If a waiter at a restaurant brought you a murky, stinky glass of water, that would be unacceptable. But yet, many waiters — at least before the Covid-19 pandemic hit — were forced to breathe poorly ventilated air in restaurants and other indoor spaces where people packed together.
And still today, “if anybody asks a restaurant owner, ‘what’s the ventilation here?’ they will probably look strangely at them,” says Lidia Morawska, a physicist and an aerosol expert at the Queensland University of Technology in Australia who has advised the World Health Organization on the spread of airborne pathogens.
In the post-pandemic world, Morawska wants all of us to ask the question — “what’s the ventilation like in here?” — more often. And not just of restaurant owners, but of the managers of the crowded indoor spaces we visit. We should expect to breathe in clean, virus-free air just like we should expect to get clean water in a glass. And it’s not just up to individuals to demand better air quality — governments and engineering associations need to set new standards to ensure clean air for all.
The pandemic has made clear we can be infected with respiratory viruses more easily in poorly ventilated spaces, where the virus people are breathing out of their nose and mouth can linger in the air longer. Ventilation works by either replacing stale, potentially infectious air with fresh clean outdoor, or passing that stale air through a filter.
Earlier in the pandemic, Morawska led a group of air quality experts who asked the WHO to recognize that the coronavirus can spread in aerosols across long distances (as opposed to just occurring in close contact situations of 6 feet or less). Eventually, the WHO and US Centers for Disease Control and Prevention recognized this more explicitly in their scientific guidance.
But when the pandemic is over, we’ll still need better ventilation to prevent future outbreaks of respiratory diseases including coronaviruses, but also the cold and flu.
Last week, Morawska and a few dozen other air quality experts put out a manifesto of sorts in Science,calling for “a paradigm shift to combat indoor respiratory infection.”
“Governments have for decades promulgated a large amount of legislation and invested heavily in food safety, sanitation, and drinking water for public health purposes,” Morawska and her co-authors write. “By contrast, airborne pathogens and respiratory infections, whether seasonal influenza or Covid-19, are addressed fairly weakly, if at all, in terms of regulations, standards, and building design and operation, pertaining to the air we breathe.”
Recently, I spoke with Morawska about what the public needs to know about indoor air and how we can use carbon dioxide monitors to quickly determine ventilation quality in a space. Our conversation has been edited for length and clarity.
You and your co-authors write there needs to be a “paradigm shift” in how we think about ventilation in infection prevention. What’s the shift?
We compare the shift in thinking, and action, in relation to clean water. There was no clean water [standard] before a 19th-century movement started. People accepted that water could be contaminated, or they could get sick drinking water.
So there was a paradigm shift. This is the same thinking: We don’t have to accept that we get sick due to respiratory [viruses that spread easily in poorly ventilated indoor air]. We should do something about it.
So we now have a centralized system for cleaning water and taking pathogens out of it: treatment plants, distribution. For air, there’s no centralized system for distributing it in a community the way there is for clean water. Is this problem a lot harder than water quality?
It is harder, but it’s not unresolvable.
With water, the point is if water was contaminated, and then you get sick quickly after [drinking it], the whole neighborhood would make a big fuss about it. But you don’t know if the air in the building is contaminated or not. If you come down with a cold or flu three, four days later, you don’t know whether you contracted it in the building.
So how could we do better in making sure air in indoor spaces isn’t contaminated?
We don’t really need to come up with some new technologies. We just need to use them. The simplest (though perhaps over-simplistic) would be a display of CO2 concentration. [Either via handheld CO2 monitors or CO2 monitors mounted in a public, visible space.]
And CO2 concentration would tell you that there’s a lot of people breathing in this room and what they’re exhaling isn’t being cleared out very quickly?
There are standards for CO2 concentrations, though in many buildings no one checks. But if it was mandated [to display CO2 concentrations in an indoor space] individuals could see the ventilation is bad.
I would imagine there would have to be a lot of education to do there. I don’t have an intuitive sense of what a high CO2 concentration is. And it might be confusing, because CO2 is a few steps removed from the thing you actually want to know which is: Is this air contaminated?
This technology has been used in Europe particularly in Germany for at least 10 years if not longer, in schools. It’s not just a CO2 meter, it also has this traffic light system: green, yellow, and red. The students and the teachers don’t have to look at what the concentration is, they see the color.
And if you saw red, you’d open a window or something.
Yeah, you’d know there is a problem. But in places where there are no windows, either you leave, or go to the manager, boss, or whoever and say “there’s something wrong here.”
[Right now,] if anybody asks a restaurant owner, “what’s the ventilation here?” they will probably look strangely at them. So this question needs to be asked at all levels and in particular with the government.
If we address air quality, we would have fewer sick days?
If there’s a lower probability of infections, there will be fewer infections. There’s no reason why it wouldn’t [work].
On the most basic level, what should be the standard for ventilation in indoor spaces when it comes to preventing infections?
The most important thing is the purpose of the standard. If you read the purpose of the ASHRAE standards [The American Society of Heating, Refrigerating and Air-Conditioning Engineers, which writes standards for building ventilation systems], the purpose doesn’t include infection prevention. So the most important one is simply, include infection prevention in the purpose of the standard.
There are already existing standards and ventilation guidelines, but none of them take into consideration infection transmission. So this has to be added.
Does any country currently recognize this in their indoor air quality standards?
Working with a very large group of colleagues from around the world, no one has ever said that ‘in our country, buildings are designed to take care of this.’ We can confidently say this is not taken into account anywhere.
So how do the standards change?
One way is to be prescriptive: saying each space requires this many [air] exchanges [exchanges meaning completely replacing the air in the room with fresh air], or this many liters per person per second. And there are already some recommendations or ideas about this.
But there are also tools for risk assessment that consider the specifics of the environment in terms of the number of people and in terms of the activities conducted there. This is important, because when we are sitting and quietly breathing in a library, we exhale significantly less than if we are talking or singing.
There won’t be one specific value for a gym because gyms vary in terms of size and number of people.
It will cost money to implement this.
It will cost money in an initial investment, but as we try to assess the cost, this would be incomparably small to the cost of infection.
Would there be downsides to these higher standards? I understand that if you’re bringing in more outside air to a building to ventilate it, you need to use more energy to heat or cool that air. Is there some acknowledgment that increasing ventilation and addressing these problems might also lead to more energy use?
If we were just taking the fresh air, outdoor air — that has to be treated to be cooled down or heated up depending on the climate. This will significantly increase energy consumption. But sometimes there are hybrid systems that use natural ventilation and mechanical ventilation.
The [already heated or cooled] air can still be recirculated. It has to be properly filtered to remove the contaminants [i.e. viruses] so effectively we’re bringing back to the room the same air, but you are cleaning it.
Would it be a shame if we don’t use the pandemic as an instigator to make some of these changes?
It would be more than a shame, I’d say it would be a tragedy. We don’t know how many lives could have been saved if there were proper ventilation systems in the buildings now.