Properties
- ground-level ozone: secondary air pollutant produced in the troposphere from nitrogen oxide and volatile organic compounds when exposed to sunlight
- fairly pungent smelling, colourless gas
- low solubility in water
- one of the strongest oxidants and irritant gases
- highly corrosive to human, animal and plant tissue as well as materials
Main sources
- motorised road transport (precursor pollutants nitrogen oxides)
- industrial and commercial processes and installations (precursor pollutants volatile organic compounds)
Impacts
- irritates the respiratory mucosa, causes tightness in the chest, reduces lung function
- is harmful to plants
- contributes to the greenhouse gas effect (in the lower air layers)
Ozone ambient limit values
100 µg/m3 98% of the 1/2-h-means of a month of less than or equal to 100 µg/m3
120 µg/m3 1-h-mean; may be exceeded once per year at most
Status and changes
From 1990 to 2014, nitrogen oxide emissions fell by around 50% and volatile organic compound emissions decreased by 70%. Despite rising mean ozone levels, this prevented an increase in the maximum values. In the summer months, the ambient limit values are frequently exceeded on a large scale.
