CARBON DIOXIDE (CO2)
Carbon dioxide (CO2) is a colourless, odourless, non-flammable gas that occurs naturally in the Earth’s atmosphere in trace amounts. It is the fourth most abundant gas in the earth’s atmosphere after nitrogen, oxygen, and argon and exists at an concentration in the region of 400 parts per million (ppm) or 0.04%. A normal levels CO2 is not harmful and it has previously been thought that CO2 levels would need to reach a very high concentration at least 5000 ppm before they could affect human health, however a growing body of research is now suggesting that CO2 levels as low as 1000 ppm could cause health problems. A recent study published in the journal NATURE SUSTAINABILITY in 2019 reviews a total of 18 studies into human exposure to CO2. A number of these studies documented that CO2 levels can regularly exceed 1,000 ppm in overcrowded and poorly ventilated rooms such as classrooms, offices and bedrooms and observed that exposure to CO2 at these levels reduced cognitive performance and productivity. Chronic exposure to levels over 2000ppm has been linked to headaches, insomnia, nausea and more serious healthy problems including kidney calcification and bone demineralisation.