Beautiful Virgin Islands

Tuesday, Jun 03, 2025

Covid loses 90% of ability to infect within minutes in air – study

Covid loses 90% of ability to infect within minutes in air – study

Exclusive: findings highlight importance of short-range Covid transmission

Coronavirus loses 90% of its ability to infect us within 20 minutes of becoming airborne – with most of the loss occurring within the first five minutes, the world’s first simulations of how the virus survives in exhaled air suggest.

The findings re-emphasise the importance of short-range Covid transmission, with physical distancing and mask-wearing likely to be the most effective means of preventing infection. Ventilation, though still worthwhile, is likely to have a lesser impact.

“People have been focused on poorly ventilated spaces and thinking about airborne transmission over metres or across a room. I’m not saying that doesn’t happen, but I think still the greatest risk of exposure is when you’re close to someone,” said Prof Jonathan Reid, director of the University of Bristol’s Aerosol Research Centre and the study’s lead author.

“When you move further away, not only is the aerosol diluted down, there’s also less infectious virus because the virus has lost infectivity [as a result of time].”

Until now, our assumptions about how long the virus survives in tiny airborne droplets have been based on studies that involved spraying virus into sealed vessels called Goldberg drums, which rotate to keep the droplets airborne. Using this method, US researchers found that infectious virus could still be detected after three hours. Yet such experiments do not accurately replicate what happens when we cough or breathe.

Instead, researchers from the University of Bristol developed apparatus that allowed them to generate any number of tiny, virus-containing particles and gently levitate them between two electric rings for anywhere between five seconds to 20 minutes, while tightly controlling the temperature, humidity and UV light intensity of their surroundings. “This is the first time anyone has been able to actually simulate what happens to the aerosol during the exhalation process,” Reid said.


The study, which has not yet been peer-reviewed, suggested that as the viral particles leave the relatively moist and carbon dioxide-rich conditions of the lungs, they rapidly lose water and dry out, while the transition to lower levels of carbon dioxide is associated with a rapid increase in pH. Both of these factors disrupt the virus’s ability to infect human cells, but the speed at which the particles dry out varies according to the relative humidity of the surrounding air.

When this was lower than 50% – similar to the relatively dry air found in many offices – the virus had lost around half of its infectivity within five seconds, after which the decline was slower and more steady, with a further 19% loss over the next five minutes. At 90% humidity – roughly equivalent to a steam or shower room – the decline in infectivity was more gradual, with 52% of particles remaining infectious after five minutes, dropping to about 10% after 20 minutes, after which these was no difference between the two conditions.

However, the temperature of the air made no difference to viral infectivity, contradicting the widely held belief that viral transmission is lower at high temperatures.

“It means that if I’m meeting friends for lunch in a pub today, the primary [risk] is likely to be me transmitting it to my friends, or my friends transmitting it to me, rather than it being transmitted from someone on the other side of the room,” said Reid. This highlights the importance of wearing a mask in situations where people cannot physically distance, he added.

The findings support what epidemiologists have been observing on the ground, said Dr Julian Tang, a clinical virologist at the University of Leicester, adding that “masks are very effective … as well as social distancing. Improved ventilation will also help – particularly if this is close to the source.”

Dr Stephen Griffin, associate professor of virology at the University of Leeds, emphasised the importance of ventilation, saying: “Aerosols will fill up indoor spaces rapidly in the absence of proper ventilation, so assuming the infected individual remains within the room, the levels of virus will be replenished.”

The same effects were seen across all three Sars-CoV-2 variants the team has tested so far, including Alpha. They hopes to start experiments with the Omicron variant in the coming weeks.

Newsletter

Related Articles

Beautiful Virgin Islands
0:00
0:00
Close
Dutch government falls as far-right leader Wilders quits coalition
Harvard Urges US to Unfreeze Funds for Public Health Research
Businessman Mauled by Lion at Luxury Namibian Lodge
Researchers Consider New Destinations Beyond the U.S.
53-Year-Old Doctor Claims Biological Age of 23
Trump Struggles to Secure Trade Deals With China and Europe
Russia to Return 6,000 Corpses Under Ukraine Prisoner Swap Deal
Microsoft Lays Off Hundreds More Amid Restructuring
Harvey Weinstein’s Publicist Embraces Notoriety
Macron and Meloni Seek Unity Despite Tensions
Trump Administration Accused of Obstructing Deportation Cases
Newark Mayor Sues Over Arrest at Immigration Facility
Center-Left Candidate Projected to Win South Korean Presidency
Trump’s Tariffs Predicted to Stall Global Economic Growth
South Korea’s President-Elect Expected to Take Softer Line on Trump and North Korea
Trump’s China Strategy Remains a Geopolitical Puzzle
Ukraine Executes Long-Range Drone Strikes on Russian Airbases
Conservative Karol Nawrocki wins Poland’s presidential election
Study Identifies Potential Radicalization Risk Among Over One Million Muslims in Germany
Good news: Annalena Baerbock Elected President of the UN General Assembly
Apple Appeals EU Law Over User Data Sharing Requirements
South Africa: "First Black Bank" Collapses after Being Looted by Owners
Poland will now withdraw from the EU migration pact after pro-Trump nationalist wins Election
"That's Disgusting, Don’t Say It Again": The Trump Joke That Made the President Boil
Trump Cancels NASA Nominee Over Democratic Donations
Paris Saint-Germain's Greatest Triumph Is Football’s Lowest Point
OnlyFans for Sale: From Lockdown Lifeline to Eight-Billion-Dollar Empire
Mayor’s Security Officer Implicated | Shocking New Details Emerge in NYC Kidnapping Case
Hegseth Warns of Potential Chinese Military Action Against Taiwan
OPEC+ Agrees to Increase Oil Output for Third Consecutive Month
Jamie Dimon Warns U.S. Bond Market Faces Pressure from Rising Debt
Turkey Detains Istanbul Officials Amid Anti-Corruption Crackdown
Taylor Swift Gains Ownership of Her First Six Albums
Bangkok Ranked World's Top City for Remote Work in 2025
Satirical Sketch Sparks Political Spouse Feud in South Korea
Indonesia Quarry Collapse Leaves Multiple Dead and Missing
South Korean Election Video Pulled Amid Misogyny Outcry
Asian Economies Shift Away from US Dollar Amid Trade Tensions
Netflix Investigates Allegations of On-Set Mistreatment in K-Drama Production
US Defence Chief Reaffirms Strong Ties with Singapore Amid Regional Tensions
Vietnam Faces Strategic Dilemma Over China's Mekong River Projects
Malaysia's First AI Preacher Sparks Debate on Islamic Principles
White House Press Secretary Criticizes Harvard Funding, Advocates for Vocational Training
France to Implement Nationwide Smoking Ban in Outdoor Spaces Frequented by Children
Meta and Anduril Collaborate on AI-Driven Military Augmented Reality Systems
Russia's Fossil Fuel Revenues Approach €900 Billion Since Ukraine Invasion
U.S. Justice Department Reduces American Bar Association's Role in Judicial Nominations
U.S. Department of Energy Unveils 'Doudna' Supercomputer to Advance AI Research
U.S. SEC Dismisses Lawsuit Against Binance Amid Regulatory Shift
Alcohol Industry Faces Increased Scrutiny Amid Health Concerns
×