Indoors: a bundle of measures against the spread of viruses

Wind is the most effective enemy of viruses and therefore the best tip against the transmission of diseases is: “Get outside, get some fresh air!” Unfortunately, this is not really helpful for companies with offices and production that takes place under roofs and in halls.

Good news: viruses and aerosols are not defenceless in buildings. They love rooms where there is a lot of loud talking. But they hate wind and fresh air. Ventilation as much as possible is therefore the order of the day. Applied to workplaces, workbenches, desks and production lines, the consequence is to provide as much fresh air as possible.

The following measures are necessary to combat the spread of aerosols and viruses indoors:

Natural ventilation:

Ventilate as often as possible by opening windows. The exchange of air provides fresh outside air and dilutes the room air, reducing the concentration of aerosols and viruses. Shock ventilation with windows open as wide as possible is more effective than permanent tilting. This ensures better air exchange than simply tilting the windows. In addition, regular shock ventilation is more energy-efficient than constant, “half-hearted” ventilation.

Ventilate with ventilation systems:

If natural ventilation is not possible or practical, or if heat escapes unused in the cold season, a modern ventilation system is essential. It ensures automatic air exchange indoors and in the hall. With a modern and efficient ventilation system, the air quality can be significantly improved and the proportion of aerosols and viruses significantly reduced.

Correct ventilation with ventilation and air conditioning systems:

Virologists and ventilation engineers now assume that a risk of infection indoors is reduced by ventilation and air conditioning systems. A constant supply of fresh air significantly reduces the risk of infection. The protective effect of ventilation and air conditioning systems against aerosols and viruses is largely dependent on the following issues:

1. complete air exchange
2. correct air flow
3. maximum air volume
4. highly separating filter elements
5. ongoing inspection and maintenance incl. hygiene inspection
6. modern measurement technology

Firstly, the supply of fresh outside air is crucial for optimum protection against viruses and aerosols from ventilation systems: instead of recirculating purified air. Ventilation systems should therefore be operated in exhaust air mode. In the case of recirculated air operation, highly separating filter elements must be used. This minimizes the risk of a possible concentration of viruses and aerosols due to leaks and when using filter inserts with a low filtration effect.

Secondly, the correct air flow in the room and in the hall is crucial: ideally, the air indoors is renewed by diffusion in the floor area without turbulence. The resulting air stratification in the room or hall ensures that the room air is largely completely renewed. The fresh air does not mix with the existing room air. This prevents aerosols and viruses from being transported to other areas.

Thirdly, the high air volume is crucial: with conventional air exchange rates in residential and office buildings, the pathogens - via aerosols - can often remain in the room for hours. This is the sober result of a recent study by the Technical University of Berlin. This is all the more true if there is an infectious person in the room: in the case of an asymptomatic infection, this person “supplies” the aerosols in the air with viruses almost continuously. For optimum protection against viruses and aerosols, the amount of air should therefore be maximized. More fresh air inside and in halls offers optimum protection.

Fourthly, highly separating filter elements should be used: they ensure the highest air quality of the fresh air introduced (or recirculated air in the case of recirculation operation) - free of ultra-fine particles, aerosols and viruses. After all, air pollutants in turn promote the spread of viruses.

Fifthly, ventilation systems must be regularly maintained and inspected by experts: ideally, a hygiene inspection should be carried out with a hygiene inspection of the entire ventilation and air conditioning system in accordance with VDI 6022.

Sixthly, the use of modern measurement technology to automate the ventilation system makes sense: aerosol experts consider measuring devices for assessing air quality to be helpful. Ideally, these are networked with the existing ventilation systems and thus regulate their use automatically.

Organizational measures

Since life and production must and should continue nevertheless - additional attention must be paid when people are in closed rooms:

• Control of use in neuralgic places: the smaller rooms are and the more people are in them at the same time, the greater the risk of infection. This applies in particular to break rooms, checkrooms, lounges, elevators, etc. Measures to control the length of stay and use of such rooms may be annoying, but they are essential for health.
• Behavior: loud talking, shouting and screaming enriches the indoor air with particles. This also applies to strenuous activities and the associated increase in breathing frequency during production.