Healthy air humidity (Part 3)

In this technical paper by Nortec, we continue looking at the importance of air humidification in hospitals and in outpatient settings, specifically focusing on the importance of water to the human body and the negative effects of dry air.

Part 1 - Healthy air humidity
Part 2 - There might be a serial-killer in our hospitals!

The human body consists of 75% water

The human body mainly consists of water. At birth, our bodies are made up of 80% water. This reduces throughout our lives, amounting to about 70% in adults and reducing to only 55% at age 85.

The majority of it is stored in our bodies’ cells, about one third in the extracellular space, the area outside the cells which is filled with fluid, and in the blood.

Water regulates the functioning of the cardiovascular system and digestion, is a solvent for salt and minerals, means of transport for nutrients and degradation products. For our metabolisms to function, the body has to have enough water available at all times.

Our brains also need water all the time to think. In what is surely the most important organ of the body, brain matter is made up of 85 to 90% water.

Water fulfils another important function in heat regulation. Two to three litres of water are lost per day through sweating, breathing and our excretions. If this value is higher in sick people, the water balance has to be monitored by a doctor and if necessary liquids introduced intravenously to avoid dehydration. A lack of water can lead to life-threatening states.

Unlike camels in the desert, we are unable to store water for long periods. Therefore, each loss of water must be balanced out on a daily basis through nutrition and the intake of liquids, in illness this can occur by means of infusions if necessary. Otherwise our bodies react with sensitive disruptions. We feel thirsty even at liquid losses of 0.5%. At 2%, the physical and mental operational capacity is reduced. From 5%, our body temperatures increase, and in the event of a loss of water of 10% of our body weight, severe symptoms such as blood thickening, confusion or circulatory failure may occur. Through failures of the nervous and circulatory systems, a deficit of over 20% leads to death.

Note: We can survive without food for about four weeks depending on fat reserves, but we can only survive without water for a few days. A desert climate significantly accelerates this process. Excessively dry atmospheric air for prolonged periods is similar!

PG13Our bodies are made up of mostly water and excessively dry atmospheric air for prolonged periods can be very harmful to the body.

The effects of dry air

Dissemination of viruses in dry air: There are three ways in which we can get infected by viruses: The exchange of body fluids, smear infection; or droplet infection.

Droplet infection occurs through the air, for example through the breathing, speaking, sneezing or coughing of a sick person. When this happens, thousands of small droplets are released into the ambient air. Within split seconds, they shrink by 90% of their volume and adapt to the ambient conditions. At this point, it is important the ambient air humidity is right so that the saline solution does not get oversaturated and crystallisation does not occur. Thus, the droplet remains moist and disease-causing agents it contains become inactive within a short period of time. Otherwise, a tiny, floatable droplet encased in a salty crust is formed. The saline solution within this crust would be an environment in which viruses and bacteria can survive. These structures are so light that they float around like invisible spaceships in search of another host in order to penetrate its cells. And this happens at home, in the office, in the doctor’s practice, or in a hospital.

If healthy people inhale infected atmospheric air or come in direct contact with infectious people, the highest alert level is necessary. This is because, whenever anybody inhales these contaminated aerosol droplets via his or her moist airways, the salty crust dissolves immediately on contact with the persons’ body fluids. This gives viruses the chances to penetrate cells of the body and cause an infection. However, we now know that especially viruses, which cause many infections especially in winter, cannot withstand moderately moist air of 40 to 60% humidity and within a few minutes no longer pose a threat. And when you think that we spend the majority of our lifetimes in buildings, you realise that we also share the air we breathe with all those in the same place. So, we can conclude that the air we breathe is our main means of contact, although we don’t know what it contains at any point in time.

