Coronavirus: measuring carbon dioxide can help save lives – telam

Andrea Pineda Rojas: Carbon dioxide (CO2) is a gas emitted during exhalation during breathing. Outdoors, its concentration is close to 400 ppm (parts per million) and is approximately constant, which serves as a benchmark

Measuring carbon dioxide (CO2) as an indicator of air ventilation in a closed environment is one of the most recommended measures to prevent the spread of the coronavirus by inhaling accumulated aerosols (small drops that we emit when we exhale ), which today is one of the main routes of transmission, warned specialists.

“Carbon dioxide (CO2) is a gas emitted when exhaling during breathing. Abroad, its concentration is close to 400 ppm (parts per million) and is roughly constant, which serves as a benchmark, ”Andrea Pineda Rojas, researcher at the Center for Research on the Sea and the Sea, told Telam. atmosphere (CIMA). du Conicet.

And he continued, “When everything is closed, CO2 accumulates and increases its concentration, with which CO2 levels well above 400 ppm give a measure of the build-up of aerosols in an environment, and suggest that it is necessary to ventilate, which means renewing the air ”.

Pineda Rojas said that “when an infected person speaks or breathes, they constantly emit aerosols containing potentially infectious viruses; the highest concentration of these aerosols is right in front of the person and decreases as the distance increases, which is why this is so important. maintain a physical distance. In closed places without ventilation, aerosols accumulate and can cause contagion at distances greater than two meters from the infected person “.

The specialist underlined that “the importance of ventilation has to do with the reduction of the risk of contagion by inhalation of these aerosols which accumulate in the environment when the air renewal is not adequate” .

“At first we knew that if the large drops emitted by a person with coronavirus who cough or sneeze reach another person’s eyes or mouth or fall on a surface and someone touches them with their hand and carries to his mouth or his eyes, it is contagious, described the professor and researcher Conicet Jorge Aliaga to Télam.

“But over time we have learned that in addition, when we speak, it emits very small drops, called aerosols, where the virus can also be found and that these micro-drops have two particularities: they are much more in quantity than large drops and they stay suspended in the air for hours, ”he added.

According to a survey conducted by Spanish scientist José Luis Jiménez, with his research group from the University of Colorado -United States-, “of all the scientific literature that exists, aerosol transmission is the one that collects the most evidence “.

As proof, the “cases of super diffusion” or “super contagion”: the most famous was the choir of the United States, Skagit, who met while respecting the distance for two and a half hours to sing; one person was infected and 52 of the 60 participants were infected, including those who were 13 meters behind the person with Covid-19.

Referring to the maximum concentration of CO2 to assess that an environment is ventilated, Aliaga stressed that “what is taken as a recommendation is that it does not exceed 800 ppm, it must be remembered that in the open air the concentration is about 400 ppm “.

And he added that “this measure would be essential in any interior space where converge people who do not live together (schools, offices, offices, waiting rooms, shops, etc.) and is done with equipment which, although ‘they have different prices in the market, are affordable for institutions or businesses and would reduce infections and save many lives. “

According to Aliaga, “commercial equipment, which should be placed on a table as if it were a clock, is available on the Internet from 18,000 pesos, while more complex equipment, intended for more technical, can reach up to 50 thousand pesos “.

The specialist, who has been working on this aspect of the pandemic for months in addition to analyzing the data, designed a home measuring device in which he spent less than 7 thousand pesos, and downloaded the instructions from the Internet “from so that if an individual or educational institutions want to acquire the parts and assemble them and know how to do it. “

“For example, technical schools could make them and the parts could be purchased through the state, which would certainly reduce the cost,” he said.

With this device, the researcher performed different tests: “Although it is necessary to validate the absolute measurement values ​​with commercial meters, some conclusions can be obtained depending on how the concentration has increased or decreased”, a he describes.

And he explained that “if it is placed near a window the indicator is similar to the open air, if it is far away it starts to increase; if everything is closed and we start talking it goes up to 800 or 900 in 15 minutes “.

“This means that in this room, where there could be three people two meters apart without a problem, with everything closed in a matter of minutes, any one of them could breathe the other’s exhales and if one was infected, it could be dangerous, ”he said.

Finally, Pineda Rojas warned that “Being outdoors or in an environment with good ventilation greatly reduces the risk of becoming infected by inhaling accumulated aerosols (contagion beyond two meters), but ventilation does not affect the risk of contagion nearby, so using a mask and keeping your distance is always essential ”.