Connect with us

Health

Engineer Says Where You Sit in a Room Can Influence Your Risk of Catching COVID-19 – ScienceAlert

Published

 on


It doesn’t take long for airborne coronavirus particles to make their way through a room. At first, only people sitting near an infected speaker are at high risk, but as the meeting or class goes on, the tiny aerosols can spread.

That doesn’t mean everyone faces the same level of risk, however.

As an engineer, I have been conducting experiments tracking how aerosols move, including those in the size range that can carry viruses.

What I’ve found is important to understand as more people return to universities, offices and restaurants and more meetings move indoors as temperatures fall. It points to the highest-risk areas in rooms and why proper ventilation is crucial.

As we saw this past few weeks with President Donald Trump and others in Washington, the coronavirus can spread quickly in close quarters if precautions aren’t taken.

University campuses have also been struggling with COVID-19. Cases among 18- to 22-year-olds more than doubled in the Midwest and Northeast after schools reopened in August.

As the case numbers rise, the risk to anyone who spends time in those rooms rises as well.

An experiment shows who’s at greatest risk

Most current models describing the role of ventilation on the fate of airborne microbes in a room assume the air is well mixed, with the particle concentration uniform throughout.

In a poorly ventilated room or small space, that is likely true. In those scenarios, the entire room is a high-risk region.

However, in larger spaces, such as classrooms, good ventilation reduces risk, but likely not uniformly. My research shows that how high the level of risk gets depends a lot on ventilation.

To understand how the coronavirus can spread, we injected aerosol particles similar in size to those from humans into a room and then monitored them with sensors.

We used a 30-foot by 26-foot university classroom designed to accommodate 30 students that had a ventilation system that met the recommended standards.

When we released particles at the front of the classroom, they reached all the way to the back of the room within 10 to 15 minutes.

However, because of active ventilation in the room, the concentrations at the back, about 20 feet (6.1 metres) from the source, were about one-tenth of the concentrations close to the source.

That suggests that with appropriate ventilation, the highest risk for getting COVID-19 could be limited to a small number of people near the infected speaker.

As the time spent indoors with an infected speaker increases, however, risk extends to the entire room, even if ventilation is good.

[embedded content]

CDC finally acknowledges the aerosol risk

In the past, the transmission of respiratory diseases has focused on the role of larger particles that are generated when we sneeze and cough.

These droplets fall quickly to the ground, and social distancing and mask wearing can largely prevent infection from them.

The bigger concern now is the role of tiny particles known as aerosols that are generated when we talk, sing or even just breathe. These particles, often smaller than 5 micrometers, can escape from cloth face masks and linger in air for up to about 12 hours.

The Centers for Disease Control and Prevention finally acknowledged that risk on October 5 after Trump was hospitalized and several other people in or close to the administration tested positive for COVID-19.

While these smaller particles, on average, carry less virus than larger particles that people emit when they cough or sneeze, the high infectivity of SARS-CoV-2 combined with the high viral load before symptoms appear makes these particles important for airborne disease transmission.

How much ventilation is enough?

To minimize COVID-19 transmission indoors, the CDC’s top recommendation is to eliminate the source of infection. Remote learning has effectively done this on many campuses. For face-to-face teaching, engineering measures such as ventilation, partition shields and filtration units can directly remove particles from the air.

Of all the engineering controls, ventilation is probably the most effective tool to minimize infection spread.

Understanding how ventilation lowers your risks of getting COVID-19 starts with air exchange rates. An air exchange of one per hour means that the air supplied to the room over one hour equals the volume of air in the room.

Air exchange rate ranges from less than one for homes to around 15-25 for hospital operating rooms.

For classrooms, the current regulations of primary air flow correspond to an air exchange of about six per hour. That means that every 10 minutes, the amount of air brought into the room equals that of the volume of the room.

How high the concentration gets depends in part on the number of people in the room, how much they emit and the air exchange rate.

With social distancing reducing classroom populations by half and everyone wearing masks, the air in many indoor spaces is actually cleaner now than it was before the pandemic.

Parts of the room to avoid

It’s important to remember that not all parts of a room are at equal risk.

The corners of the room will likely have a lower air exchange – so particles can linger there longer.

Being close to an air exit vent could mean that airborne particles from the rest of the room could wash over you.

A study of ventilation airflow in a restaurant in China traced its role in several COVID-19 illnesses among the patrons there.

About 95 percent of particles in the room will be removed by a properly functioning ventilation system in 30 minutes, but an infected person in the room means those particles are also continuously emitted.

The pace of particle removal can be accelerated by increasing the air exchange rate or adding other engineering controls such as filtration units. Opening windows will also often increase the effective air exchange rate.

As schools, restaurants, malls and other communal spaces start accommodating more people indoors, understanding the risks and following the CDC’s recommendations can help minimize infection spread.

This story has been updated with the CDC’s newly released guidance on aerosols.

Suresh Dhaniyala, Bayard D. Clarkson Distinguished Professor of Mechanical and Aeronautical Engineering, Clarkson University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Let’s block ads! (Why?)



