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  5. Humidity: humidity: natural health protection and hygiene for indoor air

Humidity: natural health protection and hygiene for indoor air

A relative humidity of 40 - 60% reduces the risk of droplet infection

Optimally humidified room air protects you, your family and also your employees at the workplace from viruses that cause illness and at the same time strengthens the natural mechanisms of the body's immune system - our strongest weapon against viruses and germs that cause illness and germs in the air we breathe. In the following text, you will learn everything you need to know about how to use a humidifier to significantly minimise the risk of droplet infection (in times of rampant epidemics and pandemics the most common type of infection in influenza and other viral infections).


Optimally humidified room air kills viruses

Sneezing is contagious and problematic in several ways! If an infected person sneezes or coughs in a closed room, thousands of infectious droplets of germs are explosively ejected into the ambient air and sometimes remain there for a long time as highly infectious suspended particles. These germ droplets, also known as aerosols, form a conglomerate of the specific pathogen, water and salts, whose viability in the ambient air is decisively impaired by the prevailing humidity.

According to the „New England Journal of Medicine“, scientists have investigated how long the novel SARS-CoV-2 is viable outside the host body. In germ droplets (aerosols), SARS-CoV-2 could be detected for more than 3 hours, on various surfaces the half-life is even up to 72 hours.

Air humidity between 40 - 60% r.h.: Viruses die within seconds

If pathogens are coughed up or sneezed out by an infected person into an optimally humidified room air with 40 - 60% relative humidity, the salt concentration within the droplet changes in such a way that the pathogen is killed immediately after contact with the air.

The floating time and infectiousness of the germ droplet is minimized to a few seconds, while the risk of infection is low!

Air humidity < 40 - 40% r.h.: Germs are preserved and remain infectious for a long time

Excessively dry room air below 40% RH, however, has exactly the opposite effect. The droplet, which has been coughed up or sneezed out, dries up, whereby the crystallised salts preserve the actual pathogen.

The aerosol, which has been shrunk by dehydration, floats through the room air for many hours and remains highly infectious during this time!


Effects of air humidity on the infectivity of viruses

It is not uncommon to get disapproving looks when coughing or sneezing in closed rooms, even from a distance of several meters. The fear of a possible infection is usually greater than the knowledge of the connection between room air humidity and the infectivity of germs. In the following lines, you will learn how the risks of droplet infection in closed rooms can be considerably minimized with optimum humidity. Germs droplets are released into the indoor air via the respiratory tract of infected persons when sneezing or coughing and can infect persons present during their period of suspension by inhaling the aerosol particle. It is not important to know "whether" the germ is infectious, but "how long"! Because the room air humidity plays a decisive role in the survivability and floating behaviour of aerosols!

Dry air (0 - 39% r.h.) keeps viruses infectious for a long time

Excessively dry room air in the corridor from 0 to 39% R.H. increases the risk of infection from airborne aerosols.

  • High hovering time in the air
  • Pathogens in the aerosol are preserved by crystallised salts
  • Pathogens remain infectious in the room air

Optimally humidified air (40 - 60% RH) kills viruses

A room air humidity of 40 - 60% r.h. represents an extremely unfavourable environment for pathogens and reduces the risk of infection to a minimum!

  • Low hovering time in the air
  • Pathogens in the aerosol are killed by increased salt concentration
  • Pathogens are killed in the room air

Excessively humid air (60 - 100% r.h.) keeps viruses infectious

Excessively humid room air in the corridor from 60 to 100% r.h. makes aerosols inert, but does not affect infectivity.

  • Low hovering time in the air
  • Increased volume and weight of the aerosol
  • Pathogens remain infectious in the room air

Optimally humidified room air: doping for the immune system

The human body is not defenceless against the dangers of viruses and bacteria. The sophisticated protective mechanisms of the respiratory tract are a central component of the body's own defences and provide effective protection against pathogens in the air we breathe when the mucous membranes of the nose and throat are optimally moistened. If, on the other hand, excessively dry room air prevents the functionality of these protective mechanisms, pathogenic germs enter the body almost unhindered.

