CO2 hazard mapping in the buildings of La Bombilla and Puerto Naos (La Palma, Canary Islands) using of alkaline traps

Carbon dioxide (CO₂) is a gas that is found in small amounts in Earth's atmosphere. It is released into the atmosphere by volcanoes, but it is typically diluted to low concentrations very quickly and is not harmful to people or animals. However, in certain stable atmospheric conditions, cold CO₂ gas can flow into low-lying areas and reach higher concentrations. At these concentrations, CO₂ can be dangerous. If the air contains more than 3% CO₂, it can cause symptoms such as headaches, dizziness, increased heart rate, and difficulty breathing. At concentrations above 15%, CO₂ can quichly lead to unconsciousness and death. The boundary between healthy air and lethal gas can be extremely sharp; even a single step upslope may be adequate to escape death.

Since the Tajogaite eruption ended on December 13, 2021, high concentrations of CO₂ up to 20% have been observed inside the buildings of La Bombilla and Puerto Naos (La Palma, Canary Islands).  Anomalous concentrations of CO₂ are detected mainly in the ground-floor and basement of the buildings in Puerto Naos, and their distribution is not homogeneous or uniform throughout the Puerto Naos area (Hernández P.A. et al, 2022).  Because of the ultradilute nature of CO₂ in the atmosphere, chemical sorbents with strong CO₂-binding affinities are typically employed for CO₂ capture. For this study, we set up a network of 45 alkaline traps stations located on the ground-floor (streel level) inside buildings of Puerto Naos. These chemical sorbents were made up KOH 1.2 M and replace weekly. The aim of this study was to distinguish between indoor areas that had high levels of CO₂ in their alkaline traps and those with lower levels of CO₂. This was done through weekly surveys conducted from May to October 2022 in order to identify and define areas with the greatest CO₂ hazard. The statistical analysis of the results shows that 75% of the variance of the amounts of CO₂ retained weekly in the alkaline traps seems to be related to an endogenous CO₂ source while 25% of the variance observed is related to external variables.

 

Hernández, P. A., Padrón, E., Melián, G. V., Pérez, N. M., Padilla, G., Asensio-Ramos, M., Di Nardo, D., Barrancos, J., Pacheco, J. M., and Smit, M.: Gas hazard assessment at Puerto Naos and La Bombilla inhabited areas, Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.