Monitoring airborne transmission
My friend Bobby Julian had an offbeat agenda when he watched the Ateneo-La Salle basketball game last week. He went to the Araneta Coliseum to root for his team. However, his team lost, which obviously made him disappointed.
But he had another purpose in attending the game. He wanted to measure the air quality inside the Coliseum. Bobby was curious about how risky (or how safe) it was to be in an indoor arena together with a cheering, chanting, and jeering crowd.
A senior citizen, Bobby is most prudent to protect himself from COVID-19. In that regard, he is sensitive to indoor air quality.
The evidence is clear that airborne transmission is COVID-19’s main infection route. In this case, the social distancing rule of one meter or two meters to avoid infection no longer suffices. Particles from the infectious person can move throughout the indoor area and can linger in the air for even hours.
Here is Bobby’s narration:
“Now that I’ve overcome the grief from the loss, I can tell you what else I did. I brought my CO2 [carbon dioxide] monitor and measured the ppm [parts per million] at different times during the game. In brief:
“700-750 ppm before the start of the game. 1,400-1,450 ppm at halftime. 1600-1650 ppm at the end of the game. 1,750-1,800 ppm in the foyer after the game.”
Measuring the CO2 levels is a way to determine the risk of getting COVID-19. A high level of CO2 is an indicator of COVID-19 risk. Said another way, the lower the CO2 measured in terms of ppm, other things held constant, the lower the risk of getting COVID-19. A high level of indoor CO2 will hence require improving the room or building’s ventilation.
The risk is also relative to the specific setting — the space, the length of time, and the activity. For instance, at an initial CO2 level of 700 ppm, the risk is less for someone studying at the quiet and sparse Ateneo or La Salle library for an hour than for the same guy being at the noisy and packed Araneta Coliseum to watch a two-hour basketball game.
What do the CO2 ppm numbers that Bobby gave suggest? Outdoor air quality (or fresh air) is equivalent to a CO2 level of around 450 ppm. Under pandemic conditions, according to a paper published by Canada’s National Collaborating Center for Environmental Health (NCCEH), “we should seek to keep indoor air as close to ‘fresh’ outdoor conditions as possible, where outdoor air generally has a CO2 concentration <450 ppm.”
As it is unrealistic to have “fresh air” indoor, the recommendation from the Philippine Health Professionals Alliance against COVID-19 (HPAAC) is to have a CO2 level that won’t exceed 800 ppm. A CO2 level that exceeds the threshold level of 1,000 ppm is a yellow sign, a warning sign that air quality is deteriorating, thus increasing the risk of COVID-19 infection in a crowded area.
To be sure, CO2 levels ranging from 1,600 to 1,800 ppm after the end of the game suggest danger — a red sign that Araneta Coliseum must do remediation to improve air ventilation. As Bobby said, it is no longer enough for Araneta Coliseum to make a public announcement to remind the people to wash their hands and wear masks.
Having CO2 monitors is an essential feature towards improving ventilation and reducing COVID-19 risk. The persistence of COVID-19 and the increasing number of people getting long COVID, exacting a heavy toll on the nation’s health and productivity, compel us to take new measures beyond the conventional. Installing CO2 monitors or sensors in indoor places is a most practical approach. And like the wearing of mask, it is cost-effective.
Monitoring CO2 is a basic condition for the building owners to improve indoor air ventilation. Moreover, it enables the whole public to become acutely aware of airborne transmission as the primary mode of COVID-19 infection. It will make the public see the salience of following and sustaining risk-reduction behavior.
Thus, mandating private establishments and public offices to install CO2 monitors is a sensible policy. It has huge spillover effects that will transform our landscape towards pandemic resiliency.
Some countries have shown the way. The Netherlands has announced a policy of installing air-quality monitoring devices in all classrooms. The Dutch government will also give subsidies for schools that will be able to improve ventilation.
Belgium’s Council of Ministers has prepared and adopted a framework bill that, according to the Federal Public Service, will lay “the foundations for an ambitious policy dedicated to indoor air quality.” Among the bill’s features is defining the standards for CO2 monitors and purification installations. One standard is to have a CO2 concentration within premises that is below 900 ppm.
Bobby’s hope is that President Bongbong Marcos will immediately act on a policy that will enable the improvement of air ventilation. A low-hanging fruit is mandating the monitoring of CO2 levels. It is practical, effective, and affordable.
In fact, the groundwork for this already exists. The panel of reviewers from the University of the Philippines’ Institute of Clinical Epidemiology, in cooperation with the Philippine Society for Microbiology and Infectious Diseases, strongly recommends the use of CO2 monitors, which “could serve as a real-time guide to initiate activities that improve air ventilation (such as promoting distancing, opening windows, or turning on electric fans).”
Furthermore, the Department of Labor and Employment has a Department Order No. 224, series of 2021 that provides the guidelines on ventilation for workplaces and public transport. It is now a question of upgrading it toward having wider coverage and ensuring its national compliance. Perhaps this can be done through an Executive Order or legislation.
To reiterate, Bobby would like the President to do something concrete about improving air ventilation. A pronouncement from the President could nudge Araneta Coliseum to address its air quality. That will motivate Bobby to watch the return match between Ateneo and La Salle.
Who knows, a safe Araneta Coliseum might even entice President Bongbong to watch the game, too. Especially at the time of COVID-19, a place where rivals meet, but likewise a place with good air quality, is a healthy place where everyone belongs.
Filomeno S. Sta. Ana III coordinates the Action for Economic Reforms.
