Reducing viral load
As the COVID 19 patients fill capacity in the ICU and HDU facilities of all NHS hospitals, the next course of action is to convert standard wards or even non-hospital buildings (e.g. Operation Nightingale at London’s Excel) into makeshift emergency facilities.
ICU wards are built to a certain standard. Air quality is maintained by changing the room air circa ten times per hour via a filtered supply. Theatre air is a higher grade, recycled circa twenty-five times per hour via an H8 filter.
The idea is to reduce the viral load to <1% which QA has deemed through study, keeps the front-line staff and the patient in a safe environment.
The temporary facilities generally do not have this level of built in filtration, hence viral load will increase as air change rate and filter quality reduces, putting staff at risk. Losing qualified front line staff resource is short term irreplaceable and can be prevented.
View academic paper “The ventilation of multiple-bed hospital wards: Review and analysis“
HEPA filters have been around for generations, are proven technology in trapping pathogens and are relatively inexpensive. A portable HEPA on a frame with pre-filter can move 1100m3 of air per hour and trap 99.995% of particulate above 0.3micron. COVID 19 apparently is prevalent in droplets of circa 1 – 5 micron so within the HEPAs design envelope.
A single mobile HEPA station would convert standard hospital ward floor space of 30m2 x 3.5m ceiling height to at least ICU air standards (10 air changes per hour). These units are easy to build and quick to deploy. They just need a standard UK 3 pin mains socket.