Lessons on Managing Indoor Air Pathogens

Lessons on Managing Indoor Air Pathogens

Late last week, the National Academies of Sciences, Engineering and Medicine (the NASEM) held a workshop on the indoor air management of airborne pathogens. Throughout this workshop, a range of experts shared lessons, practices, and innovations gained and learnt over the past couple of years living with COVID-19. 

If you’re interested in everything covered throughout the workshop, Alex Huffman created a fantastic Thread Reader here. You can find everything covered in the workshop in a single Twitter thread for easy reading on this page. We highly recommend checking out the link if you’re interested in indoor air management.

Although much was covered in the workshop, we want to focus on the discussions centring around masking and ventilation. These are the most applicable to our readers and what we believe most readers will be interested in.

One of the first findings presented was from a study conducted across 123 elementary schools with differing COVID prevention strategies. The study compared schools using different forms of air management. Some schools relied upon air dilution only, while others mixed air filtration and purification, and the last group used all three methods (dilution, filtration and purification).

Even the least effective ventilation (dilution only) decreased cases per 500 students from 4.19 (schools with no ventilation) to 2.94. This number was further decreased when filtration and purification were used (2.46) and all three methods (2.22). These findings show that while any air ventilation is an improvement over none, a combination of air dilution, filtration and purification is the best method for preventing the spread of COVID-19 in schools.

To further lower the cases per 500 students, masks and other techniques can be used. For the overall best strategy, scientists recommend a solid air ventilation strategy combined with mandatory mask wearing.

Andy Persily then dived into detail about how CO2 can be a useful proxy for identifying the COVID-19 risk in a situation. Studies have already shown that a doubling in CO2 concentrations represents a doubling in the chances of catching COVID-19 in a given indoor environment; however, the workshop went into more detail.

The speakers discussed that while CO2 is a good way to monitor COVID-19 risk, the CO2 concentration number alone isn’t the whole story. Rather than considering just the concentration in isolation, we need to consider the context in the room. For example, how many people are in the room plays a vital role in the risk factor of catching COVID-19.


If you’re interested in monitoring CO2 levels and seeing how they impact your health, you might be interested in checking out this article on carbon dioxide and how it acts as a proxy for COVID-19 risk. If you want to read more about this workshop, you can do so here.

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