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Feb 24, 2022: Name It to Tame It – COVID-19 is Airborne!

Streamed Thursday, February 24, 12:00 – 1:00 pm PST

Protect our Province BC is honoured to be joined for its 12th live briefing by Professor JL Jimenez and Dr. KA Prather, two world renowned scientists and advocates who have played a leading role in putting to rest the “droplet dogma” when it comes to COVID-19 transmission. 

Everyone wants to move on, but to do so we must urgently address how the virus spreads, through aerosols. As Professor Jimenez likes to say, “this is an indoor pandemic.” To be able to convene indoors safely, we must first bring the outside air in and clean the air we breathe and share. There is hope however, as “once we acknowledge it is airborne, it becomes totally manageable”, says Dr. Prather.

Another special guest for this event will be business owner David “Pup” Johnston. His Kamloops bar, the Blue Grotto, was the site of a large COVID-19 outbreak back in mid-October during the Delta wave. This occurred despite following Public Health guidelines based on droplets and contact spread. Using this outbreak as a case study, we will review what aerosol mitigations look like.

We hope you will join us and share this invitation with any business owners you may know. This practical briefing will highlight what aerosol protection means for businesses who want to keep their employees and the community they serve safe while helping bring BC’s pandemic to an end.

We cannot wait any longer for BC Public Health to catch up with the science, we can do this now and help prevent recurrent COVID-19 waves from washing over our province.

Join Protect our Province BC for Briefing #12: Name It to Tame It: It’s Airborne!


Jose Luis Jimenez, Distinguished Professor of Chemistry and Fellow of CIRES; University of Colorado at Boulder

Kimberly A. Prather, Ph.D., Director, NSF Center for Aerosol Impacts on Chemistry of the Environment, Distinguished Professor, Distinguished Chair in Atmospheric Chemistry, Scripps Institution of Oceanography, University of California, San Diego


Dr. Lyne Filiatrault , Retired Emergency Physician, Protect Our Province BC member

Get the slide deck

Briefing Notes:

Topics: aerosol is the main mode of transmission, why getting it right matters, and what we can do about it? Why do the WHO and BC government keep getting it wrong?

Summary: Main mode of COVID transmission

JJ: COVID is not primarily spread by large droplet projectiles that hit you in the eyes, nose, or mouth or fomite spread (touching surfaces). These are both minor pathways.

Myth: Aerosols are only 5 microns or less and everything bigger will fall to the ground within meters.

Fact: Superspreading events typically occur when people aren’t close to one another. For the aerosols to be diluted and still be infectious, they need to be very concentrated when they leave a person. Analogous to cigarette smoke. For 100 years medical professionals have confused gravity with dilution.

Aerosols can be much more numerous and bigger (up to 100 microns). Even if you don’t inhale the virus in close proximity, it will travel meters to be inhaled elsewhere. 5 micron aerosols can travel hundreds of meters.

Singing, speaking, yelling, coughing are real aerosol generating actions.

Why is it so important to get it right?

KP: If we acknowledge COVID is airborne, then it becomes very fixable and allows us to protect ourselves and avoid it. Poorly ventilated indoor spaces are high infection risks, especially where people are talking and/or not wearing masks.

Most people don’t have symptoms when they’re most infectious (2~3d after infection), and COVID is every bit as airborne as measles. In fact, measles can’t be cultured from infected air, but SARS COV 2 can.

How do we fix it?

Myth: hand sanitizer, hand washing, and plexiglass prevent exposure to COVID-19.

Fact: Sanitizing hands and surfaces doesn't protect us against the inhalation of infected air. Filtration (Eg. HEPA filters) and ventilation (eg. opening a window) are the key to reducing community transmission. We can also keep gatherings outside. There's precedent for this, from the Spanish flu pandemic in 1918.

CORSI ROSENTHAL BOXES are a DIY solution that can be built for $70~100, made of 4x HEPA filters and a box fan, taped together. 1 or 2 of them in a room or house will minimize aerosol spread.

Wear a good mask: KN95 or N95, NOT surgical masks — they leak around the sides and aerosols can go right through.

Avoid crowded indoor locations.

KP discusses her consultation work with San Diego Unified School District.

They “addressed the air more than surfaces”. It takes a long time to wipe down every surface. They used filters and employed high quality masks. Kids came to school sick but there were no major outbreaks during the Delta wave. However, more outbreaks occurred during Omicron due to pandemic fatigue and a more infectious mutation.

What can we do about it?

Case study: the Blue Grotto Bar in Kamloops

An outbreak occurred at a live show during the mid-October, 2021 Delta wave.

They followed Public Health recommendations based on droplets, required vaccine passports, held events at half capacity, and allowed patrons to unmask to drink. Tables were 2m apart, choke points were controlled to limit people at any one spot. They separated the tables with plexiglass barriers, and had hand sanitizers for patrons.