Source link

Continue Reading

Health

October 25, 2020 – COVID-19 Update from Dr. Theresa Tam – Net Newsledger

Published

 on


OTTAWA – COVID-19: In lieu of an in-person update to the media, Dr. Theresa Tam, Canada’s Chief Public Health Officer, issued the following statement Sunday:

“As the resurgence of COVID-19 activity continues in Canada, we are tracking a range of epidemiological indicators to monitor where the disease is most active, where it is spreading and how it is impacting the health of Canadians and public health, laboratory and healthcare capacity. The following is the latest summary on national numbers and trends, and the actions we all need to be taking to maintain COVID-19 at manageable levels across the country.

Since the first cases were reported in March 2020, there have been 213,959 cases of COVID-19, including 9,922 deaths reported in Canada; these cumulative numbers tell us about the overall burden of COVID-19 illness to date. Though the cumulative number is high and continues to increase, it is important to remember that the vast majority of Canadians remain susceptible to COVID-19. This is why it is important for everyone to continue with individual precautions that will keep ourselves, our families and our communities safer.

At this time, there are 24,401 active cases across the country. The latest national-level data indicate daily averages of 2,488 new cases (Oct 16-22) and 74,719 people tested, with 3.1% testing positive (Oct 11-17). Outbreaks continue to contribute to COVID-19 spread in Canada. These vary in size from just a few cases to larger clusters occurring in a range of settings including long term care and assisted living facilities, schools, congregate living settings, industrial work settings and large social gatherings. Larger clusters tell us that closed and crowded settings and/or not sufficiently maintaining public health practises, such as physical distancing and mask wearing, can amplify spread of the virus.

While I know keeping physically apart is difficult, particularly when we want to mark life’s important moments like weddings and funerals, now is not the time for hosting large in-person gatherings. Right now, doing the best thing to keep our family, friends and community safer means keeping safely apart, connecting virtually, and finding safer ways to care and support each other.

The number of people experiencing severe illness continues to increase. Provincial and territorial data, indicate that an average of 1,010 people with COVID-19 were being treated in Canadian hospitals each day during the most recent 7-day period (Oct 16-22), including 209 of whom were being treated in intensive care units. During the same period, there were an average of 23 COVID-19-related deaths reported daily.

As hospitalisations and deaths tend to lag behind increased disease activity by one to several weeks, the concern is that we have yet to see the extent of severe impacts associated with the ongoing increase in COVID-19 disease activity. As well, influenza and respiratory infections typically increase during the Fall and Winter, placing increased demands on hospitals. This is why it is so important for people of all ages to maintain public health practises that keep respiratory infection rates low.

Canada needs a collective effort to sustain the public health response through to the end of the pandemic, while balancing the health, social and economic consequences. We can all do our part by keeping our number of in-person close contacts low and committing to proven effective public health practises; stay home/self-isolate if you have any symptoms, maintain physical distancing, wear a face mask as appropriate, and keep up with hand, cough and surface hygiene. Canadians can also go the extra mile by sharing credible information on COVID-19 risks and prevention practises and measures to reduce COVID-19 in communities and by downloading the COVID Alert app to help limit the spread of COVID-19.

Read my backgrounder to access more COVID-19 Information and Resources on ways to reduce the risks and protect yourself and others.”

Let’s block ads! (Why?)



Source link

Continue Reading

Health

Canadian Press NewsAlert: Quebec reaches more than 100,000 total cases of COVID-19 – Airdrie Today

Published

 on


MONTREAL — Quebec reached more than 100,000 total cases of COVID-19 on Sunday, becoming the first province in Canada to hit the somber milestone since the pandemic began in March.

But despite remaining the country’s coronavirus epicentre, public health experts say a recent downward trend of infections is an encouraging sign.

“It’s a moment where we all sit up and say wow, 100,000 – that’s a lot of zeroes,” said Erin Strumpf, an associate professor at McGill University specialized in health economics.

“But again I think the more important thing to be paying attention to is the trend that we’ve been seeing recently in the province.”

The province reported 879 new cases on Sunday, bringing the total to 100,114 infections since the start of the pandemic.

The curve of new infections appears to have flattened over the past few weeks though, Strumpf said in an interview.

That downward trend, she said, coincides with stricter public health guidelines that aimed to stem the spread of the virus.

The government ordered the closure of bars and gyms, among other places, in hard-hit areas and advised residents to limit their contact with people who do not live in their households.

Montreal and Quebec City are among several Quebec regions that remain under the highest COVID-19 alert.

Strumpf said it is hard to pinpoint what exact measures are responsible for flattening the curve, however.

She added that she expects to see many public health restrictions remain in place moving forward. “It’s very difficult to know right now or to predict how long those closures may stay in place,” she said.

Still, the high COVID-19 infection numbers bring up painful memories for Quebecers who lost loved ones during the pandemic.

July Mak, whose 68-year-old father Paul contracted COVID-19 in a long-term care home in Montreal and died at the end of March, said the pain of her father’s death has not eased with time.

“To see these numbers this high… it blows my mind,” Mak said in an interview Sunday.

