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Covid-19: Sense and Nonsense to Filters Ventilation Systems


We have received many questions about COVID-19 in connection with air conditioning and ventilation systems. In some cases, there is still no reliable knowledge.

The following answers and recommendations are based on the current state of knowledge.


1. Can the virus be transmitted by air through HVAC systems (air conditioning systems)?

» According to current knowledge, transmission occurs mainly through relatively large droplets (> 5 micrometers – one millionth of a meter), for example when speaking, especially when coughing or sneezing.

The transmission over the air can then take place over a short distance of approx. 1.5 meters – from this the recommendation is derived to maintain a safety distance of 2 meters as a preventive measure.

The droplets settle quickly due to gravity and contaminate surfaces in this way.

The few measurements available to date allow the conclusion that the risk posed by airborne viruses can be assessed as low. So far, no infection has been detected by an HVAC system, neither in SARS nor in the case of COVID-19.

Experts consider the transmission via HVAC systems to be very unlikely.


2. Are there filter that filter out Covid-19 Virus?

» Yes. There are

HEPA filters are particularly suitable for separating viruses and bacteria. For example, an H13 filter has a separation efficiency of 99.95% in the minimum separation efficiency (approx. 0.2 µm). However, these filters are typically only used for sensitive areas such as clean rooms and operating theaters in hospitals.

The installation of such filters in a ventilation system for, for example, office areas means a high pressure loss, resulting in increasing in energy costs.

Since the transmission of corona viruses via air-conditioning systems can almost be ruled out, using these special filters is not necessary.



Tìm hiểu bộ lọc HEPA trong máy hút bụi

HEPA Filters


3. Are There Any Special Recommendations for Room Ventilation Systems? 

There is something we need to do. For example:

» Do not turn off ventilation and air conditioning systems.

» Do not reduce outside air flow and air components circulation.

» Extend the operating time of the system before and after longer to normal. On the other hand, it is recommended to clean the air line regularly and replace the filter.