Humidity and COVID-19 in data centers

Data center managers have gone to some lengths to avoid transmission of the COVID-19 virus in their facilities. Fortunately, many factors help keep transmission rates low in data centers: few staff are required; most jobs do not require close physical interaction with colleagues; and air filtration may help to reduce, if not necessarily eliminate, airborne transmission.

Presently, researchers are still debating the extent to which the virus can be transmitted through the air. Early in July, over 200 scientists wrote the World Health Organization (WHO), asking it to officially acknowledge that coronavirus transmission could be airborne. (Airborne transmission requires tiny particles containing infectious microorganisms stay suspended in the air for long periods of time. This is distinct from droplet transmission, which requires relatively close proximity and shorter time frames.) If this is the case, it means maintaining a 2-meter (approximately 6-foot) distance from others may be a less effective means of preventing transmission, especially indoors, than previously thought.

If a virus is transmitted in this way, the level of humidity can play a significant role in increasing or decreasing infection rates. Uptime Institute’s advisory report Pandemic planning and response: A guide for critical infrastructure addresses humidity and air filtration, but primarily in terms of ensuring appropriate air temperature and humidity for effective operation, especially if additional filtration is used.

Research suggests that not only does low humidity help particles stay aloft longer, but also dry air decreases the effectiveness of the initial human response to a viral infection. Cold, dry air brought in from outside, then warmed, may be a particular concern, because the humidity drops significantly.

At the same time, higher levels of humidity increase condensation, even if not perceptibly. This enables the virus to remain infectious on surfaces for a longer period of time.

As it turns out, humidity may not be such a concern for data centers — although it may be an issue for offices and other indoor spaces. The ideal level of humidity to minimize airborne transmission of a virus may be in the region of 40% to 60%. Fortunately, this a perfect match for data centers: ASHRAE’s 2016 guidelines recommend data centers maintain ambient relative humidity of 50% (previously 45% to 55%). Data centers operators should, however, review the ideal humidity for non-white space areas.