Research has shown that keeping CO2 levels low can have a significant impact on reducing infectious airborne viral loads. While the focus of the study was on the virus behind COVID-19, the implications extend to reducing the transmission risk of various viruses in spaces with limited ventilation. According to University of Bristol chemist Allen Haddrell, simply opening a window can be more effective than originally believed. In crowded and poorly ventilated rooms, fresh air with lower CO2 concentrations can lead to faster inactivation of viruses.
By utilizing a new technique called Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto a Substrate (CELEBS), researchers were able to measure how environmental conditions impact the stability of the SARS-CoV-2 virus. The study found that CO2 levels in the air directly affect the virus’s ability to remain infectious while aerosolized in droplets. In indoor environments where CO2 concentrations can reach as high as 3,000 ppm due to overcrowding, the number of viral particles capable of remaining infectious can be ten times higher than in outdoor air.
The high pH of exhaled droplets containing the SARS-CoV-2 virus plays a crucial role in the loss of infectiousness. CO2 acts as an acid when interacting with droplets, causing the pH to become less alkaline and resulting in slower inactivation of the virus. In settings with CO2 concentrations exceeding 5,000 ppm, the risk of super spreader events significantly increases. Furthermore, different strains of SARS-CoV-2 exhibit varying patterns of stability in the air, with Omicron (BA.2) showing higher viable viral particle concentrations after 5 minutes compared to Delta.
While more research is needed to fully understand the relationship between CO2 levels and other viruses, there is evidence to suggest that the seasonality of respiratory viruses may be influenced by CO2 concentrations. As people spend more time indoors during colder weather, they are exposed to higher levels of CO2, which can impact virus survival rates. Additionally, with global warming leading to an increase in outdoor CO2 levels, projections indicate that concentrations could exceed 700 ppm by the end of the century. This highlights the importance of global net zero goals in combatting climate change and reducing the risk of virus spread.
The findings from this research serve as a critical foundation for designing mitigation strategies to prevent the spread of viruses in future pandemics. By understanding the relationship between CO2 levels and viral loads, we can develop effective measures to protect public health and save lives.
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