Being a trace gas, ozone is a natural component of the atmosphere. In the ground-level air layer, it is formed under sun radiation from the so-called ozone precursors.
Pollution by particulate matter (PM10 and PM2.5) is the environmental factor with the greatest negative impact on human health. The effects range from respiratory ailments to lung cancer. The main pollutants are industry, small-scale furnaces, traffic and agriculture.
