A new study has shown that the airborne transmission of the coronavirus is highly random and suggests that the two-metre rule was a number chosen from a risk "continuum", rather than any concrete measurement of safety.
A team of engineers from the University of Cambridge used computer modelling to show how droplets spread when people cough.
They found that without masks, a person with Covid-19 can infect another two metres away, even outdoors.
The team also found that coughs vary widely, and that the "safe" distance could have been set at anywhere between one and three metres, or even more, depending on the risk tolerance of the public health authority concerned.
The results, published in the journal Physics of Fluids, suggest that social distancing is not an effective measure on its own.
They emphasise the continued importance of vaccination, ventilation and masks as the northern hemisphere heads into winter.
Despite the focus on washing hands and cleaning surfaces in the early days of the pandemic, it has been clear for nearly two years that Covid-19 spreads through airborne transmission.
Infected people can spread the virus through coughing, speaking or even breathing, when they expel larger droplets that eventually settle or smaller aerosols that may float in the air.
Prof Epaminondas Mastorakos from the University of Cambridge’s department of engineering, who led the research, is an expert in fluid mechanics – the way that fluids, including those in exhaled breath, behave in different environments.
Over the course of the pandemic, he and his colleagues have developed various models for how Covid-19 spreads.
“One part of the way that this disease spreads is virology: how much virus you have in your body, how many viral particles you expel when you speak or cough,” said lead author Dr Shrey Trivedi, also from Cambridge's engineering department.
“But another part of it is fluid mechanics: what happens to the droplets once they’re expelled, which is where we come in.
"As fluid mechanics specialists, we’re like the bridge from virology of the emitter to the virology of the receiver and we can help with risk assessment."
In the current study, the researchers set out to "measure" this bridge through simulations.
For example, if a person coughed and emitted 1,000 droplets, how many would reach another person in the same room, and how large would these droplets be, as a function of time and space?
The simulations used refined computational models solving the equations for turbulent flow, together with detailed descriptions of droplet motion and evaporation.
The researchers found that there is not a sharp cut-off once the droplets spread beyond two metres.
When a person coughs and is not wearing a mask, most of the larger droplets will fall on nearby surfaces.
But smaller droplets, suspended in the air, can quickly and easily spread well beyond two metres. How far and how quickly these aerosols spread will depend on the quality of ventilation in the room.
In addition to the variables of ventilation and wearing masks, there is also a high degree of variability in individual coughs.
“Each time we cough we may emit a different amount of liquid, so if a person is infected with Covid-19, they could be emitting lots of virus particles or very few, and because of the turbulence they spread differently for every cough,” said Dr Trivedi.
Prof Mastorakos said: “Even if I expel the same number of droplets every time I cough, because the flow is turbulent, there are fluctuations.
“If I’m coughing, fluctuations in velocity, temperature and humidity mean that the amount someone gets at the two-metre mark can be very different each time."
The researchers say that while the two-metre rule is an effective and easy-to-remember message for the public, it isn’t a mark of safety, given the large number of variables associated with an airborne virus.
Vaccination, ventilation and masks, while not 100 per cent effective, are crucial for containing the virus.
“We’re all desperate to see the back of this pandemic, but we strongly recommend that people keep wearing masks in indoor spaces such as offices, classrooms and shops,” Prof Mastorakos said.
“There’s no good reason to expose yourself to this risk as long as the virus is with us.”
The research team is continuing this research with similar simulations for spaces such as lecture rooms as people spend more time indoors.
The specs
Engine: 2.2-litre, turbodiesel
Transmission: 6-speed auto
Power: 160hp
Torque: 385Nm
Price: Dh116,900
On sale: now
SERIE A FIXTURES
Saturday Benevento v Atalanta (2pm), Genoa v Bologna (5pm), AC Milan v Torino (7.45pm)
Sunday Roma v Inter Milan (3.30pm), Udinese v Napoli, Hellas Verona v Crotone, Parma v Lazio (2pm), Fiorentina v Cagliari (9pm), Juventus v Sassuolo (11.45pm)
Monday Spezia v Sampdoria (11.45pm)
Abu Dhabi traffic facts
Drivers in Abu Dhabi spend 10 per cent longer in congested conditions than they would on a free-flowing road
The highest volume of traffic on the roads is found between 7am and 8am on a Sunday.
Travelling before 7am on a Sunday could save up to four hours per year on a 30-minute commute.
The day was the least congestion in Abu Dhabi in 2019 was Tuesday, August 13.
The highest levels of traffic were found on Sunday, November 10.
Drivers in Abu Dhabi lost 41 hours spent in traffic jams in rush hour during 2019
Our family matters legal consultant
Name: Hassan Mohsen Elhais
Position: legal consultant with Al Rowaad Advocates and Legal Consultants.
