Temperature and relative humidity affect the airborne survival of viruses, bacteria and fungi. Environmental control in hospitals is not only valuable for human comfort and energy saving but important because of infectious disease transmission from aerosols or airborne infection. Maintaining hospital premises at a certain temperature and a certain relative humidity (40 to 60 %rh), is likely to reduce the airborne survival and therefore transmission of influenza and other viruses or bacteria.
Another source for the spread of bacteria is drinking water. The development of legionella in drinking water lines can be prevented by avoiding a temperature range of 25 °C to 55 °C and with regular “thermal disinfection” by heating tanks and pipe system to above 70 °C.