Healthy air humidity (Part 1)

This technical paper from Nortec looks at the importance of air humidification in hospitals and in outpatient settings. Part 1 of this article focuses on the necessity of humidification in hospitals.

Part 2 - There might be a serial-killer in our hospitals!
Part 3 - Healthy air humidity

The necessity of humidification in hospitals

People are admitted to hospitals when a serious health disorder occurs. It is therefore essential that patients encounter an environment that is optimally suited to enhance their recovery.

For every emergency, medical treatment, operation, intensive care or rehabilitation measure, the ambient conditions in a hospital have to support healing. Indoor conditions must not be allowed to stand in the way of a full recovery, nor lead to other patients contracting new infections. The quality of the ambient air contributes significantly to patient outcomes.

Outdoors, the risks of infection from contact with viral or bacterial pathogens are extremely low since microbes are quickly diluted in the vast amount of air. Not so in closed spaces!

Optimal air humidity for humans 40 60 RHOptimal air humidity for humans 40–60% RH.

Indoors, we are faced with a limited volume of air supply, which we share among each other for our breathing needs. In hospitals, an increased risk of what is known as a nosocomial infection exists in many areas; that is, a disease originating in a hospital. These infections are commonly referred to as HAIs, or hospital acquired infections.

To keep this risk of infection low, the ambient air has to be treated. It has to be conditioned in such a way that, in practical terms, pathogens have no chance of survival. Achieving optimal indoor conditions requires the implementation of both the desired temperature along with a relative humidity level of between 40 and 60%. Therefore, external air that is sucked in must be humidified or dehumidified in a central air-conditioning system regardless of the time of year. Particular attention must be paid to dry ambient air, as it favours the survival of viruses and bacteria, and they weaken our immune systems, attack the mucous membranes, and leave us with dry skin and eyes.

What is crucial for achieving optimally conditioned ambient conditions, what needs to be kept in mind, and what solutions are available? This article provides information on these topics and on healthy air humidity and its significance in hospitals and medical facilities. 

Healthy air humidity is significant in hospitals and medical facilitiesMMHealthy air humidity is significant in hospitals and medical facilities.

Hygiene

The aim of hygiene is to maintain or improve the operational capacity and well-being of individuals and society. A main focus is on the prevention of infectious diseases. In this regard, hygiene is setting new challenges on a continuous basis as bacteria become more and more resistant.

Hospital hygiene is concerned with the research, prevention and defence against infectious diseases, which are acquired in hospitals, clinics or similar facilities. Thus, it equally serves for the protection of patients and staff and therefore overlaps with occupational health and safety.

The prevention of nosocomial infections in hospitals, is therefore a focal point in hospital hygiene.

In operating theatres and clean rooms in particular, isolation stations, intensive care and delivery rooms, a hygienically flawless ambient air supply is vital.

In operating theatres and clean rooms in particular, isolation stations, intensive care and delivery rooms, a hygienically flawless ambient air supply is vital.

This is because, when the body’s defences are weakened, the immune system is particularly susceptible to disease-causing agents. Through the skin and essential breathing, the patient comes in direct contact with the ambient air. Its hygiene is therefore of utmost importance for the maintenance, promotion and fortification of a patient’s health.

Therefore, a mechanical air supply must be provided at all times by means of an HVAC system; thus, external air must be heated, cooled, filtered, and humidified or dehumidified and the supply air must be monitored at all times before entry.

When the bodys defences are weakened the immune system is particularly susceptible to disease causing agentsMMWhen the body’s defences are weakened, the immune system is particularly susceptible to disease-causing agents.

Danger of germs through aerosols

Water aerosols like droplets of mist or steam are tiny particles that are capable of floating. Their size determines how many microorganisms they can carry. They get into our bodies via the airways; in this regard, we know the interrelationship of size and depth of penetration into our organism.

Inhalable (0.5—18.5μm)

  • Nose and throat area: 10—5μm
  • Trachea: 5–3μm

Thoracic aerosols that penetrate through the larynx right into the bronchi

  • Bronchi: 3–2μm
  • Bronchioles: 2–1μm

Alveolar duct aerosols that penetrate into the pulmonary alveoli

  • Alveoli: 1–0.1μm

When coughing and sneezing, disease-causing agents such as flu viruses can be literally shot into a room through such droplets via saliva or mucous at speeds of up to 20m/s and transferred to other people through inhalation. The ambient air humidity plays a decisive role in the capacity to survive and the floating behaviour of the tiniest aerosol particles of these pathogens. But what exactly is the reason for this?

When coughing and sneezing disease causing agents such as flu viruses can be literally shot into a roomMMWhen coughing and sneezing, disease-causing agents such as flu viruses can be literally shot into a room.

Germs love dry air

Dry ambient air with a relative humidity of under 20% allows tiny droplets that are loaded with flu or cold viruses to dry up. They then shrink to sizes of up to 0.5μm.

At the same time, their salt concentration increases so much that a veritable crust forms around them in the dry atmosphere. Thus, the capacity of the germs to survive indoors and the ability of the droplets to float are maximised. They can survive for up to 41 hours. So, if anyone who has a cold coughs into a room that is too dry, this generates a contaminated atmosphere that can last for nearly two days.

The result is a high probability of other people present or people who enter the room breathing in these particles. Then it depends solely on their body’s own defences and on the functioning of their immune system whether or not an infection occurs.

Moist air kills viruses

A constant relative air humidity between 40 and 60%, prevents droplets from drying out and forming a salt casing. Viruses and germs are thus deprived of the basis for their survival; in a highly-concentrated saline solution they become inactive within a few minutes.

In addition, droplets with diameters of up to 100μm remain comparatively large. Their ability to float is thus severely limited. They slowly sink to the floor and can then no longer be inhaled. The size also prevents them from penetrating our organism.

<insert image on p6 of pdf>
<caption> Float duration in the air.

*To be continued | Republished with permission.


 

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