Then, they can affect various body organs,
especially the heart and lungs, and may cause serious health effects. Based
on particle size, particle pollution is grouped into: a) “inhalable coarse
particles” which have a diameter of 2.5 µm to 10 µm, and are found near
roadways and industries, and b) “fine particles” < 2.5 µm in diameter such
as those found in smoke and haze; they can form when gases emitted
from power plants, industries and automobiles react in the air. Ozone (O3)
is a gas composed of three oxygen atoms. In the presence of sunlight, it
is created at ground level by a chemical reaction between oxides of
nitrogen and volatile organic compounds. Ozone might have harmful
effects when formed in the earth’s lower atmosphere, i.e. at ground level.