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E-M:/ Ozone Concentrations

Enviro-Mich message from Isaac Elnecave <isaacmec@voyager.net>

Yesterday, Michigan got a great example as to why the current air
are out of date and we need new ones.

Ozone (ground level smog)  is currently measured over a 1 hour period.
If ozone levels exceed 125 parts per billion at a monitor, the level of
ozone in that area has exceeded the standard. Yesterday, the monitor in
New Haven (Macomb county) recorded a maximum value of 124 parts per
billion.  According to the air standards, the area was not in violation.
However, does anyone think that the air was not unhealthy to breathe
because it didn't exceed the old 125 ppb mark.

That is why EPA proposed to measure ozone levels over an 8 hour period.
over 8 hours recognizes the fact that many people are exposed to high
ozone levels for
 a long time.  In addition, it is a more accurate measure.  This way the
state is not
measuring a brief period of time with high ozone levels but gets a
representative of air
quality throughout the whole day.  The 8 hour standard is exceeded after
ozone levels
exceed an 8 hour average of 85 parts per billion.  (Note studies have
shown that people
suffer adverse health effects from ozone at levels as low as 60 parts
per billion.)  In
yesterday's case, the air monitor in New Haven recorded an 8 hour
average of  102
parts per billion.  In one case, the standard says the air is healthy
(under the old
standard) and under the new standard the air quality is properly
classified as unhealthy.

Isaac Elnecave
Michigan Environmental Council

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