Ozone concentrations in 2005

These data are part of the effort to provide the most detailed data on air quality
in CAPLTER. This dataset represents spatially interpolated ozone (O3) levels as
measured by monitroring stations of the Maricopa County Air Quality Department. O3
is a naturally occurring compound in which three oxygen atoms combine together. This
is an unstable combination, and ozone is continually going through a natural cycle
of being formed and then converting back to the more stable “normal� double
oxygen compound (O2). The cycle occurs fairly rapidly. In the stratosphere (6 miles
and more above the earth), naturally occurring ozone has a beneficial effect of
screening out harmful ultraviolet light from the sun. However, ground-level ozone is
a pollutant and is a major component of the brown haze that is often observed in the
Maricopa County valley. Ozone is not directly emitted into the air, but rather forms
in a complex reaction that involves heat, sunlight, and a “soup� of toxic
pollutants, especially volatile organic compounds (VOCs). Some of the most common
sources of VOCs are gasoline vapors, chemical solvents, and combustion products of
fuels and consumer products. Ozone is created by sunlight acting on nitrates (NOX)
and VOCs from motor vehicles and stationary sources, and can be carried hundreds of
miles from their origins. Ozone affects the respiratory system in people and
animals, and also affects the growth of plants.