A comparison to alcohol.
Many adults have experienced the effects of alcohol. But not so many have experienced the effects that CO2 has on the body, right? Wrong! Actually most of us have been in poorly ventilated meeting rooms. First you become less and less concentrated. Then we start feeling tiredness. Some of us might even doze off. In some rare cases, the room might be so badly ventilated, that we even start getting headaches. All of these effects are related to elevated levels of CO2.
In this article I will show what the effects of CO2 on your body are. From being harmless at low levels, to giving headaches, to giving increased calcification of your kidneys and all the way to being deadly at very high levels. Furthermore I compare this to the effects of alcohol, which most people understand.
Levels of alcohol in the blood (Blood alcohol content or BAC) is measured in tenth, hundredth or even thousandth of a percent. There is ample documentation of the effects on behavioral change of alcohol in the blood. Even though hangovers are not a pleasant thing, luckily the effect of alcohol is gone again within about 48 hours, once we stop drinking. The same is true for the effects of CO2 once the higher exposure level is removed.
There are however also long term effects in the cases where people are drinking daily. The higher the daily dosage is, the harder the toll on the body.
Alcohol dosage can be described in units of alcohol equivalents. One unit is for example one Beer of 0.33 cl with an alcohol percentage of 5%.
Depending on gender and weight, it is possible to approximately calculate how much your BAC will rise when drinking a certain amount of alcohol units.
One example set of formulas (Widmark) are as follows:
BAC = [Alcohol consumed in grams / (Body weight in grams * r)] * 100; r = 0.55 for females and r = 0.68 for males.
One US Standard Drink contains 14 grams of alcohol, which is equivalent to: 1.5 oz of Gin or Whiskey (40%), 12 oz of Beer (5%), 5 oz of Wine (12%). A really thorough explanation of how to calculate the BAC can be found here.
Actually CO2 levels are also measured in a similar way to alcohol levels. It is very normal to see the abbreviation ppm, which stands for parts per million.
To illustrate this, picture 1.000.000 balls, which represent the composition of our atmosphere. Approximately 780.800 of these balls would be Nitrogen. 209.400 would be Oxygen. About 9.300 would be Argon. Only about 400 would be CO2. The rest is other gases like Methane, Nitrogen dioxide and other gases, in very low quantities.
The current level of CO2 in our atmosphere as of April 2019, is 413 ppm, or translated into percentages, 0.0413%.
In many confined spaces such as classrooms, meeting rooms or even badly ventilated bedrooms, CO2 levels can rise to levels as high as 3.000 ppm or 0.3%.
As with alcohol, the time of exposure to increased levels of CO2 matters. The long term effects of CO2 exposure at higher levels is however not as well documented as those for alcohol. There is also very little data available of the effect of increased CO2 levels on the development of children.
Visualizing the effects of alcohol versus CO2
In the following illustrations, I have tried to visualize the short term and long term effects of both alcohol and of CO2 on the human body. I have categorized the effects into the 7 following different categories:
Beware that the levels and effects in these illustrations are somewhat individual and not absolute.
Before you dive into the illustrations, I would like to give a short clarification about what is meant when looking at the the long term effects (weeks, months and years). For alcohol one should think of a person consuming the mentioned dosages every day, during the mentioned period. As for the long term effect of CO2, one should think of being exposed to the levels of CO2, without a break during those long periods.
Lets start with a healthy lifestyle where we breathe fresh air and drink almost no alcohol:
The next illustration shows the effects of moderate alcohol consumption and CO2 levels as we find them indoors. I would think a situation that is normal in the western world. When looking at the long term effects (Months, Years), most people with a healthy lifestyle will not fall into these categories. We do take a break from drinking and we do go out into the fresh air.
When increasing both the alcohol consumption and the CO2 level further, the harmful effects increase. Especially when looking at the long term effects. While 2 glasses of beer or wine are not harmful when consumed occasionally, they will be more harmful if it turns into a habit. For the increased CO2 levels as seen in submarines or space stations, these are reported to cause headaches and other side effects.
As we further increase alcohol concentrations, the effects also increase. For the alcohol consumption at these levels over a longer time, one would be classified as an alcoholic. CO2 levels as high as described in the following illustration are rather rare and only few people risk exposure to such high levels.
A person drinking an amount of alcohol described in the following illustration would be called a heavy drinker, especially if this happens on a daily basis. When exposure to CO2 levels this high at work are unavoidable, the exposure time should be kept below 15 minutes.
As we further increase the levels, the effects become more and more dangerous, even after short exposure times.
Go high enough with the dosage of something that is harmful, and it will become deadly.
Putting it all together
In the last illustration I have put all of the above illustrations together in order to give an easier overview.
As I tried to show, the effects of alcohol and of CO2 are similar in some ways, but differ in others. Alcohol has a stronger effect on the body, which can be seen by the fact that the negative influence of alcohol already shows at lower dosages. CO2 is not a poisonous gas, increased levels in the air we breathe, do however have negative effects on our body.
Luckily we have a choice to avoid the negative effects of both alcohol and of CO2. It is therefore important to keep track of CO2 levels indoors and ventilate, when needed, in order to avoid the negative effects. When a person exhales, the CO2 concentration is about 4%. That means if you put enough people into one room, the CO2 concentration can rise rather quickly. To avoid negative effects, where people are doing normal work, about 2 to 3 cubic meters of air should be exchanged with fresh air, per hour per person.
One surprising fact is, that I was not able to find information about the effects of long term exposure to increased levels of CO2. This is an area for future research.