In fact, the concentration of ozone is measured in Dobson units. So, even the units are named after him. The normal thickness of the ozone layer is 3-5 mm which is 300-500 Dobson units. After 8 years of making Dobson’s machine, Sidney Chapman made equations of ozone formation and introduced the Chapman cycle to the world. The ozone present at the ground level, as we told you, is harmful to humans. So it is called Bad Ozone.
When Scientist Schonbein was working with ozone, he suffered chest pains and difficulty breathing. He also observed that in an ozonized environment, the smaller animals would die. Today, bad ozone is increasing due to the use of fossil fuels.
Specifically, the nitrogen oxides, NOXs, like nitrogen dioxide, when they are released due to burning coal or from the exhaust of a car, ozone is formed at the surface level. Due to the heat and UV rays the nitrogen dioxide is split into nitrogen oxide and a single oxygen atom. And this oxygen atom reacts with the oxygen molecule to form ozone.
Besides nitrogen oxides, VOCs are also responsible. Like benzene, which is produced from gasoline combustion. Sometimes it evaporates from paints that are applied on the walls. Or it is found in nail polish removers. It is worth noting that the level of bad ozone forming often depends on the weather conditions. In the summer months, more of it is formed. Due to more UV radiation and more heat. On the other hand, when it rains and there is high humidity, fewer ozone molecules are formed. This is why ozone is also considered an air pollutant.
