What is ozone and why is it dangerous?

Ozone, chemical formula O₃ (3 atoms of oxygen) is a gas that is always present in our atmosphere. It is formed when oxygen, O₂it is first broken down by ultraviolet rays into two separate oxygen atoms, and then the three atoms form O₃molecule or ozone molecule. So all you need is oxygen and strong ultraviolet rays from the sun.

Ozone usually forms only at high altitudes, in the stratosphere, where it protects us from harmful ultraviolet rays. If this protective shield is not present, our skin will quickly become damaged, resulting in DNA damage (and thus cancers).

A few decades ago, it was proven that high ozone concentrations in the air are decreasing. Then it was referred to as a “hole in the ozone layer”. The reason is attributed to air pollution from CFCs or “chlorofluorocarbons” that were mainly present in refrigeration systems. Fortunately, this problem has been addressed on a global scale and since 1989 the Montreal Protocol, an international treaty to protect the ozone layer, has entered into force. Since then, the ozone layer has begun to recover, with the lowest ozone concentrations over Australia and New Zealand.

Therefore high-altitude ozone is indispensable, which is why we call it “good” ozone. There is also “bad” ozone. On very sunny days, with strong UV rays, ozone can also form at lower altitudes from a reaction to air pollution. This can cause health problems for humans. When you inhale ozone, your lungs can become irritated and you may develop breathing problems. Therefore, it is not recommended to exercise hard on hot, sunny days. It is not in vain.

Concentrations of “bad” ozone in the troposphere are constantly measured and monitored by the Flemish Environment Agency and the Interregional Environmental Cell. When certain threshold values ​​are exceeded, residents are notified or alerted.