The building was old (WWII), had HVAC filter on roof, but unfiltered. Just pushing air in from outside.

29 people got infected from that ONE live event

Interior Health head Dr. Fenton said there was “no outbreak notification” “not classified as an outbreak”.

Some of the people attending also went to other bars beforehand. Where the outbreak started is difficult to determine but genomic sequencing could have cleared it up.

The owner paid for professional disinfection after the fact. Decontamination is important if people are sneezing and coughing and generating DROPLETS. However, in businesses, no cases have been linked to fomite transmission.

Energy spent on hygiene theatre should be spent on filtration etc. Hand sanitizer contains components harmful to health eg. Bleach, benzenes, quaternary ammonium. They are not to be used lightly esp. when droplets aren’t the main mode of transmission.

JJ: When we just breathe, some aerosols come out, but its a factor of 10 less when we are talking, and 50x less than when we are shouting, like in a punk rock concert. We've seen dozens of outbreaks in choirs. Fewer outbreaks in libraries and theatres where people are sedentary and quiet.

JJ: children also generate aerosols, but less than adults. However, children still transmit in the same way.

KP: And kids like to yell.

Thoughts on plexiglass?

JJ: A totally wasted effort providing a false sense of security. The Grotto wasted $7k on plexiglass and $1k on sanitizer… useless. They should have invested in Corsi-Rosenthal boxes — those are much less costly.

What do CO2 meters do?

Humans exhale 40k ppm, much more than atmospheric amount of CO2. Where people are, CO2 accumulate. CO2 meters tell you if there are a lot of exhaled air, if place is ventilated poorly, whether you need to open windows and extractors HOWEVER, filters don’t filter CO2, so CO2 amt. should be looked at with grain of salt.

Halving the number of people in a space makes it numerically more likely that there are fewer infectious people in any given space. Minimizing time in a room is also useful. Think of 5m vs. 5h in a room with a smoker.

Aerosols linger in the air so if people come in after an infectious person generates aerosols, that would also cause infection. However, not after 1 or 2 days.

It’s better to have the fan pointing up in a CR box, instead of on the side. That mixes the air better.

Distribute CR boxes where people are. Put a line of CR boxes between audiences and singers. It takes quite awhile to get a whole room ventilated, but with CR boxes they can take aerosols out of air right away especially if near where infected people are.

CR boxes cost a lot less than HEPA filters and are more quiet. It's still a good idea to leave windows and front doors open for added layers of protection. The cumulative effect of those layers will do a lot of work.

MERV ≥13 filters best. However, some older HVAC systems can’t take these filters — putting them into an HVAC system that can’t take them will cause leaks. Those older HVAC systems would probably do best with MERV 11.

JJ: It's best to balance good filter with pushing a lot of air through HVAC system.

KP on ceiling fans:

There was a case where air conditioners pushed air into one end of a restaurant and people meters away from infectious person got infected. That makes filtration (eg. CR boxes) all the more important.

KP on public washrooms:

No known study proving transfer in bathrooms. However public bathrooms are poorly ventilated. Airborne pathogens like COVID-19 can hover in the air for hours. Some people think they can “take a break” from masking in a washroom, but they're like elevators — not fomite spread with elevator buttons, but aerosol spread within that enclosed space.

SARS1 was linked with sewage, but studies show SARS2 might not be infectious for that long. However flushing can aerosolize the virus. Close the lid before you flush.

KP on masks:

Wear them, they work. Make sure they fit and have no gaps. They do exist for kids, and kids get used to them. It's not damaging to children to ask them to take such a simple measure protect themselves and one another.

With infection control, masks block it at the source. You use it to protect others, but it also filters in both directions.

In close proximity like in bars, filters don’t work as well. So masking would’ve prevented infection, but people in restaurants unmask to eat or drink.

KN95s — there are many fakes, which don't work as well, so buy masks from a reputable supplier.

On KF94: they work well. There are sizes for kids.

JJ on masks:

For people who work in high risk situations, elastomeric N95s are useful (these are N95s with silicon part that seals filter to face).

How long can you use a mask / respirator? 40h? Until it’s soiled?

KP: The strap usually breaks before you lose the filtration capability.

Layers of protection (LF):

Omicron is more infections, so we must bolster every single layer. Vaccinate to your third dose. Wear the best mask or respirator you can find. Avoid sharing air indoors with people outside bubble, esp. when you don’t know about the ventilation or people are not wearing masks. Physical distancing DOES work even with aerosols. Avoid large gatherings.

What must the BC government do?

ASHRAE came out in 4/2020 with epidemic task force, suggesting enough evidence that COVID spread through aerosol. Filtration could have played key role in preventing transmission.

BC must endorse ASHRAE pandemic standards. BC must mandate indoor air quality monitoring with CO2 monitors. BC must recognize SARS COV 2 as occupational health and safety hazard / biohazard.

