CO2 as a Proxy for Covid-19 Airborne Infection Risk

Fresh Air is Our Best Friend in 2020/21

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Carbon Dioxide or CO2 is naturally exhaled as we breathe and increased CO2 concentration is a useful proxy for exhaled water vapour. The greater the exhaled CO2 concentration, the great the exhaled water vapour concentration and this is where the transmission risk of SARS Covid 19, increases.

Water vapour traps the virus (when exhaled) and is suspended in the air, this is not an issue outside, but when the air is trapped inside and has nowhere to go (due to lack of air movement and or poor ventilation) the density of water vapour invisibly builds and increases the risk of cross spread infection. Water vapour can therefore be measured (indicatively) by the level of CO2 in the air and the risk factor assessed by our CO2 measurement equipment.

The German Environment Ministry* has published guidance that concentrations of CO2 over 1000ppm in schools, offices and enclosed spaces is a sign of increased risk of transmission and the need for through flow of fresh air. There are however spaces where people will be exhaling greater quantities of CO2 and indeed drawing in deeper breaths as their body is under strain, an example of this is a gym.

EMCO Sentinel equipment can be set to alert at 1000ppm or even below if preferred, so that there is time for air flow to take effect. The device indicates the level of CO2 in the air constantly, so that varied air flow & ventilation solutions can be evaluated. A digital readout linked to an audible arm or visual alarm then provides an objective and repeatable level to building and venue owners, who can then ensure sufficient ventilation to protect their employees and customers.

Establishing the level of CO2 is only part of the story, using and monitoring this data to build workable models for using spaces brings the opportunity to consider a more micro level. Through flow of air is vital to changing the air inside a building and thus simply opening the window may not be enough and whilst the occupant of a room next to the window may get cold and close it quickly, in reality without a draft from air moving in and out of a room the atmosphere may not be changed. EMCO Sentinel equipment is able to guide users by showing CO2 levels during testing, to ascertain the best method of ventilation and helping to identify genuine workable options.

With fresh air "one of our best friends in 2020", making sure there is an adequate supply in winter is vitally important. Using CO2 as a proxy monitor of air quality will act as a reminder that increased exhaled water vapour can increase the spread Covid-19 and therefore keeping the windows shut and the heat ON, may not always be the safest solution. It is hoped that establishing this information at a space by space level ,can allow buildings, institutions and companies to stay open, stay safe and see the winter through.

Find out more about EMCO Sentinel CO2 Instruments

References

German Environment Ministry

*https://www.umweltbundesamt.de/sites/default/files/medien/2546/dokumente/irk_stellungnahme_lueften_sars-cov-2_0.pdf

Harvard T H Chan School of Public Health

https://schools.forhealth.org/wp-content/uploads/sites/19/2020/06/Harvard-Healthy-Buildings-Program-Schools-For-Health-Reopening-Covid19-June2020.pdf

Peng & Jimenez University of Colorado

https://www.medrxiv.org/content/10.1101/2020.09.09.20191676v1.full.pdf

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