Science already knew that the presence of carbon dioxide in the air is harmful to human health. But the concentration of CO2 in the atmosphere can also prolong the life of viruses that spread through droplets in the air — such as SARS-CoV-2 (from Covid-19) — it’s new.
This is what a new study published in the journal Nature Communications. According to research, CO2 causes the virus to survive longer in the air and thus increases the risk of transmission.
“We knew that SARS-CoV-2, like other viruses, spreads through the air we breathe. But this study represents a major breakthrough in our understanding of exactly how and why this happens, and, crucially, what can be done to stop it,” explains Allen Haddrell, lead author of the study.
Understand the research
For the study, the researchers developed a bioaerosol technology called CELEBS (Controlled Electrodynamic Levitation and Extraction of Bioaerosols on a Substrate). The methodology allowed scientists to measure the survival of different variants of SARS-CoV-2 in laboratory-generated aerosol particles. In practice, it imitates the aerosol exhaled in the air.
So they carried out experiments varying the concentration of CO2 in the air between 400 parts per million, which is the normal level in open air, and 6,500 ppm. ANDIn a simulated CO2 concentration of three thousand ppm, for example, 10 times more viruses remained infectious after 40 minutes compared to clean air.
For now, climate projections indicate that the concentration of CO2 in the atmosphere is expected to exceed 700 ppm by the end of the century. Therefore, for Haddrell, the study helps to understand the reason for supertransmission episodes of Covid-19 happen in certain circumstances.
“The elevated pH of exhaled droplets containing the SARS-CoV-2 virus is probably one of the main factors in the loss of infectivity. CO2 behaves like an acid when it interacts with droplets. This causes the pH of the droplets to become less alkaline, resulting in the inactivation of the virus in them at a slower rate”, he explains.
Furthermore, the researchers also found that different variants of SARS-CoV-2 had different aerostabilities. In general, the last Ômicron variant had an extended useful life.
Advancement in science
For the study authors, the findings about CO2 pollution have implications for understanding the transmission of Covid-19 and other respiratory viruses.
“It shows that opening a window can be more powerful than originally thought, especially in crowded and poorly ventilated rooms, as the fresh air will have a lower concentration of CO2, causing the virus to be inactivated much faster”, comments Haddrell .
But they believe the research is broader and helps understand how changes in the environment could increase the likelihood of future pandemics.
