Doctors and nurses are being put at risk of catching Covid-19 because hospitals are abandoning vital checks to ensure their personal protective equipment (PPE) fits properly.

Growing numbers of hospitals are running so short of FFP3 face masks they are no longer insisting staff have a “fit-test” before they start wearing a mask while treating infected patients.

NHS trusts do not want to deplete their limited supplies of the disposable masks by using them up during what until now have been seen as routine and necessary checks to ensure the virus cannot get past the mask and into the wearer’s nose or mouth.

The fit-test is a rigorous process which ensures health workers wear the right size mask, which does not leak. The masks are sprayed with a chemical mist to see if staff can taste it.

However, trusts are instead telling staff to carry out what doctors fear is a crude and unreliable manual assessment, known as a “fit-check”, to see if masks have any gaps. This involves checking the seal by covering the filter, breathing in and seeing if the mask sucks in.

The Doctors’ Association UK (DAUK) says that hospitals which no longer do fit-tests are playing “Russian roulette with doctors’ lives” at a time when Covid-19 has already claimed the lives of at least 40 NHS doctors, nurses, paramedics, midwives and porters.

Hospitals appear to be in breach of Health and Safety Executive guidelines, which specify that anyone using a disposable respirator such as an FFP3 in the course of their work should always have a fit-test first.

For example, Northwick Park hospital in London emailed its staff last week to tell them: “As you know, there is currently an international shortage of FFP3 masks. That means we can’t rely on receiving the same types of mask that have been used in the fit testing process. Instead we are needing to change masks as supplies come into place.

“Therefore, we are adopting an approach that has already been put in place in a number of trusts both in London and nationally: we are training staff to properly identify and use the best fitting FFP3 mask presently available, and to check that they have a good seal.

“This is designed to keep you as safe as possible, regardless of which masks we have in stock.”

Hospitals are also ditching fit-tests because they have been unable to get hold of the chemicals involved.

Samantha Batt-Rawden, DAUK’s president and an intensive care specialist, said: “This is a scandal which shows a flagrant disregard for the safety of frontline NHS staff. Many doctors will ‘fail’ a fit-test on certain brands of mask, which means it will not work for them.

“With mask brands and types regularly changing due to shortages, sometimes shift to shift, doctors are now going in blind, with no way of knowing whether a particular mask will give them any protection whatsover. It is simply unacceptable to play Russian roulette with doctors’ lives.

“This flagrant disregard for the safety of dedicated NHS staff must be addressed as a matter of urgency.”

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One hospital consultant said: “I’m worried. I tried to get fit-tested and my hospital isn’t testing anyone now. I’ve just been told to breathe deeply and see if there is a leak. How is this safe? They won’t admit it but they are gambling with our lives because they don’t have enough masks.”

Prof Neil Mortensen, the president-elect of the Royal College of Surgeons of England, said: “Respiratory protective equipment needs to fit the wearer’s face and must be tested before it is used to ensure it is effective. Surgeons who responded to our survey said they have been told to ‘fit-test themselves’, highlighted mask shortages, and mentioned shortages of the testing solution.”

Chris Hopson, the chief executive of NHS Providers, which represents NHS trusts in England, said the NHS had a “plentiful” supply of FFP3 masks but that there were “several challenges around fit-testing”.

He said: “The current emergency PPE distribution system, which proactively delivers PPE to trusts without them having to order it, means trusts are receiving up to five different brands of face mask. Each time a person starts using a different brand of mask, they need a new fit-test. This can take up to an hour for each member of staff.

“There has also been a shortage of fit-testing solution, though we understand this is now easing. Trust leaders will always do everything they can to ensure every member of staff is appropriately fit-tested.”

An NHS spokesperson said: “National guidance is clear that fit-tests are required in hospitals. Government is continuing to procure vital protective equipment in line with its PPE strategy, and over the bank holiday weekend more than 48m pieces of protective kit were distributed to us, including 160,000 fit-test solutions and 8,000 fit-test kits.”

• This article was amended on 15 April 2020. A reference to Derriford hospital having suspended mask fit-testing was removed after University Hospitals Plymouth NHS Trust informed the Guardian that testing had not been stopped.