What do we know about indoor air quality?

Man wearing mask, pouring a hot drink

As part of our work here at AirQ we’ve been measuring air quality at locations around Toronto, we’ve done so at nearly 400 unique locations including restaurants, cafés, retail stores, banks, grocery stores and more. Doing so helps us build our understanding of how air quality is affected by various elements including location size, access to the outdoors, presence of ventilation systems and more. And given the Government of Ontario has set different rules for these different types of establishments, collecting data on air quality in each helps us understand whether we’re aiming correctly from a policy perspective. This policy-lens is perhaps most important when it comes to the restaurants and small businesses that have been forced to close, or open at vastly reduced occupancies.

So what does the data tell us so far?

Before we get to that, let me add two caveats. First, while we have close to 400 locations in our sample, the breakdown by location-type means that in some cases we’re inferring from a dozen or two samples in a location-type, far from ideal to make generalizations. Second, we are unable to control for occupancy in each location measured. That said, given relatively standard lockdown-inspired occupancy limitations across the GTA, we’re comfortable using this data as a representation of a near-baseline for each location type. And ultimately, we present the following to illustrate the value of capturing air quality data and to underline the need to do more research like this.

What do we know so far?

1. 99% of the restaurants measured have “low-risk” air safety (under 800 ppm CO2). As you can read in our Restaurant Case Study available here, the presence of exhaust fans in restaurant kitchens provide a tremendous amount of air ventilation. The risk of getting infected here, assuming the average incidence rate across Toronto (and occupancy restrictions), is less than .01 percent;

2. Retail stores located in interior malls show higher air safety risks than do retail establishments with exterior/outdoor access. This difference holds for size of retail establishment, with over 50% of both small and large exterior-retail scoring as very low risk (under 600 ppm) compared to just 18% for in-mall retail;

3. If one activity has remained constant for most of us over the past 10 months it’s grocery shopping. Yet, and I’ll repeat the caveat about small sample size, it would seem that grocery stores are on the wrong side of our air safety measurements. In fact, nearly three quarters of our sample of grocery stores measured in our “some-risk” category of between 800 and 1200 ppm. While this doesn’t mean these locations are unsafe, it does mean that air quality and air ventilation in these locations present a higher level of risk than other establishments.

What can we take from all this?

First, given the absence of granular data on where infections are being transmitted, the frustrations of small business owners and restaurateurs are quite rational. Given the steps they’ve taken to create safe physical spaces, and the fact that 99% have air flow that qualifies as low-risk, the decision to shut down all indoor dining could be seen as an over-reaction. What we should want is for every indoor dining room to have an air quality meter that provides a risk score for staff and customers. This would allow the problematic 1% to know they have a problem and move towards rectifying it.

Second, the decision made to allow big-box stores and grocery stores to remain open for regular shopping while small and medium-sized retail is limited to curbside also defies the data shown here and again makes the frustrations of Ontario’s small business community quite logical. Air quality in small and medium sized shops is, on average, no different than large retail and far better than in grocery stores. If stores were able to measure their air quality and base occupancy on real-time data relevant to their location as opposed to standardized percentages, then both staff and customers could shop in any establishment with far more comfort.

Third, you can’t manage what you don’t measure. Policy makers and business owners are flying blind as to the real risks of Covid transmission. We’ve spent 10 months worrying about physical distancing but have neglected to focus on aerosol transmission. While staying home is indeed the only fail-proof way to ensure zero risk, finding a balance that allows businesses to open and for staff and consumers to enter those spaces confident that their risk is low, requires a measurement of air quality risk. Doing so should follow the lead of other jurisdictions and see air quality monitors become as commonplace as smart thermometers in all businesses and schools. The cost of this technology is negligible given the peace of mind and data-driven targeted problem solving it will allow.

Ultimately, while we’ve been led to believe that the only choice we have is a trade-off between health and economics, a more nuanced view would use data to determine where elevated risk lies and allow for targeted interventions as opposed to the broad shutdowns employed so far.

Here at AirQ we’re committed to helping both business and government find this path forward. If you’re interested in chatting, please get in touch.



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