British Columbians who've kept abreast of research about the transmission of COVID-19 share a common frustration.

They're exasperated that the B.C. NDP and B.C. Liberal caucuses have not shown any nerve in taking on a bunch of well-educated people at health authorities and the Provincial Health Office who've downplayed the primacy of airborne transmission of COVID-19.

These British Columbians are thrilled that B.C. Green Leader Sonia Furstenau has demonstrated considerable curiosity about this topic. Here's an excerpt from her recent statement about COVID-19.

"Government should invest in improving public HVAC systems and making portable air filtration devices with HEPA filters widely available," the B.C. Green leader declared.

"We need to see CO2 monitors in every classroom and health facility space. With the recognition that COVID-19 is airborne, we must also recognize the need for high-quality, well-fitting masks," she continued. "N95 and equivalent type masks, which are especially crucial in crowded, indoor spaces, should be available at no cost."

In addition, Furstenau stated that the province can help by rapidly expanding public education about the risks of airborne COVID-19 transmission.

This has led some traditionally NDP-leaning voters to eagerly embrace the B.C. Greens.

These British Columbians believe that the reluctance of B.C. NDP and B.C. Liberal politicians to speak up is a key reason why there have been more than 4,000 official deaths linked to COVID-19. There are quite likely many thousands more that are not included in these statistics.

School trustees, union executives, the TransLink Mayors' Council, B.C. Ferries directors, and board members for colleges and universities have also gone along with the well-educated health officials.

Some of these health officials even signed a 2020 letter published in Clinical Infectious Diseases disputing that COVID-19 was primarily being transmitted via the airborne route.

As K-12 students are about to return to classrooms and thousands of university students move into dormitories, there are growing fears of a new wave of COVID-19 because of the lack of a provincewide indoor mask mandate and the lack of public education about airborne transmission.

With that in mind, I'm sharing the results of three studies published this year in peer-reviewed journals.

I'm doing this with the objective of offering some guidance to parents, students, and workers who've lost faith in public-health officials' ability to keep us safe.

If the B.C. NDP government isn't going to listen to Furstenau's recommendation to elevate public understanding about airborne transmission of COVID-19, then it's up to the media to fill this void.

1. SARS-CoV-2 aerosol transmission in schools: the effectiveness of different interventions

This paper was published in the Swiss Medical Weekly in May and relied on the COVID Airborne Risk Assessment (CARA) tool. It was developed at the European Organization for Nuclear Research, a.k.a. CERN.

The researchers assessed the impact of different interventions on the concentration of virus particles in a 160-square-metre classroom with one occupant infected with COVID-19.

"CARA uses a physical model developed to simulate the concentration of virus particles in an enclosed indoor volume," the researchers wrote. "Based on this, the cumulative dose of virions absorbed by exposed occupants is calculated, which could be used to predict the probability of on-site transmission."

The researchers then decided to test the impact of open windows on the concentration of the virus. The opening width was set to 60 centimetres for fully open or 20 centimetres for partially open.

"School days were divided into eight periods of 45 minutes with a 60-minute lunch break in the middle of the day and two 30-minute yard breaks (one in the morning and one in the afternoon)," they noted. "The occupants of the classroom were assumed to remain the same throughout the day and to leave the class during lunch and yard breaks. Since natural ventilation is influenced by the difference between indoor and outdoor temperatures, we simulated two different seasons: spring/summer—with an outdoor temperature of 18°C—and winter—with an outdoor temperature of 5°C.

In both scenarios, indoor temperatures were set at 22°C and the relative humidity was at 50 percent in summer and 30 percent in winter.

"In the absence of interventions, the cumulative dose absorbed was 1.5 times higher in winter than in spring/summer, increasing chances of indoor airborne transmission in winter," the researchers concluded. "However, natural ventilation was more effective in winter, leading to up to a 20-fold decrease in cumulative dose when six windows were fully open at all times. In winter, partly opening two windows all day or fully opening six windows at the end of each class was effective as well (2.7- to 3-fold decrease)."

Opening windows all day in summer with students present led to a two-to-seven-fold decrease in virus concentrations, depending on the number of windows. However, there was a "minimal effect" from opening windows during yard and lunch breaks.

Other steps were taken to measure the effectiveness of HEPA filters and face masks.

"One HEPA filter was as effective as two windows partly open all day in winter (3-fold decrease) whereas two filters were more effective (5-fold decrease)," the researchers concluded. "Surgical face masks were very effective independently of the season (8-fold decrease).

