Properly functioning ventilation is indispensable in any indoor space where people spend time. The air flowing in from outside ensures the exchange of expended and polluted air for the fresh air which is essential to our breathing.

The exchange of air is essential for two reasons. The first is that all the polluted air needs to be removed from the space. The second is particularly crucial in terms of hygiene; the necessity of counteracting the unacceptably intense heating and humidification of the air brought about by the emission of water vapour and heat by the people occupying the space.

Generally speaking, in spaces designed for the presence of people, natural ventilation provides protection against water vapour condensing into drops on the structural surfaces and the damp and fungi that can then ensue. However, simply employing an exchange of air as a solution is by no means always sufficient. Which is why additional treatment in the form of cooling and dehumidifying is essential during the hot season.

In many cases, besides this fundamental function, ventilation must also fulfil a second task. In a given room, it must generate either positive or negative pressure in relation to the pressure in the neighbouring rooms or outside in order to prevent undesirable air currents from occurring inside the building.

Any space where halotherapy is provided requires proper ventilation. The ventilation should accord with the direction of the flow of the air rich in the dry salt aerosol produced by the halogenerator. The minimum requirement for the intake of fresh air is between 20 and 30 m3 per hour for each person in the space.

The physical properties of salt make it imperative to maintain the ambient humidity at a level which does not exceed 60%. In conditions of a higher humidity, salt becomes hygroscopic. This makes it impossible to grind effectively in a halogenerator. No matter where the halotherapy is offered, ventilation is crucial to its efficacy.

The use of ventilators causes variations in temperature, as does the impact of the wind. This gives rise to air currents and they, in turn, trigger the exchange of air. The choice of ventilation method, the degree to which the air being blown in is treated and the volume of air to be exchanged all depend on the purpose of the space in question.

When evaluating a ventilation design, attention should be paid to obtaining a solution whereby the most favourable air conditions, without the occurrence of draughts, prevail in the area of the space designed to accommodate people. The per-unit air requirement per person depends on the kind of activity carried out in a given space.

Whether or not it is possible to meet physiological and thermal needs on the basis of the per-unit air requirement depends on the surface area of the floor and the volume of space we assign per person, as well as on the thermal conditions of the air outside. In some cases, the use of air-cooling and dehumidifying devices will be essential.

Gravity air vent ducts do not always provide assured and uniform ventilation. This is caused by external conditions and faulty workmanship. When properly made and installed, however, they can provide an exchange of air. The functioning of gravity air vents is contingent on external factors. The action of extraction ducts installed at the highest point of the roof of a building depends on exploiting the differences in the inside and outside air temperatures.

The forces which set air in motion, even at low outside temperatures, are negligible and can even be negative in the summer. The functioning of extraction ducts can be considerably reinforced by the impact of the wind and can sometimes also be enhanced thanks to the use of a ventilation cap.

When designing and constructing the ducts, attention should be paid to specific aspects of their construction. The extraction aperture should be as large as is possible; the closure needs to be excellent; the duct walls must be carefully built; and there needs to be a sufficiently large aperture for the inlet air.

Air is also extracted from a room and expelled outside it by means of mechanically driven extraction ventilators located in the walls or windows. Another method of ventilation is the use of ventilators which impel air into a room; the air inside it is then pushed outside.

Ventilation devices make it possible to maintain a constant, specified exchange of air. Because they regulate the initial warming of the inlet air, it is possible to air a space in the cold season without worrying that draughts will occur.

The purity of the inlet air is also a crucial issue. If the outside air is polluted, then the additional use of filters will be essential. The inlet air should not contain more than 0.5 milligrams of dust per cubic metre.

Halotherapy is the breathing of pure air enriched with salt aerosol.