Lifespan of viruses: Viruses are our constant companions. We come in contact with them on a daily basis without getting sick. They stick to objects and can get into the body through contact with our hands. In most cases, a healthy immune system kills them off – usually without us even noticing. Unlike bacteria, viruses are not living things. In simple terms, they consist of genetic material within a shell. They cannot reproduce themselves. For this reason, they need a host cell in which they implant their genetic information and which they reprogramme and can then reproduce themselves. The healthy cell is destroyed in the process. If our immune system is weakened, we get sick.

Outside of their host, viruses generally remain effective only for a few seconds. It depends to a large extent on the temperatures and the air humidity. They dislike warmer conditions above 20°C as much as they do a relative air humidity between 40 and 60%. On the contrary, low temperatures and particularly a low air humidity offer ideal atmospheric conditions for the viruses themselves or for aerosols occupied by viruses to remain active over the course of several days.

Brain: Our cerebrum and cerebellum make up only 2% of the body. Nevertheless, we need 20% of our blood for a sufficient oxygen supply alone. Brain cells consist of 85% water. The majority of the energy needed for thinking is generated there through a hydroelectric process. This is why, after a certain length of time, a lack of water in the body means that too little energy is available to us. As a result, many vital functions are suppressed. A low energy level in turn means that physical and mental tasks can hardly be completed over longer periods of time.

Eyes: Our eyes are supplied with nutrients and oxygen through the tear film. In addition, bodily substances with disinfectant properties for defence against viruses and bacteria are transported or foreign bodies washed off. To do this, our eyelids wipe the eyes every four to six seconds, before the existing tear film breaks down.

If the formation of tears is impeded however, or their composition is no longer correct, the tear film gets stripped away despite the closing of the lids. Dry patches occur on the eye, which lead to itchiness or even infections. Eye drops provide only short-term relief and are therefore not a long-term solution.

Immune defence : Our immune defence truly is a marvel. It protects a healthy body from the infiltration of viruses, bacteria and other undesirable particles or germs in a natural way. Above all, our noses are called on to do this work. Breathing occurs mainly through our organ of smell. We breathe in mostly through the nose and, especially when talking, out through the mouth. Via the airways, our ambient air sweeps into the lungs and into the tiniest end-organs, the alveoli.

The entire way there is coated with mucous membranes, which excrete a fluid on a continuous basis. Part of it has hairy protrusions. Together with the mucous membranes, these cilia form the respiratory epithelium. It is constantly in motion and is often compared with a field of corn stalks swaying in the wind. This constant motion ensures that impurities and disease-causing agents inhaled in the air we breathe are blended with mucous and then carried away before an infection can occur. Like an air-conditioning system, our nose cleans the air, heats it to 37°C and ensures a 100% humidification and steam saturation. This is the only way the air can access our alveoli. Otherwise oxygen absorption would not be possible.

Breathing in excessively dry air compromises the functioning of the respiratory epithelium. The mucous no longer obtains enough water and moisture and as a result thickens, no longer runs off and breaks down. The self-cleaning effect only works inadequately. This opens the floodgates for viruses and bacteria. Our immune defence therefore needs optimum moisture conditions for us to stay healthy.

Skin: With a surface of about 2m², the skin is our largest organ. It protects us from cold, heat and radiation, resists pressure and impact, with its slightly acidic pH value of 5.7 keeps germs and microorganisms at bay, and is our primary item of clothing for heat insulation. Its structure can be seen under the microscope.

There are three layers: The epidermis with a corneal layer, the dermis and the subcutaneous layer. The skin is also our largest sensory organ, supports breathing and is cooling when we perspire. All in all, the skin is multi-functional, combines water and fat tissues and provides an external barrier. If the ambient conditions are right, it remains elastic as it does so.

However, if the skin loses moisture and fats, this barrier crumbles. Dry ambient air may favour this process, if the body itself can no longer obtain enough from inside to compensate. This can be the case in sick or older people especially. The same goes for infants whose skin is not yet fully formed. In these cases, the corneal layer becomes increasingly porous and loses its protective function more and more. At the same time, dangerous substances can penetrate more easily which leads to skin irritations and inflammations.


To be continued

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