The more CO₂, the faster the virus spreads

A new study shows that keeping CO₂ levels low helps reduce the infectious viral load in the air.

According to chemist Allen Haddrell from the University of Bristol (UK), opening windows can have more significant effects than people think, especially in crowded and poorly ventilated rooms. Fresh air will have lower CO2 concentrations _, inactivating the virus much faster.

_{CO 2} concentration  affects the virus

By measuring the ability of SARS-CoV-2 to maintain infectivity when aerosolized in droplets, under different environmental conditions, Haddrell and colleagues detected that CO ₂ concentrations in the air affect directly affects the stability of the virus.

Fresh air will have lower CO2 concentrations, making the virus inactivated much faster - (Photo: UKRI)

They used a new technique to measure the effects of different temperatures, relative humidity and gas concentrations on suspended virus particles. Atmospheric CO ₂ concentrations have been measured at about 400 parts per million (ppm).

However, when enough people gather in a closed room, the concentration can spike to about 3,000 ppm. The team found that the number of infectious virus particles at this high concentration could be 10 times higher than the amount of virus that could be found in outdoor air.

"The high pH of exhaled droplets containing SARS-CoV-2 virus may be the main cause of loss of infectivity.

CO ₂ acts as an acid when interacting with water droplets. This causes the pH of the water droplets to become less alkaline, resulting in the virus inside them being inactivated at a slower rate ," Haddrell explains.

Furthermore, crowded environments in poorly ventilated spaces can exceed 5,000 ppm CO ₂ . This relationship sheds light on why super-spreading events can occur under certain conditions, noted chemist Haddrell.

Climate change increases the spread of viruses

Different strains of SARS-CoV-2 have different stability profiles in the air. So, although more research is needed to confirm the relationship between CO2 _and other viruses, researchers suspect this difference may explain why many respiratory viruses have different properties. seasonal quality.

When the weather is colder, people tend to spend more time indoors and are more exposed to air with higher concentrations of CO _{2 .} The amount of CO ₂ in outdoor air is also increasing due to global warming. Recent forecasts predict concentrations could exceed 700 ppm by the end of the century.

"The study also highlights the importance of the global net zero target, showing that even modest increases in CO ₂ levels , and capital gains due to climate change, can significantly improve the virus survival rate and increase the risk of the virus spreading ," Haddrell added.

Physical chemist Jonathan Reid, from the University of Bristol, concluded: "These findings could serve as a scientific basis for designing risk mitigation strategies, to save lives in the future." any future pandemic".

The research was published in the journal Nature Communications.

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