Is There Too Much Carbon Dioxide in Your Classroom?

You have been stuck in your classroom for the whole afternoon, and there is another half hour until it is time to go home. You have a pounding headache. You cannot focus or think properly. What’s going on?

It just might have something to do with the air you are breathing. Let’s look at what happens to your mind and body when the air you breathe has more carbon dioxide (CO₂) than it should.

What happens when you breathe?

Your body uses oxygen to create the energy you need to live. When you breathe air into your lungs, the oxygen in it sticks to your red blood cells. This way, it reaches your organs and muscles.

Through a complex process called cellular respiration, oxygen goes through a series of chemical reactions in order to form energy, CO₂, and water vapour. Using that energy, your heart can pump, your brain can think, and your muscles can contract. Meanwhile, the CO₂ and water vapour are released back into the environment.

So, what’s the problem?

CO₂ is a natural part of the atmosphere. You may have heard that too much CO₂ can affect the environment. However, scientists have found too much CO₂ can also affect people indoors.

When a room has lots of people and poor ventilation, the concentration of CO₂ may get too high.

• Air is made up of a combination of different gases (not just oxygen!)
• Nitrogen 
• Oxygen
• Argon
• Xenon
• Hydrogen
• Helium
• Krypton
• Carbon dioxide

High levels of CO₂ in the air can reduce the amount of oxygen you breathe in. That means there is less oxygen going to your brain. If your classroom has too much CO₂, you might find it hard to pay attention to your teacher, concentrate on tests, or even stay awake. In one study, scientists found that high levels of CO₂ can even make it harder for you to make decisions.

Too much CO₂ can also make you feel physically bad. You might start to get a headache, feel dizzy or nauseous, get tired, or have trouble breathing. Poor indoor air quality may also worsen allergies, asthma symptoms and lung health.

Did you know?

The average Canadian spends about 90% of their time indoors.

How much CO₂ is too much? 

To put a number to it, the average outdoor atmospheric level of CO₂ is around 400 ppm (ppm = parts per million). Different people start to feel the effects at different CO₂ levels. Some people start to feel tiredness and other effects at CO₂ levels around 1 000 ppm.

What does ppm mean? Parts per million is a unit of concentration. One ppm means that you have one of something in a million of something else. The “something” and “something else” can be measured in molecules, masses, volumes, or whatever else you can think of. Normally, when we are talking about things in the air, we are talking about volumes. That’s why you’ll sometimes see ppmv or parts per million by volume.

Did you know?

One part per hundred (1/100) is more commonly referred to as one percent (%). This comes from the latin word “centum,” which means “hundred.”

Let’s get back to the issue of CO₂ in your classroom. Imagine your classroom holds a volume of 1 000 L of air and has a CO₂ level of 1 000 ppm.

1 000 L * 1 000 parts/1 000 000 = 1 L (* is another way of representing multiplication)

In other words, there is 1 L of CO₂ in the 1 000 L of air in your classroom.

CO₂ levels of 1 000 to 2 000 ppm can cause drowsiness. Headaches and other physical effects described above can begin at between 2 000 and 5 000 ppm. More serious, and potentially toxic, effects can happen when CO₂ levels are above 5 000 ppm.

How much CO₂ is in your classroom?

It is important to maintain low CO₂ levels inside. CO₂ can be measured using a simple electronic CO₂ meter that people can buy in a store or online.

So, when you are sitting in your classroom, how much CO₂ are you actually being exposed to? Between 2010 and 2015, 106 Toronto schools had air quality testing done. 43% of those schools had one or more classrooms with a CO₂ concentration above 1 000 ppm. This means schools need to do a better job at ventilating some of their classrooms!

Remember, 1 000 ppm is not high enough to hurt you. But it is high enough to cause some physical effects that can affect your grades.

So if you don’t feel well in a classroom, and think the air might have something to do with it, what can you do? You may ask to open a window, leave the door open, or take a break and breathe in the fresh air outside.

CO₂ levels affect everyone differently, so not all of your classmates will feel the same way you do. But if CO₂ levels are high, chances are, someone else is feeling bad as well. This means that it may be worth mentioning to a teacher or staff member who can find out what is wrong and fix it. Of course, this can happen anywhere, not just in the classroom. So whenever you’re inside, it’s a good idea to take a break every once in a while from your homework (or video games), open a window or go outside.