Killing of Qassem Suleimani
UAE currency: the story behind the money in your pockets
EPL's youngest
- Ethan Nwaneri (Arsenal)
15 years, 181 days old
- Max Dowman (Arsenal)
15 years, 235 days old
- Jeremy Monga (Leicester)
15 years, 271 days old
- Harvey Elliott (Fulham)
16 years, 30 days old
- Matthew Briggs (Fulham)
16 years, 68 days old
Volvo ES90 Specs
Engine: Electric single motor (96kW), twin motor (106kW) and twin motor performance (106kW)
Power: 333hp, 449hp, 680hp
Torque: 480Nm, 670Nm, 870Nm
On sale: Later in 2025 or early 2026, depending on region
Price: Exact regional pricing TBA
Global state-owned investor ranking by size
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UAE
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Norway
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Canada
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england euro squad
Goalkeepers: Dean Henderson (Man Utd), Sam Johnstone (West Brom), Jordan Pickford (Everton)
Defenders: John Stones (Man City), Luke Shaw (Man Utd), Harry Maguire (Man Utd), Trent Alexander-Arnold (Liverpool), Kyle Walker (Man City), Tyrone Mings (Aston Villa), Reece James (Chelsea), Conor Coady (Wolves), Ben Chilwell (Chelsea), Kieran Trippier (Atletico Madrid)
Midfielders: Mason Mount (Chelsea), Declan Rice (West Ham), Jordan Henderson (Liverpool), Jude Bellingham (Borussia Dortmund), Kalvin Phillips (Leeds)
Forwards: Harry Kane (Tottenham), Marcus Rashford (Man Utd), Raheem Sterling (Man City), Dominic Calvert-Lewin (Everton), Phil Foden (Man City), Jack Grealish (Aston Villa), Jadon Sancho (Borussia Dortmund), Bukayo Saka (Arsenal)
The specs
Engine: 1.5-litre turbo
Power: 181hp
Torque: 230Nm
Transmission: 6-speed automatic
Starting price: Dh79,000
On sale: Now
Heather, the Totality
Matthew Weiner,
Canongate
THE%20SPECS
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MATCH INFO
Uefa Champions League final:
Who: Real Madrid v Liverpool
Where: NSC Olimpiyskiy Stadium, Kiev, Ukraine
When: Saturday, May 26, 10.45pm (UAE)
TV: Match on BeIN Sports
Five hymns the crowds can join in
Papal Mass will begin at 10.30am at the Zayed Sports City Stadium on Tuesday
Some 17 hymns will be sung by a 120-strong UAE choir
Five hymns will be rehearsed with crowds on Tuesday morning before the Pope arrives at stadium
‘Christ be our Light’ as the entrance song
‘All that I am’ for the offertory or during the symbolic offering of gifts at the altar
‘Make me a Channel of your Peace’ and ‘Soul of my Saviour’ for the communion
‘Tell out my Soul’ as the final hymn after the blessings from the Pope
The choir will also sing the hymn ‘Legions of Heaven’ in Arabic as ‘Assakiroo Sama’
There are 15 Arabic speakers from Syria, Lebanon and Jordan in the choir that comprises residents from the Philippines, India, France, Italy, America, Netherlands, Armenia and Indonesia
The choir will be accompanied by a brass ensemble and an organ
They will practice for the first time at the stadium on the eve of the public mass on Monday evening
UAE currency: the story behind the money in your pockets
Company%20profile
%3Cp%3E%3Cstrong%3ECompany%20name%3A%3C%2Fstrong%3E%20Fasset%0D%3Cbr%3E%3Cstrong%3EStarted%3A%20%3C%2Fstrong%3E2019%0D%3Cbr%3E%3Cstrong%3EFounders%3A%3C%2Fstrong%3E%20Mohammad%20Raafi%20Hossain%2C%20Daniel%20Ahmed%0D%3Cbr%3E%3Cstrong%3EBased%3A%3C%2Fstrong%3E%20Dubai%0D%3Cbr%3E%3Cstrong%3ESector%3A%20%3C%2Fstrong%3EFinTech%0D%3Cbr%3E%3Cstrong%3EInitial%20investment%3A%3C%2Fstrong%3E%20%242.45%20million%0D%3Cbr%3E%3Cstrong%3ECurrent%20number%20of%20staff%3A%3C%2Fstrong%3E%2086%0D%3Cbr%3E%3Cstrong%3EInvestment%20stage%3A%3C%2Fstrong%3E%20Pre-series%20B%0D%3Cbr%3E%3Cstrong%3EInvestors%3A%3C%2Fstrong%3E%20Investcorp%2C%20Liberty%20City%20Ventures%2C%20Fatima%20Gobi%20Ventures%2C%20Primal%20Capital%2C%20Wealthwell%20Ventures%2C%20FHS%20Capital%2C%20VN2%20Capital%2C%20local%20family%20offices%3C%2Fp%3E%0A
