1. Fundamental concepts

1.1 Historical background

Anthropogenic air pollution appeared with the mastery of fire by human beings, 350,000 or 450,000 years ago. Combustion, inseparable from human evolution, contributes to emissions of both gaseous (CO, NOx, CO ₂ ...) and particulate compounds. Closer to home, writings already testified to such phenomena. For example, Seneca, a Roman senator and philosopher, wrote 2,000 years ago: "As soon as I have left behind me the oppressive air of the city and the stench of smoking chimneys which, once their fires are lit, vomit up all the pestilent fumes and soot they contain, I shall feel quite another man". So spoke this philosopher of Rome, a city with a population of around one million.