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COVID-19 spreads through the air. Here's what you can do about it this winter – CBC.ca

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This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven’t subscribed yet, you can do that by clicking here.


Canadians looking for guidance on how to reduce their risk of COVID-19 indoors this winter may be feeling left out in the cold.

The Public Health Agency of Canada (PHAC) now recommends opening windows to increase ventilation and using HEPA filters to clean indoor air, but it stops short of advocating for better-quality masks or saying outright that the virus is primarily airborne.

“From what I’ve seen, Canada is now an outlier in terms of not acknowledging transmission through the air,” said Linsey Marr, an expert on virus transmission at Virginia Tech in Blacksburg, Va. “I think the messaging could be more clear.”

Canada’s guidelines on masking also haven’t been updated in more than a year, with non-medical masks containing a filter still recommended — despite research showing cloth masks are less effective than surgical masks against the airborne spread of COVID-19.

“It sounds like they’re still talking like there’s a shortage of medical masks,” said Marr, a civil and environmental engineering professor. “We know any mask is better than no mask, but also some masks are better than other masks — and so if you haven’t already, you could consider upgrading your mask.”

Marr said Canada is “missing out” on the opportunity to promote better protection from medical masks with higher filtration levels, such as surgical masks or N95s, but also when it comes to explaining exactly why filtration, ventilation and masking are so important.

“That’s because the virus is in the air,” she said. “I think if people understand that, they will be much more likely and willing to take measures that are effective at reducing transmission.”

Linsey Marr, an expert on virus transmission at Virginia Tech, says Canada is ‘missing out’ on the opportunity to promote better protection from medical masks with higher filtration levels, but also when it comes to explaining why filtration, ventilation and masking are so important. (Graham Hughes/The Canadian Press)

Aerosol transmission ‘changes the game’ on indoor risk

Almost two years into the pandemic, our understanding of the airborne spread of the virus has changed dramatically, with more infectious variants increasing risk and physical distancing alone not proven to be sufficient — especially indoors.

The virus can be transmitted through the air in two key ways: microscopic airborne particles called aerosols that linger in the air like smoke, or larger respiratory droplets that fall to the ground quickly (prompting the original two-metre physical-distancing guidelines).

But experts say Canada’s public health guidance has struggled to keep up with the evolving science, leading to contradictory advice, such as PHAC’s recommendation that physical distancing is the “best way to help prevent the spread of COVID-19.”

“If that’s the case, then you should be OK with being in a room with a COVID-infected person with your mask off if you are six feet apart,” said Raywat Deonandan, a global health epidemiologist and associate professor at the University of Ottawa.

“If that is not the case, then you accept aerosol transmission. But the problem is, we don’t have 100 per cent consensus amongst experts. So it might be confusing for people who get conflicting information.”

Toronto respirologist Dr. Samir Gupta says once we realized aerosol transmission was a primary driver of the spread of the virus through the air, public health guidelines for Canadians should have followed suit.

The virus can be transmitted through the air in two key ways: microscopic airborne particles called aerosols that linger in the air like smoke, or larger respiratory droplets that fall to the ground quickly. (Maggie MacPherson/CBC)

“This whole pandemic has turned aerosol science on its head,” he said. “It became clear that there were transmission events happening much further out than two metres, and so it couldn’t be just droplets.”

Gupta said the “pendulum swung” toward aerosol transmission being a major factor in how the virus is transmitted, and the practical implications of that are “huge” for the Canadian public when gathering indoors.

“You can be very far away from the infection source, but if you’re in there for long enough, you will catch it through aerosols,” he said. “And that changes the game in terms of how we control spread.”

Layering protections can ‘reduce the risk by a lot’ 

Other countries go far beyond Canada’s guidance: The U.S. Centers for Disease Control and Prevention now says N95s can be worn by the general public, and Britain recently launched an awareness campaign on preventing airborne transmission indoors.

Canada quietly updated its guidelines on the risk of airborne spread a year ago, adding the word “aerosols” for the first time, but it has stopped short of recommending medical masks for the general public or creating a similar campaign specifically around airborne spread.

“It is both troubling and tragic that our public health leaders have failed repeatedly to safeguard Canadians through simple, cost-effective and proven airborne protective measures,” said Mario Possamai, a forensic investigator and senior adviser on the 2007 SARS Commission.

“They should be held accountable for the deaths and infections their shameful negligence has caused.”

WATCH | How delays in acknowledging airborne COVID-19 transmission risked lives: 

How delays in acknowledging airborne COVID-19 transmission risked lives

5 months ago

An examination of the timeline of Ontario’s COVID-19 response and how the delay to acknowledge the risk of aerosol transmission may have cost lives, despite lessons learned from the 2003 SARS epidemic. 8:51

Experts say layering different levels of protection on top of each other, also known as the Swiss cheese model, can further prevent the spread of COVID-19 as colder weather pushes us more toward indoor activities in the coming weeks and months.

“None of them by itself is 100 per cent effective,” Marr of Virginia Tech said. “But when you combine them, you can reduce the risk by a lot.”

Deonandan said the use of proper masks, ventilation and filtration — combined with high vaccination rates and vaccine passports for indoor spaces — will help to keep transmission levels low and take care of the “lion’s share of the risk.”

“A year ago, there were so many mysteries about this disease … but now it’s not that mysterious how people get it — and because we know that, we know how to stop it,” he said.

“So we don’t have to have lockdowns, we don’t have to have economic pain anymore. All we’ve got to do is make some good choices on a daily basis.”

Lift measures cautiously, like ‘an on-off switch’

High vaccination rates, the rollout of third doses to vulnerable Canadians and the approval of vaccines for children in the coming weeks will make a big difference in our COVID-19 risk levels across Canada, but experts say we need to be patient.

“When cases are low, it doesn’t mean we should just remove these measures,” said Dr. David Fisman, an epidemiologist at the University of Toronto’s Dalla Lana School of Public Health. “That’s like folding your umbrella in a rainstorm because you’re not wet yet.”

Ontario recently announced plans to lift all of its COVID-19 public health measure by March — including masks — but experts say that decision should be tied to data on transmission levels circulating at the time.

“If we’re going to lift the rules … we need to also be prepared to reinstate them if a new more transmissible variant comes along that escapes the vaccine,” Marr said.

“I think the U.S. got in trouble lifting mask rules in May, and we didn’t have a way to bring them back when we really needed them with the surge of [the delta variant] in late summer.”

Marr said keeping precautions in place and using a “data-driven mask policy” tied to transmission rates in the community “like an on-off switch” will help prevent a resurgence of COVID-19 in the future as we continue to learn to live with the virus.

“It’s important that people understand that the crisis is not over — but it will be,” Deonandan said. “And I know you’re tired of hearing this, but we can live our lives now, but live our lives responsibly.”

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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