The specs
- Engine: 3.9-litre twin-turbo V8
- Power: 640hp
- Torque: 760nm
- On sale: 2026
- Price: Not announced yet
6.30pm: Al Maktoum Challenge Round-3 Group 1 (PA) | US$95,000 | (Dirt) 2,000m
7.05pm: Meydan Classic Listed (TB) ) | $175,000) | (Turf) 1,600m
7.40pm: Handicap (TB) ) | $135,000 ) | (D) 1,600m
8.15pm: Nad Al Sheba Trophy Group 3 (TB) ) | $300,000) | (T) 2,810m
8.50pm: Curlin Handicap Listed (TB)) | $160,000) | (D) 2,000m
9.25pm: Handicap (TB)) | $175,000) | (T) 1,400m
10pm: Handicap (TB) ) | $135,000 ) | (T) 2,000m
Ferrari 12Cilindri specs
Engine: naturally aspirated 6.5-liter V12
Power: 819hp
Torque: 678Nm at 7,250rpm
Price: From Dh1,700,000
Available: Now
Sweet%20Tooth
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More from Neighbourhood Watch:
AI traffic lights to ease congestion at seven points to Sheikh Zayed bin Sultan Street
The seven points are:
Shakhbout bin Sultan Street
Dhafeer Street
Hadbat Al Ghubainah Street (outbound)
Salama bint Butti Street
Al Dhafra Street
Rabdan Street
Umm Yifina Street exit (inbound)
The%20specs%20
%3Cp%3E%3Cstrong%3EEngine%3A%20%3C%2Fstrong%3E2.0-litre%204cyl%20turbo%0D%3Cbr%3E%3Cstrong%3EPower%3A%20%3C%2Fstrong%3E261hp%20at%205%2C500rpm%0D%3Cbr%3E%3Cstrong%3ETorque%3A%20%3C%2Fstrong%3E400Nm%20at%201%2C750-4%2C000rpm%0D%3Cbr%3E%3Cstrong%3ETransmission%3A%20%3C%2Fstrong%3E7-speed%20dual-clutch%20auto%0D%3Cbr%3E%3Cstrong%3EFuel%20consumption%3A%20%3C%2Fstrong%3E10.5L%2F100km%0D%3Cbr%3E%3Cstrong%3EOn%20sale%3A%20%3C%2Fstrong%3ENow%0D%3Cbr%3E%3Cstrong%3EPrice%3A%20%3C%2Fstrong%3EFrom%20Dh129%2C999%20(VX%20Luxury)%3B%20from%20Dh149%2C999%20(VX%20Black%20Gold)%3C%2Fp%3E%0A
The National's picks
4.35pm: Tilal Al Khalediah
5.10pm: Continous
5.45pm: Raging Torrent
6.20pm: West Acre
7pm: Flood Zone
7.40pm: Straight No Chaser
8.15pm: Romantic Warrior
8.50pm: Calandogan
9.30pm: Forever Young
BMW M5 specs
Engine: 4.4-litre twin-turbo V-8 petrol enging with additional electric motor
Power: 727hp
Torque: 1,000Nm
Transmission: 8-speed auto
Fuel consumption: 10.6L/100km
On sale: Now
Price: From Dh650,000
The specs
AT4 Ultimate, as tested
Engine: 6.2-litre V8
Power: 420hp
Torque: 623Nm
Transmission: 10-speed automatic
Price: From Dh330,800 (Elevation: Dh236,400; AT4: Dh286,800; Denali: Dh345,800)
On sale: Now
The specs
Engine: 2.0-litre 4cyl turbo
Power: 261hp at 5,500rpm
Torque: 405Nm at 1,750-3,500rpm
Transmission: 9-speed auto
Fuel consumption: 6.9L/100km
On sale: Now
Price: From Dh117,059
RESULTS
Bantamweight: Victor Nunes (BRA) beat Azizbek Satibaldiev (KYG). Round 1 KO
Featherweight: Izzeddin Farhan (JOR) beat Ozodbek Azimov (UZB). Round 1 rear naked choke
Middleweight: Zaakir Badat (RSA) beat Ercin Sirin (TUR). Round 1 triangle choke
Featherweight: Ali Alqaisi (JOR) beat Furkatbek Yokubov (UZB). Round 1 TKO
Featherweight: Abu Muslim Alikhanov (RUS) beat Atabek Abdimitalipov (KYG). Unanimous decision
Catchweight 74kg: Mirafzal Akhtamov (UZB) beat Marcos Costa (BRA). Split decision
Welterweight: Andre Fialho (POR) beat Sang Hoon-yu (KOR). Round 1 TKO
Lightweight: John Mitchell (IRE) beat Arbi Emiev (RUS). Round 2 RSC (deep cuts)
Middleweight: Gianni Melillo (ITA) beat Mohammed Karaki (LEB)
Welterweight: Handesson Ferreira (BRA) beat Amiran Gogoladze (GEO). Unanimous decision
Flyweight (Female): Carolina Jimenez (VEN) beat Lucrezia Ria (ITA), Round 1 rear naked choke
Welterweight: Daniel Skibinski (POL) beat Acoidan Duque (ESP). Round 3 TKO
Lightweight: Martun Mezhlumyan (ARM) beat Attila Korkmaz (TUR). Unanimous decision
Bantamweight: Ray Borg (USA) beat Jesse Arnett (CAN). Unanimous decision