She said she wants the Quebec government to recognize that its COVID-19 data is more than just numbers — and thousands of people across the province have been directly affected.

“They mattered,” Mak said, about the thousands who have died.

On Sunday, Quebec Health Minister Christian Dube said on Twitter that the number of new infections is “stable but remains high.”

Those cases can turn into hospitalizations and deaths, Dube warned, urging Quebecers to remain vigilant to reduce transmission.

Quebec health officials also reported 11 additional deaths attributed to the novel coronavirus, bringing the total to 6,143.

Five of those additional deaths took place in the past 24 hours, five were reported between Oct. 18-23 and one occurred at an unspecified date.

Hospitalizations went up by two across the province, for a total of 551. Of those, 97 people were in intensive care — an increase of four compared to the previous day.

The province said it conducted 25,378 COVID-19 tests on Friday, the last date for which the testing data is available.

This report by The Canadian Press was first published Oct. 25, 2020.

Jillian Kestler-D’Amours, The Canadian Press

Let’s block ads! (Why?)



Source link

Continue Reading

Health

With 879 new COVID-19 cases, Quebec passes grim 100,000 milestone – Timmins Times

Published

 on


The province also reported 11 more deaths as the cumulative total of cases reached 100,114.

With Quebec surpassing the 100,000 mark in new COVID-19 cases Sunday, it’s clear the winter ahead will be challenging, two epidemiologists said.

“I’m concerned that we’ve reached the 100,000 mark,” said Catherine Hankins, a professor of public health at McGill University and co-chair of the COVID-19 Immunity Task Force.

“We’re just at the start of what will be a cold winter, so we really need to ramp up our public health response,” she said.

A major challenge will be to achieve a balance between distancing measures to check the virus’s spread and mental-health issues caused by loss of social contact, especially as winter weather forces people indoors, Hankins said.

We should take inspiration from the Scandinavian saying: “There’s no such thing as bad weather, only bad clothes,” she suggested.

“We should be able to get out in all types of weather and keep active if we dress appropriately, with the layers that we need,” she said.

Hankins proposed that the phrase “social distancing,” should be replaced by “physical distancing.”

There are still ways to connect with others while practising safety measures like avoiding gatherings, wearing masks, keeping a two-metre distance from people outside our household and hand washing, she said.

“One thing that’s important is that people continue to exercise,” she said.

“For our own mental health, we do need to keep physically active and, although physically distanced, we need to keep socially active, even if it’s by phone or online.”

For people who aren’t comfortable with videoconference apps, the good, old-fashioned telephone is a great way to stay in touch, she said.

“Pick up the phone. Don’t hesitate to call somebody. Don’t feel like you’re interrupting or bother them. Just pick up the phone and give them a call,” Hankins added.

Quebec reported 879 new cases of COVID-19 on Sunday and 1,009 new cases Saturday, bringing the total to 100,114 since the first case was reported on Feb. 29.

Infections from Quebec continue to account for nearly half of Canada’s total, which stood at 213,959 on Saturday night.

Ontario, the province with the second-most infections, topped 1,000 cases for the first time on Sunday to reach a total of 70,373.

“I’m concerned to see that Ontario is getting up to our levels now. And I am really concerned when I look at places in Europe that thought they had it under some kind of reasonable control,” Hankins said.

Quebec has recorded more than 1,000 cases in seven of the last 10 days.

The province reported 11 more deaths on Sunday. Five of those fatalities occurred in the last 24 hours, another five occurred between Oct. 18 and 24 and one was from an unknown date.

The number of deaths associated with the virus now stands at 6,143.

The number of hospitalizations increased by two to 551. Of the patients hospitalized because of the virus, 97 are in intensive care, an increase of four from Saturday.

Of the new cases reported on Sunday, 146 were in Montreal, where a total of 40,869 have now been reported.

For the first time in a week, Montreal was not the region with the most new cases. Montérégie, with 162, reported the highest total.

Jay Kaufman, an epidemiologist at McGill University, said that with 800-1000 cases a day for almost three weeks now, “Quebec is not doing so badly” compared to many European countries and the United States.

However, with Quebec continuing to have the worst case counts in Canada, “there is still lots of room for concern,” he said.

The fact cases have plateaued in Quebec show distancing measures are working, he said.

“The cases are not declining, however, and hospitalizations are way up, and so I suspect that we will not be able to reopen closed businesses for some time still, which is terrible news for those businesspeople,” he added.

Hankins said there should be more emphasis on the contact-tracing cell phone app to fight the virus’s spread.

Additional measures to protect vulnerable residents of long-term care facilities that were hard hit during the first wave are essential, she added.

“We know that they’re an Achilles heel,” she said.

“This is the most vulnerable population and we really need to make sure that we get it right this time as best we can.”

mscott@postmedia.com

With additional reporting by David Rudin

Related

All our coronavirus-related news can be found at montrealgazette.com/tag/coronavirus.

Sign up for our email newsletter dedicated to local COVID-19 coverage at montrealgazette.com/coronavirusnews.

Help support our local journalism by subscribing to the Montreal Gazette here.

Let’s block ads! (Why?)



Source link

Continue Reading

Trending