maintenance of sinus integrity, and blockage of the ostium is a central event in pathogenesis of sinusitis. Concentrations of NO in the healthy sinuses are high. Nasal NO is known to be increased 15- to 20-fold by humming compared with quiet exhalation. NO is known to be broadly antifungal, antiviral and antibacterial. This case report shows that a subject hummed strongly at a low pitch (~130 Hz) for 1 h (18 hums per minute) at bedtime the first night, and hummed 60—120 times 4 times a day for the following 4 days as treatment for severe CRS.

The humming technique was described as being one that maximally increased intranasal vibrations, but less than that required to produce dizziness. The morning after the first 1-h humming session, the subject awoke with a clear nose and found himself breathing easily through his nose for the first time in over 1 month. During the following 4 days, CRS symptoms slightly reoccurred, but with much less intensity each day. By humming 60—120 times four times per day (with a session at bedtime), CRS symptoms were essentially eliminated in 4 days.

Coincidentally, the subject’s cardiac arrhythmias (PACs) were greatly lessened. It is hypothesized that strong, prolonged humming increased endogenous nasal NO production, thus eliminating CRS by antifungal means.

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