What does CO₂ have to do with Covid?

Last modified October 13, 2021

Learn what CO2 has to do with Covid and how measuring the concentration of CO2 in the environment can help reduce the possibility of contagion.

By now who else, who less, knows what there is a relationship between CO2 and Covid from the multitude of times it has been commented on in the media, but many people do not know exactly what that relationship is.

This article was part of the introduction of the tutorial for the construction of the homemade CO2 meter but the article was already beginning to have a huge length, so I have decided to separate this part and keep it in its own space Independent.

❓ What does CO₂ (Carbon Dioxide) have to do with Covid-19?

Absolutely nothing. However, these two words together are on the lips of many experts in the health and scientific community. Why? Keep reading…

CO₂ is a dangerous gas for humans. In high concentrations it can cause ailments such as vertigo, headaches, increased blood pressure, accelerated heart rate, and in the most severe cases it can lead to suffocation and loss of consciousness.

We have been talking and hearing about the Coronavirus for months at all times, maybe too much for our good mental health, so I'm not going to comment on anything about him. Everything I can say about the Coronavirus, surely, you already know.

You just have to remember that, today, the best way to prevent Covid is to protect yourself against the SARS-CoV-2 coronavirus and this is achieved through fairly basic, almost hygienic practices. And at the bottom of all this is that who avoids the occasion avoids the danger.

⚠️ The air we breathe and the Covid

Even though CO₂ has no direct relationship with Covid, If that there is a very important indirect relationship and, this is, the quality of the air we breathe and the viral load that air may have.

When there are several people in a room and one of them is a carrier of the virus, this remains suspended in the air for a variable time, at the expense of other people sharing the room being able to breathe it and catch. These are the famous aerosol sprays, of which we have heard so much lately.

The more time passes, the more the viral load present in the air increases, with which more it goes increasing the danger from other people catching it.

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For this reason, adequate air renewal in the room is essential, and this is achieved by ventilating.

In work environments it is more or less common to have a forced air system that facilitates ventilation and air exchange (and even filtering by HEPA filters) but this it is very rare in private homes, where the only option is usually to ventilate by opening the windows.

The problem is that the virus is invisible, we cannot look at the air and see the viral load it has to decide to ventilate when we see that it is necessary. This is where the CO₂ meter comes into play.

As the Superior Council of Scientific Investigations (CSIC), in its guide to reduce the risk of contagion, CO₂ measurements are one of the best ways to control that we are maintaining adequate ventilation:

CO₂ (carbon dioxide) it is a gas that we expel naturally when we breathe, so that knowing the concentration of this gas in the environment we can have an idea of what «loaded»What is the air in that room, what allows us to decide when to ventilate and for when to do it.

In other words, knowing the CO2 concentration allows us to know the "Second-hand air" that we are breathing.

This is especially important in winter, since, due to the low temperatures, we tend to ventilate much less, delaying the time to open the windows.

Illustration CO2 @GloriaMomay
Illustration CO2 @GloriaMomay

How he says on Twitter Spanish professor and scientist, from the University of Colorado, José Luis Jiménez, one of the world's leading authorities on the transmission of COVID-19 through aerosols, echoing the words of Dr. Holte:

💹 The CO₂ figures in the air

CO₂ is naturally present in the air in an approximate proportion of 415 ppm (415 parts per million, or what is the same 415 parts of CO2 per million parts of air).

The trick is in control how many parts per million CO₂ we have at all times and maintain adequate ventilation so that this number does not reach a certain figure, which we consider too high.

In the following table, created by CoviBlock, you can see what part of the air you breathe already has been previously breathed in by another person, measuring the level of CO2.

And what is that magic number, or from how many parts per million of CO₂ do we have to vent?

There is no magic number, but we can use some standards to help us understand when the number is too high. The maximum CO₂ concentration recommended by the WHO for healthy environments is 1000 ppm. As a general rule, a concentration of CO₂ less than 800 ppm is considered adequate, although the ideal is that it should be closer to 500 ppm.

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I leave you the following infographic by Sergio Coscolin (@SergioCoscolin), which explains it very well and I take the opportunity to thank you for your magnificent informative contributions, in the form of infographics.

RITE regulations in educational centers

To have an idea of what the standards on air quality indicate, we can take as an example the regulations for educational centers.

In Spain the main regulatory framework on indoor air quality is the Regulation of Thermal Installations in Buildings (RITE), which classifies air quality into 4 categories: IDA 1, IDA 2, IDA 3 and IDA 4 (for its acronym of English “indoor air”).

