Spending a few seconds one metre from a colleague is equivalent to an hour two metres away, and talking loudly makes it worse, experts warn.
Government scientific advisors are considering telling workers exactly how strong the risk of catching the coronavirus is depending on how close they stand next to someone.
The fresh advice would help employees ‘manage’ their risk of the killer infection where social distancing is difficult.
Companies are wrestling with new safety rules to allow employees to return to work as Prime Minister Boris Johnson sets out steps to restart the economy.
Social distancing is paramount, but there are growing concerns this won’t be possible for some employees in confined spaces, including construction site workers.
Pictured, construction workers in south London on May 12. People in manual jobs may find it harder to social distance at work
Ministers are hoping for a gradual re-opening of schools from June 1, but there are fears children will be unable to properly social distance.
It follows a study last week that showed talking loudly for just one minute can produce a high load of viral particles that stay in the air for eight minutes.
Other simulations show how far infected particles from a cough or sneeze can travel in confined spaces.
Employers in the UK have been told to re-design workspaces to ensure workers are at a two metre distance from others as much as possible.
The new ‘COVID-19 secure’ guidance covers eight workplace settings which are allowed to be open, including construction sites, factories and takeaways.
Where social distancing is difficult, there should be barriers in shared spaces, staggered start times and one-way walking systems, the guidance says.
But where social distancing is seemingly impossible, a sub-group of the Scientific Advisory Group for Emergencies (SAGE) is examining how workers can ‘manage’ the risk, the Sunday Telegraph reports.
Andrew Curran, chief scientific adviser at the Health and Safety Executive said being exposed to someone for ‘a few seconds’ at a one metre distance could equate to around an hour of being two metres away from the same person.
He said: ‘If the exposure at a distance of less than two metres is going to be for a short period of time, you manage the risk in the context of duration and orientation.
‘There is some physics in this and the Sage sub-group is looking at that to provide better information.
‘For example, if you were exposed for a few seconds at one metre, that is about the same as being exposed for a longer period of time – an hour, say – at two metres. It is that order of magnitude.
‘There may be elements within a job where there is exposure for a short period, but where the risk is so low it can be managed.’
Two metres is considered a safe distance by health chiefs because the coronavirus predominantly spreads in respiratory droplets in a sneeze or cough.
These large droplets fall to the floor due to gravity within a short distance, around one metre, from the person who expelled them. The ‘safe’ distance is double that in order to optimise protection.
Two metres is not a ‘magical number’ according to John Simpson, a medical director at Public Health England.
He said ‘there is a duration and distance element to exposure that has to be worked through’, as scientists continue to work out how the coronavirus spreads in different conditions.