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GAS DETECTION - TOXIC, OZONE -
INTRODUCTION |
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Introduction |
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Why measure it?
In the upper atmosphere "good"
ozone (O3) protects life on
Earth from the sun’s ultraviolet rays. At ground level "bad" ozone
is a criteria pollutant that is a significant health risk,
especially for people with asthma. It also damages crops, trees and
other vegetation and a main component of smog.
Where does it come from?
Ground level ozone is not emitted
directly; it is created by chemical reactions between oxides of
nitrogen (NOx) and volatile
organic compounds (VOC) in the presence of sunlight. Emissions from
industrial facilities and electric utilities, vehicle exhaust,
gasoline vapors, and chemical solvents are some of the major sources
of NOx
and VOC.
How do we measure it?
The O3
analyzer module continuously measures ozone in ambient air. Air is
actively sampled by a pump and travels through a glass and Teflon
coated inlet system to the analyzer module. The ozone analyzer
module incorporates a gas sensitive semiconductor sensor. This
sensor is a tungsten oxide (WO3)
formulation that is particularly sensitive to
O3 when
operated at elevated temperatures. By subjecting the sensor to
periodic zero flow conditions and temperature cycling, the analyzer
module compensates for drift and cancels interferences from NO2
and VOCs.
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