 1.
What is Ozone (O3)?
Ozone
(O3)
is a gas that can form and react under the action of light and that
is present in two layers of the atmosphere:
the stratosphere
and the troposphere.
In the stratosphere,
ozone forms a layer that shields the Earth from ultraviolet rays.
However, in the lower atmosphere
(troposphere),
ozone (O3)
is the most important photochemical
oxidant. There, it is a secondary pollutant formed when precursor
pollutants such as nitrogen
oxides (NOx)
and volatile
organic compounds react under the action of light.
Near strong emission sources of nitrogen
oxides (NOx),
where there is an abundance of NO,
ozone
is “scavenged” as it reacts with NO. As a result its
concentrations are often low in busy urban centres and higher in
suburban and adjacent rural areas. However, ozone is also transported
long distances in the atmosphere
and is therefore considered a trans-boundary problem.
Because the formation of ozone
requires light, ozone concentrations fluctuate depending on season
and time of day, with higher concentrations in the summer and in
the afternoons.
Controlled exposure studies on humans
and animals have provided evidence that ozone
can cause adverse health effects. However, more research is needed,
especially addressing the spatial and seasonal patterns of ozone
exposure and related health effects. More...
Source: Queensland Government EPA,www.epa.qld.gov.au
|