The street lamp effect: We only look at people within 2m or exposed for 15 minutes in contact tracing, as though we were searching for our keys in a pool of light because that's where the light is (not the keys). These are arbitrary limits, so with a more infectious virus, distance and time limits should be expanded.


What is it going to take to get govt's to acknowledge that ‪#COVIDisAirborne?

JJ on WHO: WHO said early on that aerosol transmission is misinformation. Now they’re trying to save face.

Governments find it convenient to push droplet route — if you are careless about droplets, it’s your fault. However, aerosol transmission makes it incumbent upon institutions to clean the air.

Governments want COVID to go away because they don’t want to spend money on it.

12/23/2021: Aerosol transmission appeared on WHO site

Name it to tame it and to claim it. You must say clearly it’s airborne!

LF’s hospital implemented precautionary principle with SARS1 (says KF)

LF: when you see people with sepsis and you don’t know the source of the sepsis, you use a broad spectrum antibiotic to kill off all bacteria that may be causing infection. Only after blood cultures come back do you narrow the antibiotics. It’s now become very difficult to pivot to precautionary principle.

How often do CR box filters need to be replaced?

KP: 6 months according to Rosenthal. Usually when you get a lot of crap in the filters, they get replaced. But even after 1 month the filters look black and gross. But the filtration isn’t that affected when the filters look “gross”.

LF: kids are sometimes arranged facing each other. Can you make small CR boxes?

KP: Small ones can be made. Suction hoods can also be placed in classrooms, and filters. Some people are using UV to kill virus (upper room UV). But it won’t remove allergens, dander and other pollution

LF on cholera:

If you’re vaccinated against cholera, you still won’t try to drink contaminated water. So even if you’re vaccinated against COVID, you should still avoid breathing contaminated air.

Is it possible to prevent transmission between household members eg. With young children that can’t be isolated? Is infection inevitable?

JJ: not inevitable. Even with people who become hospitalized, people in proximity infected at rate of ~30%.

JJ: CR box use minimizes infection (in that situation)

LF: there will be information on how to set up a sick room with COVID and how to prevent infection with family member, on the POP BC blog.

Q: 30 kids are being allowed to run around in gym for 40 minutes with no ventilation, 5 without masks out of 30. What do you think?

JJ: If the ones running remove the masks, that is not a good idea. Like when people take off masks to talk in front of camera, that’s a bad idea because talking is when you generate most aerosols. So, when you're exercising, you should not take off mask because that's when you generate the most aerosols.

KP: when exercising, you both inhale more and exhale more. So not unmasking would also protect you during exercise.

LF: Canadian women’s hockey team did competition with N95s, if they can do it so can you

JJ: making it harder to breathe might make training more efficient actually.

Final remarks

LF: BC still not allowing HEPA filters in classrooms, probably because PH still thinks it’s spread through droplets.

Everyone agrees that there is no interference between HEPA filters and HVAC system.

KP: HEPA filters actually minimize stuff that falls onto surfaces.

JJ: an official in Spain was tasked with writing how HEPA filters don’t work, and reason was that the government didn’t want to spend $ on HEPA filters.

LF: Even parents are willing to donate HEPA filters to school. And even with CR boxes, cost is minimal

LF: Cost of being hospitalized in general ward with COVID is $23,000. You can buy more in prevention with $23k than spending it on a single patient.

LF: There is plenty of long term disability with COVID too, and more money will need to be spent on that.

KP: CR boxes more effective, cheaper than going through gallons of hand sanitizer.

You can look at http://www.cleanaircrew.org for more on CR boxes.

JJ: doctors and aerosol scientists need each other. We’re wasting a lot of money doing useless interventions and not asking experts

KP: last thought — this is a very fixable problem. You just need to filter the air to knock down the spread. Places that have embraced aerosol spread theory are doing much better.

LF: in 8/2020, Chief Scientific Advisor for Government of Canada put together a table of experts, including aerosol and building engineers. In 9/2020, their report basically summarized everything these 3 said today. Engineers don’t understand why aerosol spread is such a debate. Dr. Teresa Tam was one of first to wear N95. In BC, Bonnie Henry still wears cloth mask.

KP: And people still take masks off to speak! Ugh

Archived Briefings from Protect Our Province BC

A Protect Our Province BC panel discussion with A panel discussion about how we as a community can pull together to create a safer learning environment for kids when school starts again in September! We can avoid another ‘tripledemic’ if we work together! Ready for Fall 2023? video: Briefing video:
“COVID-19 vaccination is safe during pregnancy and may protect newborns from infection, especially if vaccines are given in the second or third trimester. This is similar to what we are already doing with other maternal vaccines, including TDaP and seasonal influenza.” – Dr. Eastabrook
“If we had an epidemic of people with broken limbs and we saw people in plasters and crutches, it would be more evident. But there is a lot of disability that is happening, which is a hidden disability often, which is why we need to talk about it more, for people to understand what the consequences are. And that will help to make better decisions.” - Lynette

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