"Combined interventions (i.e., natural ventilation, masks, and HEPA filtration) were the most effective (≥25-fold decrease) and remained highly effective in the presence of a super-spreader."

https://twitter.com/DrFiliatrault/status/1566344231220019200

2. The Dynamics of SARS-CoV-2 Infectivity with Changes in Aerosol Microenvironment 

This study by researchers at the University of Bristol looked at the airborne survival of viruses such as SARS-CoV-2 in tiny aerosols (five to 10 microns in radius), which are expelled from humans when they breathe, talk, sing, and cough.

They used a "novel instrument" to determine that the infectivity of the virus declined by 90 percent within 20 minutes of becoming airborne. However, there's a catch—most measurements were conducted with SARS-CoV-2 virus isolated early in the pandemic.

The tests involved the alpha variant and a mutant isolated in England in 2020 with the same spike protein sequence. However, the researchers wrote that there is no reason to believe that the measurements in their study "are not representative of later circulating variants of the virus".

Moreover, if an infectious people remain in a room, they will be continuing to replenish the air with the virus.

The study was published in the Proceedings of the National Academy of Sciences.

"Elevation of CO2 levels within a room is taken as a clear sign of occupancy and poor ventilation," the researchers wrote. "There has been increasing discussion surrounding the use of CO2 monitors as a means of determining the relative risk of COVID-19 transmission in various settings.

"The data from this study give further credence to this approach," they continued. "Not only is elevated CO2 an indication of a densely occupied, poorly ventilated space, but it could also be indicative of an environment in which SARS-CoV-2 is more stable in the air." 

The researchers wrote that "CO2 monitors may present an immensely valuable means of assessing the relative risk of different indoor environments". 

It's worth noting that the B.C. government has refused to pay for CO2 monitors in classrooms, despite requests to do so from Safe Schools Coalition B.C.

3. Practical Indicators for Risk of Airborne Transmission in Shared Indoor Environments and Their Application to COVID-19 Outbreaks

This study was published in Environmental Science & Technology and focused on key factors that influence the transmission of airborne diseases.

These factors included the rate of aerosol generation, breathing flow rate, masking and its quality, ventilation and aerosol-removal rates, and the number of occupants and duration of exposure.

"It is widely accepted that measles, tuberculosis, and chickenpox are transmitted in this way, and acceptance is growing that this is a major and potentially the dominant transmission mode of COVID-19," the researchers wrote. "There is substantial evidence that smallpox, influenza, SARS, MERS, and rhinovirus are also transmitted via inhalation of aerosols."

They examined short-range airborne transmission with overlapping breathing zones, shared-room airborne transmission, and not sharing a room or being far apart in the same room in what's known as "longer-distance airborne transmission".

"Measles outbreaks occur at much lower risk parameter values than COVID-19, while tuberculosis outbreaks are observed at higher risk parameter values," the researchers stated. "Because both diseases are accepted as airborne, the fact that COVID-19 is less contagious than measles does not rule out airborne transmission."

COVID-19 was described as a "pathogen of initially moderate infectivity (more recently increased by some variants such as Delta or Omicron)". The paper documented outbreaks of COVID-19 in choir rehearsals, religious services, buses, workshop rooms, restaurants, and gyms.

"There are a few documented cases of longer-distance transmissions of SARS-CoV-2 in buildings," the researchers wrote. "However, cases of longer-distance transmission are harder to detect as they require contact tracing teams to have sufficient data to connect cases together and rule out infection elsewhere."

They concluded that most indoor spaces require mitigation measures to curb what they call shared-room airborne transmission.

"Among effective measures are reducing vocalization, avoiding intense physical activities, shortening the duration of occupancy, reducing the number of occupants, wearing high-quality well-fitting masks, increasing ventilation, improving ventilation effectiveness, and applying additional virus removal measures (such as HEPA filtration and UVGI disinfection)," they stated.

Groups call on province to follow the science

The B.C. government has spurned requests from Safe Schools Coalition B.C. and other groups for HEPA filters in classrooms .

The NDP cabinet has also rejected the groups' demands for universal masking with KN95 or better models, and ventilation in classrooms that meets guidelines set by the American Society of Heating, Refrigerating and Air-Conditioning Engineers Task Force.

"It is long past time for the government of British Columbia and BC Public Health leadership to start following the best available science to protect the residents of BC, especially our youngest and most vulnerable," the groups stated in a recent open letter to Health Minister Adrian Dix and Education Minister Jennifer Whiteside.

"Our children should not be repeatedly exposed to and infected with a novel virus. Avoiding COVID-19 infection is the best way to ensure a future full of potential and free from (further) disability for all our children," they continued.

"The BC government must accept the reality of how COVID-19 spreads through aerosols; the reality that children do get infected and in turn infect their families and communities; the reality that our schools are presently ill-prepared to prevent the spread of this infection; and the reality that COVID-19, a novel virus, and can harm our children."