LONDON — Prime Minister Boris Johnson is being asked to answer one of the most devilish questions of the pandemic: What's the difference between two meters and one meter of social distancing, for public health and for saving the economy?

Or, asked another way, how much does it matter if restaurant diners or pub crawlers are required to be separated by six feet vs. three feet, more or less, with one meter being equal to 3.28084 feet?

Since Johnson ordered the United Kingdom into lockdown in March, Brits have been instructed — over and over — to please keep two meters of social distance between themselves to slow the spread of the coronavirus, which has killed at least 42,731 people here so far, the highest death toll in Europe.

But Johnson earlier this month ordered a government review of the distancing rules and is widely expected this week to endorse a new “one-meter-plus” fudge.

A policy shift is possible now, Johnson’s ministers say, because virus transmission is under control in Britain, with infections, hospitalizations and deaths falling. The prime minister appears prepared to signal an end to the national lockdown and announce that hotels, restaurants and pubs in England can reopen — with precautions — in early July. Leaders in Scotland, Wales and Northern Ireland are considering a similar relaxation of restrictions.

The overhaul of the distancing rule is also happening under intense political pressure and amid deep economic fear, from the board rooms to the factory floors.

The two-meter rule, say its many critics, is a job-destroyer based not on solid science but on averages and estimates of how far a cough, a sneeze or a laugh might launch droplets containing the virus, and how infectious those plumes may be.

In its embrace of a tough two-meter standard, Britain has been something of an outlier, alongside Spain and Canada.

Johnson’s government has been condemned for going into lockdown late, for failing to provide protective gear to front-line medical workers and for allowing the virus to sweep through its nursing homes. But on social distancing rules, the United Kingdom has been more cautious than most.

The World Health Organization recommends a distance of “at least one meter.” China, France, Denmark and Hong Kong went with one meter. South Korea opted for 1.4 meters; Germany, Italy and Australia for 1.5 meters.

In the United States, the Centers for Disease Control and Prevention recommended “at least six feet,” or 1.8 meters, “about two arms’ length” separation between people — though different states endorsed different measures at different times.

In Britain, the push to shorten the distance is coming in part from businesses, which are begging for relief after three months of lockdown.

Two meters of distance is not sustainable for many pubs, where customers traditionally jostle shoulder-to-shoulder to get their orders in.

UKHospitality, a trade body, warned that the sector’s revenue would be reduced by more than two-thirds if restaurants and pubs were forced to follow the current two-meter rule when they resume business in July.

The British Beer and Pub Association, a trade group, estimates that if distancing remains at two meters, only a third of pubs in England would be able to reopen. Cut the distance to one meter, and three-quarters of pubs might survive.

Michael Belben, owner of The Eagle gastropub in London, told The Washington Post he furloughed 19 bartenders and chefs in March as the government ordered workers home to wait out the pandemic.

“What they don’t understand is the difference between one meter and two meters. It comes down to how many people can be inside,” Belben said. “I can’t afford to lose money hand over fist.”

Richard Caring, a high-end restaurateur who runs the Annabel’s Club and The Ivy chain, told the Mail on Sunday that the government’s two-meter rule was “killing the country.”

It’s not just publicans and posh club owners calling for halving the required social distance. Top Tories in Johnson’s own Conservative Party have been pushing him to close the space gap — as have economists who are watching millions of jobs being lost as Britain falls into its deepest recession since the Great Frost of 1709.

Conservative lawmaker John Redwood said in Parliament last week, “Given that the scientific advice is mixed and muddled, and given that the economic and business advice is overwhelming and clear, why don’t ministers today announce the halving of the distance, ask business to put in other measures, including protective clothing and screens where appropriate?”

The science over the right number of meters is far from settled.

An ambitious review, published this month in the British medical journal the Lancet, of 172 observational studies across 16 countries and six continents concluded that “transmission of viruses was lower with physical distancing of one meter or more.”

The British government’s scientific advisers have offered their own pros and cons, stressing that risks are relative — that overall, yes, two meters was probably safer, but how much safer and at what cost?

Shaun Fitzgerald, an engineering expert at Cambridge University who helped inform the original two-meter rule, told the London Times, “The thing which is missing from a simple two-meter rule is consideration of other factors, such as time, duration and orientation.”

“It’s all three that are important,” he said. “I would not want to be one meter apart from somebody for an extended period because that’s much, much higher risk than two meters.”

Calum Semple, a professor of outbreak medicine at the University of Liverpool and a member of the government’s scientific advisory group, told BBC Radio, “The reason that I change my mind now, and whereas I was of a very different opinion three weeks ago, is that now we are in a position where there are low levels and sustained low levels of transmission throughout the country.”

“I’m still saying two meters is safer than one, but, in my opinion, it is now a reasonable political decision to relax these rules, perhaps accelerate school opening and start opening up other parts of the economy,” Semple said.

Scientific advisers, in a series of technical memos for the government, suggest that if the two-meter rule is changed, Britons should be wearing face coverings in public and spending less time in close indoor spaces with strangers.

At the beginning of the pandemic, Johnson and his top science advisers discounted the need for wearing masks. This month, they started requiring them on public transportation. They appear ready to once again adjust their positions.

Christine Spolar contributed to this report.