New research suggests that keeping CO2 levels low can reduce infectious airborne viral loads, particularly in spaces with limited ventilation. The study, focused on the pathogen behind COVID-19, highlights the importance of maintaining low CO2 concentrations to minimize the risk of virus transmission. According to University of Bristol chemist Allen Haddrell, opening a window in crowded and poorly ventilated rooms may be more effective than previously believed. Fresh air with lower CO2 concentrations can lead to faster inactivation of the virus, making it less likely to spread.
Haddrell and his colleagues utilized a novel technique called Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto a Substrate (CELEBS) to study the impact of environmental conditions on the stability of SARS-CoV-2. By examining how temperature, relative humidity, and CO2 concentrations affect virus particles suspended in the air, the researchers found that CO2 levels directly influence viral infectivity. The current atmospheric CO2 concentration stands at around 400 parts per million (ppm), but in crowded indoor spaces, this can escalate to 3,000 ppm or even exceed 5,000 ppm in poorly ventilated environments.
The high pH of exhaled droplets containing SARS-CoV-2 plays a crucial role in reducing the virus’s infectiousness. CO2 acts as an acid when it comes into contact with droplets, causing their pH to become less alkaline and slowing down the inactivation of the virus. This explains why virus particles can remain infectious for longer periods in environments with elevated CO2 levels, potentially leading to super-spreader events under specific conditions. Moreover, different strains of the virus exhibit varying patterns of stability in the air, with Omicron (BA.2) showing higher viable viral particle concentrations than the Delta variant after just 5 minutes.
While further research is needed to understand the relationship between CO2 levels and other types of viruses, the findings suggest a potential explanation for the seasonality of many respiratory infections. As people spend more time indoors during colder weather, they are exposed to higher levels of CO2 in the air, which can enhance virus survival. With global warming contributing to the increasing concentration of CO2 in outdoor air, projections indicate that levels could surpass 700 ppm by the end of the century. This underscores the importance of global net zero goals in combating climate change and reducing the risk of virus spread.
The study underscores the critical role of CO2 levels in shaping infectious airborne viral loads and highlights the need for mitigation strategies to prevent future pandemics. By understanding how environmental factors such as CO2 concentrations affect virus stability, researchers can develop interventions to minimize the risk of transmission and save lives. The implications of this research extend beyond the current COVID-19 pandemic, offering valuable insights into the dynamics of virus spread and the impact of climate change on infectious diseases.
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