More about Ozone

Unlike other pollutants, ozone is not directly emitted to the atmosphere. It is a secondary pollutant formed by a complex reaction with other "primary" pollutants.

Ozone is formed by a reaction involving oxides of nitrogen (NOx) (AENV NO2 Indicator) and volatile organic compounds (VOCs) in warm, sunny conditions. Motor vehicles are significant sources of both of these "primary" pollutants. In rural areas, natural emissions from trees and vegetation are a major source of volatile organic compounds. Ozone is also transported to the ground from the upper atmosphere by natural weather processes.