Connect with us

Science

COVID-19 likely spread by building ventilation, say Alberta researchers working on an HVAC fix – Edmonton Sun

Published

on


A group of Alberta researchers are working on ways that buildings could change their HVAC set-ups to curb the risk of infection

The outbreak of COVID-19 at a restaurant in the southern Chinese city of Guangzhou was a puzzle.

The suspected index patient was a visitor from the coronavirus’s epicentre in Wuhan. But the eight other customers who later tested positive were not sitting close enough for droplet transmission, and most of the patrons and staff avoided infection altogether.

A team of local scientists eventually came to an eye-opening conclusion about the episode: tiny particles of virus had hitched a ride on currents created by the eatery’s air-conditioning.

That runs counter to the prevailing view that the novel coronavirus is transmitted only by heavier “droplets.” But for a group of civil engineers at the University of Alberta, the finding was no surprise. In their world, they say, it’s well known that building ventilation systems are efficient disseminators of viruses and other pathogens, and they believe the COVID-19 bug is no exception.

Aided by a $440,000 federal-government grant, they’re now working on ways that buildings could change their HVAC set-ups to curb the risk of infection, what the researchers call a “non-pharmaceutical” intervention against the disease.

We want to save lives, let’s cut right to the chase

“We want to save lives, let’s cut right to the chase,” said Prof. Brian Fleck, part of the project. “There are so many, many, many buildings … This affects absolutely everybody. Billions of people. If we are able to cut down the transmission rate by a per cent, that’s a lot of people.”

The engineers’ belief in the importance of building ventilation as a transmitter of the COVID-19 virus is not universally held.

The World Health Organization and other public-health bodies, citing the science to date, say the pathogen is spread almost entirely by droplets, heavier particles emitted mostly when infected people cough or sneeze, and which fall down within a short distance. Hence the two-metre rule for social distancing, and the emphasis on washing hands after touching surfaces where virus may have alighted.

“The HVAC systems in most non-medical buildings play only a small role in infectious disease transmission, including COVID-19,” argued the American Society of Heating, Refrigerating, and Air-Conditioning Engineers last month.

It’s just smaller and lighter aerosol particles that can spread through a ventilation system and “the truth is that we still don’t really know if the (COVID-19) virus can be spread by aerosols,” said Matthew Miller, a virus expert at McMaster University in Hamilton.

But Chinese and Australian air-quality experts, citing in part the experience with SARS, another coronavirus, argued in a paper earlier this month that as droplets from an infected person start to evaporate, the resulting smaller particles can indeed become airborne.

They point to evidence that passengers confined to their cabins on cruise ships like the Diamond Princess may have been infected through the vessels’ air ducts.

“It is highly likely that the SARS-CoV-2 virus also spreads by air,” they conclude, urging “all possible” action in response, including modifications to ventilation systems. “We predict that … failure to immediately recognize and acknowledge the importance of airborne transmission and to take adequate actions against it will result in additional cases.”

Then there was the Guangzhou restaurant case, detailed in a U.S. Centers for Disease Control online journal recently. Researchers concluded flow from an air conditioner moved over three tables, carrying virus from the infected patron at the middle one to the far table, then back to the diners closest to the air conditioner.

Even if it turned out SARS-CoV-2 does not spread that way, influenza viruses can, and the University of Alberta research would be valuable for that reason alone, said Miller.

Heating, ventilation and air conditioning (HVAC) engineers have long known that tiny particles of pathogen travel in the air that is circulated, heated and cooled in modern buildings, said Fleck. He pointed to Legionnaires disease, a bacterial pneumonia first traced to a hotel’s air-conditioning system.

The particle can stay airborne long enough to go all the way through the system and then pop out in somebody else’s office

“This has been on people’s radar for quite a while,” he said. “Somebody on a different floor sneezes …The particle can stay airborne long enough to go all the way through the system and then pop out in somebody else’s office.”

There are various ways that the risk can be lessened, including use of filters that catch a greater number of those particles, and drawing more fresh air into a system. It also is likely that higher levels of humidity – a factor that only some Canadian buildings can adjust – will help kill off the virus, said Fleck.

But each of those changes carries a cost. Adding more fresh air can require additional heat or air conditioning. Heavier filters means more energy is needed to push the air through them. And more humidity can lead to mould, he noted.

“This will make for difficult decision making.”

Funded by the Canadian Institute for Health Research, the University of Alberta project is led by engineering professor Lexuan Zhong and also involves pediatrics professor Lisa Hartling. It consists of three phases: systematically reviewing literature on air circulation and viruses, determining what strategies would be effective and then carrying out a detailed audit of all the buildings on the Edmonton campus to create a real-world model of what should be done.

The team hopes to have solid results by the summer of 2021, said Fleck.

(Modified 12:40 April 26 to add comments by Matthew Miller.)

Let’s block ads! (Why?)



Source link

Continue Reading

Science

SpaceX's Starship rocket prototype explodes on Texas test pad – Windsor Star

Published

on


Article content

A prototype of SpaceX’s upcoming heavy-lift rocket, Starship, exploded on Friday during ground tests in south Texas as Elon Musk’s space company pursued an aggressive development schedule to fly the launch vehicle for the first time.

The testing explosion was unrelated to SpaceX’s upcoming launch of two NASA astronauts from Florida’s Kennedy Space Center using a different rocket system, the Falcon 9 with the Crew Dragon capsule fixed on top.

