Low Level Ozone (O3)
Ozone is an unstable gas with a characteristic fresh,
penetrating odour. The smell is noticeable after thunderstorms,
where the energy from the flashes of lightning has created
short-lived ozone from the oxygen in the atmosphere.
While naturally occurring, ozone in the upper atmosphere, 'the
ozone layer', protects the Earth, ground level ozone (O3) is
harmful to health.
Ozone is not emitted directly from any man made source in
significant quantities, but is formed by a complex set of reactions
involving nitrogen oxides and hydrocarbons in the presence of light
from the sun.
Once formed, ozone can remain in the atmosphere for many days and
is often transported over long distances. It is for this reason
that a real reduction in ozone levels can only be achieved through
global action by everyone. Ozone is therefore not a pollutant
currently in the Air Quality Regulations. It is however still
considered when looking at air quality.
Nitric oxides destroy ozone; therefore ozone concentrations are
actually lower next to busy roads. For the same reason, ozone
levels are usually higher in rural locations than in urban
areas.
It is also a strong oxidising agent. Ozone is therefore a pollutant
that can damage your health, farm crops, vegetation and materials
such as rubber.
Back to What is air pollution?