On Clean Air
For these two reasons, measuring carbon dioxide levels in indoor spaces is a vital part of ensuring you, your family and your colleagues are breathing clean air.
Your lungs would have the surface area of a tennis court if they were spread out on the ground. They have evolved over hundreds of millions of years - since that first lungfish flopped onto a mud flat and took a gulp of air - to their present state of perfection. Your lungs enable you to take in the oxygen you need to make energy for your body and expel the waste product of that energy-making process, carbon dioxide.
Each time you take a breath, this pink, sensitive, microscopically thin, moist membrane comes into contact with a new batch of air molecules, and also whatever happens to be floating in the air at the time.
​
This means the lungs are a direct connection from the outside world to the inside of your body, just like the gut. And, just like the gut, the lungs evolved at a time when there were no infectious diseases, no artificial pollution and, critically, no “indoors”.
As long as the air contains a healthy mix of gases, and does not contain any contaminants, such as infectious particles, smoke particles, gaseous pollutants or allergens, then the whole process works fine.
As we know, however, the air we breathe in the modern world mostly isn’t as pure as the air was on the prehistoric Earth.
Carbon dioxide (CO2)
​
Let’s talk about carbon dioxide, which is unfortunately accumulating in the atmosphere as a result of burning fossil fuels and causing all the climate problems we are well aware of.
The importance of carbon dioxide as we talk about breathing healthy indoor air today is two-fold:
-
The direct effect of raised levels of carbon dioxide on the human brain and its capacity to perform complex tasks. This is very significant, with evidence of impairment at levels as low as 800ppm (the outside air is about 420ppm). School classrooms in Australia are regularly at levels of 2000 to 3000ppm and school buses can reach 9000ppm, which not only makes the kids sleepy, irritable and unable to concentrate, but puts them in danger by doing the same to the driver!
-
Raised levels of carbon dioxide are a very useful sign of a poorly ventilated space. If the air in an enclosed space is not being refreshed with outside air, then the carbon dioxide being breathed out by people accumulates, along with the viruses and other infectious particles they are breathing out. This increases infection risk, with the risk increasing rapidly the higher the carbon dioxide level.
For these two reasons, measuring carbon dioxide levels in indoor spaces is a vital part of ensuring you, your family and your colleagues are breathing healthy air.
Airborne particle
There are all kinds of particles floating in the air today, which were not floating in the air on the prehistoric Earth.
Infectious Particles
We now know that all kinds of infections float in the air, infecting people directly through the air and that for many infections, such as COVID, flu, RSV, this is a much more important method of transmission than through contact.
Knowing the carbon dioxide level in a room tells you how much of someone else’s just breathed out air you are breathing in again with each breath of your own, and so how much risk there is of catching an infection.
Smoke Particles
Here in Australia, bushfire smoke is a real and frequent danger to health. The small bushfire smoke particles (called PM2.5 particles) get right down into the furthest reaches of the lungs, where they can trigger existing lung diseases, such as asthma and can also cause cancer. Again, wearing an N95 respirator mask and/or switching on a HEPA filter are an effective countermeasure.
Allergens
Airborne allergen particles are a major cause of hay fever and asthma. Filtering them out with an N95 or a HEPA filter can do wonders for your health.