A prototype vanished in an explosive fireball at SpaceX’s Boca Chica test site on Friday, as seen in a livestream recorded by the website NASA Spaceflight. There was no immediate indication of injuries. SpaceX did not immediately respond to a request for comment.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

What Time Is the SpaceX Launch? How to Watch – The New York Times

Published

on


On Saturday, for the first time since the retirement of the space shuttles in July 2011, NASA astronauts are scheduled to blast off from American soil on an American rocket to the International Space Station. In contrast to astronaut launches in the past when NASA ran the show, this time a private company, SpaceX, will be in charge of mission control. The company, founded by Elon Musk, built the Falcon 9 rocket and the capsule, Crew Dragon, which the two astronauts will travel in.

The mission is scheduled to lift off at 3:22 p.m. Eastern time from the Kennedy Space Center in Florida. Coverage of the launch on NASA Television will begin at 11 a.m. The Times will provide live video of the launch.

The first attempt to launch, on Wednesday, was called off about 15 minutes before it was to occur because the weather wasn’t playing nice. SpaceX’s launch directors deemed the risk of lightning and other weather hazards too high to allow the astronauts to lift off safely.

The weather officers said that they expected conditions to clear up about 10 minutes after the scheduled launch time. But in order for the capsule to catch the space station at the right moment the next day, the launch had to go off at the precise time of 4:33 p.m. Eastern time.

Credit…Charlie Riedel/Associated Press

Not the most promising. Weather forecasts currently give a 50 percent chance of favorable conditions at the launch site. The next opportunity on Sunday is slightly better, with a 60 percent chance of favorable conditions.

Lifting off in bad weather can be catastrophic to rockets. During the countdown, about 10 members of the 45th Weather Squadron, part of the United States Space Force, keep a close eye on conditions to see if they fall within predetermined launch criteria. If the weather conditions violate the criteria, SpaceX’s launch director will call off the launch.

The launch has to occur at a precise moment to allow the Crew Dragon to meet up with the space station, and there is no leeway for delays.

For the safety of the crew, the launch team also has to consider weather and ocean conditions just off the coast, where the capsule would splash down if there were an emergency on the launchpad or farther away in the Atlantic if a problem occurred on the way to orbit.

Credit…John Raoux/Associated Press

The astronauts are Robert L. Behnken and Douglas G. Hurley, who have been friends and colleagues since both were selected by NASA to be astronauts in 2000.

They both have backgrounds as military test pilots and have each flown twice previously on space shuttle missions, although this is the first time they have worked together on a mission. Mr. Hurley flew on the space shuttle’s final mission in 2011.

In 2015, they were among the astronauts chosen to work with Boeing and SpaceX on the commercial space vehicles that the companies were developing. In 2018, they were assigned to the first SpaceX flight.

SpaceX has never taken people to space before. Its Crew Dragon is a gumdrop-shaped capsule — an upgraded version of SpaceX’s original Dragon capsule, which has been used many times to carry cargo, but not people, to the space station.

Crew Dragon has space for up to seven people but will have only four seats for NASA missions. If this launch succeeds, it will ferry four astronauts to the space station later in the year.

The Crew Dragon is scheduled to arrive at the International Space Station 19 hours after launch on Sunday, at about 10:30 a.m. Eastern time. During their trip, the astronauts will test to test how the spacecraft flies and verify that the systems are performing as designed. Unless something goes wrong, the Crew Dragon’s computers usually handle all of the maneuvering and docking procedures.

The astronauts also said they planned to test out the capsule’s toilet.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

SpaceX’s Starship SN4 launch vehicle prototype explodes after static engine fire test – TechCrunch

Published

on


SpaceX had just conducted yet another static fire test of the Raptor engine in its Starship SN4 prototype launch vehicle on Friday when the test vehicle exploded on the test stand in Boca Chica, Texas. This was the fourth static fire test of this engine on this prototype, so it’s unclear what went wrong versus other static fire attempts.

This was a test in the development of Starship, a new spacecraft that SpaceX has been developing in Boca Chica. Eventually, the company hopes to use it to replace its Falcon 9 and Falcon Heavy rocket, but Starship is still very early in its development phase, whereas those vehicles are flight-proven, multiple times over.

SpaceX had just secured FAA approval to fly its Starship prototype for short, suborbital test flights. The goal was to fly this SN4 prototype for short distances following static fire testing, but that clearly won’t be possible now, as the vehicle appears to have been completely destroyed in the explosion following Friday’s test, as you can see below in the stream from NASASpaceflight.com.

[embedded content]

The explosion occurred around 1:49 PM local time in Texas, roughly two minutes after it had completed its engine test fire. We’ve reached out to SpaceX to find out more about the cause of today’s incident, and whether anyone was hurt in the explosion. SpaceX typically takes plenty of safety precautions when running these tests, including ensuring the area is well clear of any personnel or other individuals.

This isn’t the first time one of SpaceX’s Starship prototypes has met a catastrophic end; a couple of previous test vehicles succumbed to pressure testing while being put through their paces. This is why space companies test frequently and stress test vehicles during development — to ensure that the final operational vehicles are incredibly safe and reliable when they need to be.

SpaceX is already working on additional prototypes, including assembling SN5 nearby in Boca Chica, so it’s likely to resume its testing program quickly once it can clear the test stand and move in the newest prototype. This is a completely separate endeavor from SpaceX’s work on the Commercial Crew program, so that historic first test launch with astronauts on board should proceed either Saturday or Sunday as planned, depending on weather.

Let’s block ads! (Why?)



Source link

Continue Reading

Trending