Fernando bought a carbon dioxide meter less than a month ago. He was encouraged to do so because he will soon return to work in person in Mexico City and wants to check that his office is well ventilated.
This young 34-year-old journalist now feels more secure with his new gadget, similar in size to a cell phone, because he can objectively know the air quality of the space where he is.
“My meter has several levels: acceptable is when it marks between 400 and 700 particles per million, but when it exceeds 1,100 particles per million of carbon dioxide an alarm sounds to warn that the air is already very stale,” he says in an interview for Tec Review.
He has tested it in his small apartment, where he has marked the highest concentration of carbon dioxide when there have been four people living together inside.
“It was within the acceptable range and the alarm did not go off. I have also taken him to crossfit, but since I usually train near the entrance door of the gym, he has set the minimum for me ”.
The gadget cost 1,900 pesos to Fernando. On the internet, prices range between 700 and 6,000 pesos, depending on the level of functions and compatibility with digital ecosystems.
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Carbon dioxide meter
Carbon dioxide is a molecule made up of one carbon and two oxygens.
It is the air that we exhale, not only human beings, but any aerobic organism; that is, it needs to breathe oxygen to survive.
So high concentration of this gas in a crowded place is indicative that the exhaled air is stagnant, which lends itself to contagion of respiratory diseases such as Covid-19.
In accordance with Paola Castillo Juarez, professor-researcher at the Virology Laboratory of the National School of Biological Sciences (ENCB) of the National Polytechnic Institute (IPN), the carbon dioxide meter is a good ally to avoid infections.
“Indirectly it measures how much carbon dioxide is circulating in the room where we are. If the amount of this gas rises, then it is related to the ideal conditions for the spread of covid-19 ”, he expresses in an interview.
Just in a place without sufficient ventilation, neither the air nor the droplets (neologism derived from droplet and particle) of suspended saliva flow, and then people are more likely to catch it.
“In a place with stagnant air, it also lends itself to the spread of other diseases, not just Covid-19. People can get sick from any virus or any pathogen that is transmitted via aerosols, such as influenza for example ”, Castillo Juárez points out.
To recap, a large concentration of carbon dioxide indirectly expresses a lack of dispersion of respiratory debris, including droplets of saliva carrying the Covid-19 virus.
“If there is a sick person, the amount of virus that is expelled and that is not circulating will increase, so the environment becomes ideal for the spread of coronavirus,” says Castillo.
Viruses are not spiky green balls
This accurate description of the way in which Covid-19 spreads throws the oversimplified version of green marbles with spikes that float and cause contagions to the ground. The truth is that it has never been like this.
SARS-CoV-2 viruses do not travel alone, but in droplets of saliva, and they are not one, not 10, not 100, but many more.
“There is talk of millions of viruses per milliliter of droplet,” says this academic from the IPN.
This has been verified in an interview for Tec Review by Ana Lorena Gutiérrez Escolano, a research professor at the Center for Research and Advanced Studies (Cinvestav), who in her laboratory has seen up close how these tiny beings really are.
“Viruses are strict intracellular parasites; that is, they require a cell to multiply, but we should not imagine a virus as a ball with little beaks that is flying by itself, because normally it is going to be associated with a liquid ”.
This liquid is the small droplets of fluids such as mucus or saliva, where Gutierrez Escolano detects huge amounts of virus through a microscope.
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More than viruses, viral load
Based on these concepts, this expert defines viral load as the concentration of virus in a certain volume of body fluid of an infected person.
“The virus measures nanometers (a one preceded by eight zeros) and a cell is already on the micron scale (a one preceded by five zeros), so the difference is gigantic (equivalent to that between a million and a thousand)”.
Another factor to take into account is that the viral load varies according to the stage of the disease. It starts small, then reaches a peak and finally descends, because the body limits it in 80% of the cases, according to Gutiérrez.
“For example, when you are on the fifth or sixth day of infection, the expelled droplets will probably have much more virus, and in the following days the amount of virus will be much less.
On the other hand, if a person has just been infected with Covid-19, they can go home and will not infect anyone because they do not produce as many viruses in the first two or three days, when the viral load is lower, according to Gutiérrez.
“This happens with all infections, there are peaks of activity in which you will have a higher viral load or a higher bacterial load, and then it goes down.”
This Cinvestav researcher confirms that, indeed, in closed places, with little ventilation, the possibility of contagion increases, which is much more observed in times of low temperatures.
“And that is not just for SARS-CoV-2, but it is like that for all respiratory viruses. In winter the possibility of contagion increases, because normally people do not ventilate their rooms because it is cold”.
So far the scientific background of a virus linked to the measurement of the concentration of parts per million of that colorless and odorless gas whose chemical name is carbon dioxide.
Meanwhile, Fernando continues to carry his meter in his pocket, with which he also measures temperature and humidity in the environment; excitedly, he soon plans to use it on wheels.
“In the next few weeks I plan to travel by bus and I think it will be very useful there.”