Air humidity is the fuel for the human immune system

Everybody knows that! Excessively dry room and heating air irritates the sensitive mucous membranes of the nose and throat, causes coughing, hoarseness and literally dries out our immune system. This, in turn, increases the risk of infection with pathogenic germs and viruses. But why does this happen?

The respiratory mucosa plays a major role in our defence against viruses and bacteria. It filters out the smallest pathogens (bacteria, fungi or viruses) from the air with each of our approx. 20,000 breaths per day and thus prevents these harmful germs from entering the body.

Damp mucous membranes are the protective shield against pathogenic germs

The respiratory mucosa consists of a ciliated epithelium, which is best imagined as a veritable carpet of millions of movable hairs. Between these cilia, mucus-forming goblet cells continuously produce a watery mucus that protectively covers the entire cell carpet and keeps it permanently moist. In this moist protective film, the cilia move up to 1,000 times per minute in waves towards the throat and also serve as a natural conveyor belt to transport adherent viruses and bacteria. Even the smallest microparticles get caught in this moist environment, are swallowed down with the mucus and killed.

If the air in the room is too dry, this natural protective mechanism comes to a standstill

Excessively dry room air withdraws the necessary water from the mucus layer, so that the previously protective slime layer becomes hard and loses its adhesiveness. The infectious pathogens no longer get caught and can continue their way into the body unhindered. At the same time, the conveyor belt of the cilia also comes to a standstill with increasing dryness. From this moment on, the body is almost defencelessly at the mercy of invading germs and pathogens!


Air coolers with a humidifying function are an effective protection against infection

With a constant air humidity between 40 to 60% RH you supply the body's own defence system with the necessary fuel, so that the important functions of the mucus membranes in the immune defence work optimally! In addition, optimal humidity kills infectious viruses in the room air. Trotec has the right air cooler with a humidifying function for the most diverse room sizes, applications and even for almost any personal taste.

The Trotec air cooler, combined with a BZ20M thermohygrometer, always helps you keep an eye on healthy room air humidity in a space with a relative humidity of 40 - 60% and ensure healthy room and breathing air!

Possible applications for our humidifiers

  • Healthy and virus-free breathing air in retirement and nursing homes

    A scratchy throat, itchy eyes, irritated mucous membranes, fatigue, chapped skin – all these are typical signs that something is not right with the ambient air. This is because the blame for this often lies in an overly dry room climate. These and additional symptoms increasingly occur during the heating season in particular – as do flu-like infections and colds, which are literally spread as...

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  • Humidification in daycare centres and schools

    Hardly anything affects our health as much as the air we breathe every day. This is particularly true for our children who attend schools and daycare facilities every day. Dry room air makes the little ones more susceptible to diseases and substantially lessens the power of concentration, consequently it is important to ensure the best hygienic conditions and fresh air for them. These institutions...

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  • Humidification in veneer warehouses

    Veneer is to be treated carefully. Especially in storage facilities with particularly dry air one needs to act prudently. In the process of drying veneer plywood begins to crack. In order to prevent costly desiccation damage the storage facility should be well equipped – with a reliable and efficient humidification system. The Trotec Group recommends the use of a humidifier for more extensive...

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  • Humidification in the instrument warehouse

    Premium timber, felt, glue and lacquer: Musical instruments are usually made of sensitive materials, which adds to their special sound and resonance. Hence, when storing these valuable instruments, it is particularly important to remember the optimum protection and care. This applies especially to musical instruments made in part or entirely of wood. For this material is constantly “working” (e.g....

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  • Humidification in greenhouses

    Warm temperatures and a high humidity level – those are the key factors required by tropical and subtropical plants, if you want them to grow and thrive. Mushroom farms also prefer warmth and moisture. Regular watering is not sufficient, for the majority of exotic plants absorbs moisture from the ambient air. Required for the generation of this special climate is not only a systematic heating...

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  • Humidification in server rooms

    Reliable technology is the most important criterion for customers connected to a computer centre. At the core of a firm stands its own server room, so to say, hence the technical equipment there ought to run smoothly at all times. The IT equipment must be in immaculate condition. With this in mind, the climate in data processing centres and server rooms must be geared to the technology's needs....

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