FFP3 (filtering face piece 3) respiratory masks, known in the U.S. as N99, can reduce transmission of COVID-19 by up to 100 percent, according to a study conducted on hospital wards

The data, which were collected in 2020 and have not yet been peer-reviewed, indicated there was a significantly larger chance of hospital staff wearing standard-issue surgical masks catching the virus. 

The study by the Cambridge University Hospital NHS Foundation Trust prompted calls for hospital workers in the UK to be issued with the higher standard face covering.

National Guidance currently recommends that healthcare professionals should wear surgical masks, with the exception of a few limited situations. 

However, the study found that staff caring for patients on red wards (those with patients who had tested positive for COVID-19) were exposed to a risk of contracting the coronavirus that was up to 47 times higher than those on green or non-COVID-19 wards.

WATCH: Face masks: Which one, when and why?

When infections were rising rapidly again in December 2020, the protection on wards at the hospital in Cambridge was upgraded to FFP3 masks. In the weeks that followed, the study found the rate of infections among healthcare professionals working on red wards fell to levels experienced by staff on green wards where there were no COVID-19 patients. 

The study states: "Cases attributed to ward-based exposure fell significantly, with FFP3 respirators providing 31-100 percent protection (and most likely 100 percent protection) against infection from patients with COVID-19."

READ MORE

Spain ditches face masks rule

Face masks: How they vary, what they cost

Indonesia's fast fashion pollution problems

Fluid-resistant masks were also described as being "insufficient" to protect healthcare workers and any remaining cases on the red ward with the upgraded masks were considered to have been spread in the community as opposed to in the hospital. 

Michael Weekes from the Department of Medicine at the University of Cambridge says the data suggest there's "an urgent need to look at the PPE offered to healthcare workers on the front line." 

"Upgrading the equipment so that FFP3 masks are offered to all healthcare workers caring for patients with COVID-19 could reduce the number of infections, keep more hospital staff safe and remove some of the burden on already stretched healthcare services caused by absence of key staff due to illness. Vaccination is clearly also an absolute priority for anyone who hasn't yet taken up their offer."

The Cambridge trust is one of 17 institutions across the UK that has decided to upgrade PPE regardless of national policy. 

WATCH: The case for clear face masks, visors and shields