Introduction
The combustion of oil and its derivatives releases unburned hydrocarbons and nitrogen oxides into the atmosphere. In the presence of solar radiation, these two categories of compounds react with each other forming ozone, considered dangerous to health when present in the atmosphere, in direct contact with humans. This phenomenon, also known as photochemical smog (or simply fotosmog) is characteristic of peak hours in major metropolitan cities during the summer period.
The calculation model
The gas used as a reference for standardization is ethylene. The emissions of all other substances potentially capable of favoring this effect are expressed in kg of ethylene equivalent (category indicator), that is, related to the quantity of ethylene that can produce the same amount of ozone. The conversion factors used are indicated by the acronym POCP (Photochemical Ozone Creation Potentials), which allow the estimation of POCP through the quantity of ozone produced.
