Saudi Press

Saudi Arabia and the world
Sunday, Jun 01, 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The study, which has not yet been peer-reviewed, suggested that as the viral particles leave the relatively moist and carbon dioxide-rich conditions of the lungs, they rapidly lose water and dry out, while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

Saudi Press
0:00
0:00
Close
OPEC+ Agrees to Increase Oil Output for Third Consecutive Month
Turkey Detains Istanbul Officials Amid Anti-Corruption Crackdown
Meta and Anduril Collaborate on AI-Driven Military Augmented Reality Systems
EU Central Bank Pushes to Replace US Dollar with Euro as World’s Main Currency
European and Arab Ministers Convene in Madrid to Address Gaza Conflict
U.S. Health Secretary Ends Select COVID-19 Vaccine Recommendations
Trump Warns Putin Is 'Playing with Fire' Amid Escalating Ukraine Conflict
India and Pakistan Engage Trump-Linked Lobbyists to Influence U.S. Policy
U.S. Halts New Student Visa Interviews Amid Enhanced Security Measures
Trump Administration Cancels $100 Million in Federal Contracts with Harvard
SpaceX Starship Test Flight Ends in Failure, Mars Mission Timeline Uncertain
King Charles Affirms Canadian Sovereignty Amid U.S. Statehood Pressure
Iranian Revolutionary Guard Founder Warns Against Trusting Regime in Nuclear Talks
UAE Offers Free ChatGPT Plus Subscriptions to Citizens
Lebanon Initiates Plan to Disarm Palestinian Factions
Iran and U.S. Make Limited Progress in Nuclear Talks
The Daily Debate: The Fall of the Dollar — Strategic Reset or Economic Self-Destruction?
Trump Administration's Tariff Policies and Dollar Strategy Spark Global Economic Debate
OpenAI Acquires Jony Ive’s Startup for $6.5 Billion to Build a Revolutionary “Third Core Device”
Turkey Weighs Citizens in Public as Erdoğan Launches National Slimming Campaign
Saudi-Spanish Business Forum Commences in Riyadh
Saudi Arabia and Spain Sign MoU to Boost SME Sectors
UK Suspends Trade Talks with Israel Amid Gaza Offensive
Iran and U.S. Set for Fifth Round of Nuclear Talks Amid Rising Tensions
Russia Expands Military Presence Near Finland Amid Rising Tensions
Indian Scholar Arrested in Crackdown Over Pakistan Conflict Commentary
Israel Eases Gaza Blockade Amid Internal Dispute Over Military Strategy
President Biden’s announcement of advanced prostate cancer sparked public sympathy—but behind closed doors, Democrats are in panic
A Chinese company made solar tiles that look way nicer than regular panels!
Indian jet shootdown: the all-robot legion behind China’s PL-15E missiles
The Chinese Dragon: The True Winner in the India-Pakistan Clash
Australia's Venomous Creatures Contribute to Life-Saving Antivenom Programme
The Spanish Were Right: Long Working Hours Harm Brain Function
Did Former FBI Director Call for Violence Against Trump? Instagram Post Sparks Uproar
US and UAE Partner to Develop Massive AI Data Center Complex
Apple's $95 Million Siri Settlement: Eligible Users Have Until July 2 to File Claims
US and UAE Reach Preliminary Agreement on Nvidia AI Chip Imports
President Trump and Elon Musk Welcomed by Emir of Qatar Sheikh Tamim with Cybertruck Convoy
Strong Warning Issued: Do Not Use General Chatbots for Medical, Legal, or Educational Guidance
Saudi Arabia Emerges as Global Tech Magnet with U.S. Backing and Trump’s Visit
This was President's departure from Saudi Arabia. The Crown Prince personally escorted him back to the airport.
NVIDIA and Saudi Arabia Launch Strategic Partnership to Establish AI Centers
Trump Meets Syrian President Ahmad al-Shara in Historic Encounter
Trump takes a blow torch to the neocons and interventionists while speaking to the Saudis
US and Saudi Arabia Sign Landmark Agreements Across Multiple Sectors
Why Saudi Arabia Rolled Out a Purple Carpet for Donald Trump Instead of Red
Elon Musk Joins Trump Meeting in Saudi Arabia
Trump says it would be 'stupid' not to accept gift of Qatari plane
Quantum Computing Threatens Bitcoin Security
Michael Jordan to Serve as Analyst for NBA Games
×