The Royal College of Emergency Medicine (RCEM) estimated 36 Scots died as a direct result of avoidable delays in the week to March 30.
It comes as the number of people in hospital with Covid reached another record high, the worst cancer waiting times were reported since records began in 2006, and the Royal College of Nursing issued a warning that patient care is under “serious threat” from record-high staffing shortages.
The RCEM said it would “welcome” a decision to extend the legal requirement to wear face coverings in Scotland to protect the NHS.
Nicola Sturgeon is set to update MSPs on whether the rule will be scrapped as planned from Monday.
“Anything that can continue to reduce the spread and therefore try and relieve as much pressure as possible in the healthcare system would be welcomed,” said RCEM Vice President in Scotland Dr John Thomson.
Heath Secretary Humza Yousaf told MSPs on Tuesday that "ultimately the single most important factor in easing A&E pressure is controlling Covid transmission".
Just 66 per cent of people visiting A&E in the week to March 20 were admitted, transferred or discharged within the government target of four hours, according to Public Health Scotland.
This is the lowest figure since records began in February 2015, while the highest number of people ever waited over four, eight and 12 hours.
Some 1,015 people waited over 12 hours, the first time the figure has reached above 1,000, and a 34 per cent increase on the next-highest figure, recorded the previous week.
Last week also saw the worst performance ever for a single hospital, as the Queen Elizabeth University Hospital (QEUH) in Glasgow achieved the four hour target in just 40 per cent of cases.
Edinburgh’s Royal Infirmary (ERI) recorded the third-worst performance, at 42 per cent. Some 284 people waited over 12 hours at the ERI, while 86 waited that long at the QEUH.
Dr Thomson, who is also an emergency medicine consultant at Aberdeen Royal Infirmary, said the government must understand the “unconscionable” harm coming to patients.
“We have clear evidence that prolonged weeks in an emergency department lead directly to patient deaths,” he said.
“Good evidence that, irrespective of what the medical problem is that they present with, that long wait alone is associated with death.
“We can measure that quite clearly. One in 72 patients who wait in an emergency department beyond eight hours will die as a direct result.
“In the last week alone we would estimate there were 36 avoidable deaths due to waits beyond eight hours. That's unconscionable.”
A&E’s in Scotland are facing the “biggest patient safety crisis for a generation”, he said.
"The workforce is decimated, with a degree of Covid but also significant absences due to burnout,” he said.
“People are working in an environment in emergency departments that they shouldn’t.
“We’re always crowded. We have patients waiting many hours, if not days. We have ambulances queued up outside with patients breaching the four hour standard before they even leave the ambulance to get into the department.
“You can imagine the demoralising moral injury on staff. We are trying to provide the best quality care in very difficult circumstances, and we are really unable to do so.”
Covid is not the sole reason for pressure on A&E departments, he said, but it is a factor, and the college would welcome a decision to extend face covering rules.
“Given the current infection rates... then if that was the decision we would support that in terms of a necessary measure to try and reduce the spread of Covid,” he said.
“Ultimately, that impacts on us, either in terms of patients we're seeing within emergency departments or the capacity available within hospitals.”
Scottish health spokesperson Dr Sandesh Gulhane labelled the most recent A&E figures “atrocious” and they ought to “shame” the government.
Liberal democrat leader Alex Cole-Hamilton said the health secretary and First Minister have “lost control” of the situation.
Scottish Labour said the government is “risking lives” with continued delays.
In response to the figures, Health Secretary Humza Yousaf said: “The unprecedented impact of the pandemic is continuing to take its toll on our NHS and these latest figures continue to underline the extent of the pressure on services.
"We are currently seeing record high levels of Covid transmission and more people in our hospitals with Covid than at any time during the pandemic and this rise in recent weeks has inevitably had an impact on services like A&E.”