Cross-infection forms an additional danger for premature children with a poorly developed immune system. Therefore the air supply should contain fewer bacteries than room air. In industrial incubators this is achieved through a bacterial filter at the air inlet of the suction motor. The heated air is almost always re-used in this type of incubator. Because the Van Hemel Incubators do not have a motor no bacterial filter is applied, but the air is not re-used either. Huysman-Evers has tested the Van Hemel Incubator in the dispersion laboratory with three species of bacteries (staphylococcus aureus, pseudomonas, sarcinella). A very well-known professional incubator was installed for verification purposes. The growth of colonies in the Petri dishes put in the Van Hemel Incubator turned out to be significantly lower than in the professional one. This is probably the result of not recycling the air, short pasteurization, dehumidification and the subsequent humidification of the air.

Note: in professional incubators the newborn is continuously exposed to sound of the electromotor. The Van Hemel incubator does not use a motor.