  • EDUCATIONAL CLASSROOMS, IDA category 2 (good quality air) is required, to which the RITE assigns a limit value of +500 ppm on the CO₂ concentration outside. 
  • NURSERIES the requirement is increased to IDA 1 (optimum quality air) to which the RITE assigns a limit value of +350 ppm on the CO₂ concentration outside. 

In these COVID times, most of the experts worldwide It seems that they recommend that the CO₂ concentration figures in educational classrooms, and in places such as offices, shops, hairdressers, etc., be maintained below about 700 ppm, to ensure sufficient aeration.

Examples and actual figures of CO₂ concentrations in a home

To better understand where these CO₂ values move, I am going to put you as an example my own house.

This graph corresponds to the concentration of CO₂ in the living room of my house on a Saturday in November (everything closed tight because of the cold), completely ignoring data from CO₂ (as I think they would in any normal house).

CO2 Salon data chart

What can we see in this graph?

Basically that CO₂ levels are very high, and that they are maintained above WHO recommended values most of the day.

  • Despite the fact that, when the room is ventilated, around 2:00 p.m. and for half an hour, the CO₂ values fall close to 450 ppm, the zero air renewal causes the values to rise again quickly, reaching worrying values 2300 ppm.
  • This day, the five members of the family (and the dog) have seen a movie on the projector in the living room, which explains this notable increase in CO₂ in the afternoon.
  • It is clearly appreciated how the CO₂ has risen rapidly from 3:00 p.m. (when we have all gathered to eat).

As you see, the air quality in this room leaves a lot to be desired.

The data in the living room is taken with a Netatmo weather station, which has an indoor CO₂ sensor.

The situation can be much worse. Look at the following graph with the data recorded on a normal night in October, in a normal bedroom occupied by two people and a dog medium:

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CO2 concentration reaches 3921 ppm!

In the following graph you can see the CO2 data from my cave (my room of tinker):

This data is updated in real time, if you stay a while looking at it, you will see how each minute, approximately, a new measure appears.

In the tutorial to build the homemade CO2 meter I show you how you can create a graph like this, easy and Complétamente free.

What do I have to do to maintain good air quality?

The most important thing is ventilation, that small action that we have not paid much attention to for many years and that, fortunately, is becoming more and more a matter of conversation in bars, raising awareness of all kinds of people.

Instead of leaving you here an endless parade, I'm going to leave you the following infographic by Sergio Coscolin (@SergioCoscolin), which explains it very well.

🛒 What if I want to buy a ready-made CO2 meter?

If, for whatever reason, you don't want to build your own homemade CO2 meter, you have the option of buying a commercial one. Plug and play.

There are many models on the market, but, I must warn you that many of them are worth absolutely nothing, in order to measure the concentration of CO2, because they have a type of sensor that is affected by all types of gases and the meter is not capable of distinguishing CO2 from any other gas (and there are many gases in the air that go and they come, so you'll never know if it's measuring CO2 or something else).

Whichever meter you buy, I recommend that you buy one that has an NDIR sensor (And keep in mind that, if it doesn't wear it, it probably won't wear it).

If you want a commercial meter that is not very expensive and that works well, I would propose one of these two options:

No products were found.

Netatmo NHC-EC - Quality control of your home environment, indoor air, temperature, humidity, sound and CO2, Rose Gold, 4.5 x 4.5 x 15.5 cm
  • Air quality level, humidity and temperature, noise
  • Tips on how to create a healthy environment
  • 3 profiles in the application; baby, person with asthma, general
  • Real-time notifications, ios 9 or higher for iphone, ipad, ipod, android 2 or higher
  • Connect multiple home coaches to your smartphone; to control multiple rooms

I have this one down here that is very similar, but with some additional things that make it a weather station:

Netatmo NWS01-EC Wireless Indoor Outdoor Weather Station With Wifi, Compatible with Amazon Alexa and Apple HomeKit
  • Control your indoor and outdoor environment in real time: indoor and outdoor temperature, humidity and air quality, indoor noise level, barometric pressure
  • Receive alerts in real time: with our weather station, configure indoor and outdoor alerts and receive notifications on your smartphone; you will know when to ventilate with the ventilation alert
  • Access your data remotely and with your voice: access your weather measurements with ease and at any time from your smartphone, tablet or computer, or by using your voice to interact with alexa on amazon echo or with siri thanks to the compatibility with apple homekit
  • Analyze the past: access the history of your data to observe what happens when you are not there or analyze the graphs to understand the weather trends
  • Foresee the future: check the 7-day weather forecast to adapt your clothing and your outdoor activities

If you want to see more models available at a good price, the best sellers, the best offers, etc. you have the option to visit this CO2 meter buying guide.

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