Recent research has suggested that keeping CO2 levels low can assist in reducing infectious airborne viral loads, particularly in spaces with limited ventilation. This study, which primarily focused on the pathogen responsible for COVID-19, has extensive implications for decreasing the risk of virus transmission. According to University of Bristol chemist Allen Haddrell, “Opening a window may be more powerful than originally thought,” especially in crowded and poorly ventilated rooms where fresh air with lower CO2 concentration can cause the virus to become inactivated more rapidly.
Haddrell and his team conducted the study by measuring SARS-CoV-2’s capacity to remain infectious while aerosolized in droplets under various environmental conditions. They utilized a novel technique called Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto a Substrate (CELEBS) to measure the impact of temperature, relative humidity, and different gas concentrations on suspended virus particles. The study found that atmospheric CO2 concentrations are typically around 400 parts per million (ppm), but in closed rooms with a high number of individuals, concentrations can reach up to 3,000 ppm.
In environments with high crowd density and poor ventilation, CO2 levels can exceed 5,000 ppm. This correlation sheds light on why super spreader events may occur under certain circumstances. Additionally, the study revealed that different strains of SARS-CoV-2 exhibit varied patterns of stability in the air. For example, after just 5 minutes, viable viral particle concentrations for the Omicron (BA.2) strain were 1.7 times higher than for the Delta strain, suggesting significant variability between viral particle types.
While further research is necessary to confirm the relationships between CO2 and other viruses, the initial findings suggest a potential explanation for the seasonality of many respiratory viruses. Colder weather often leads to increased indoor activities, exposing individuals to higher CO2 levels in the air. Moreover, the outdoor air’s CO2 concentration is escalating due to global warming projections anticipate concentrations to surpass 700 ppm by the end of the century.
The study underscores the criticality of global net zero goals, as even slight elevations in CO2 levels can significantly enhance virus survival rates and the risk of transmission. These findings provide a scientific foundation for designing mitigation strategies that could potentially save lives in future pandemics. University of Bristol physical chemist Jonathan Reid emphasizes the importance of this research for developing effective public health interventions.
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