High levels of
the pollutant ozone are predicted to exceed the
federal standard today, Tuesday, March 12,
which is declared an “ozone action day” in the
Upper Green River Basin.
This forecast follows Sunday’s highest-yet
hourly levels, which the Wyoming Department
of Environmental Quality’s Air Quality Division
had predicted – and also an exceedance
of the 8-hour average that was not predicted.
The federal standard is 70 parts per billion
for an 8-hour average and above that is considered
unhealthy. High levels can affect the
young, old, heavy outdoors users and those
with respiratory ailments.
Sunday, the AQD’s Boulder station recorded
a 1-hour peak of almost 120 ppb. Eighthour
averages, which had in the previous week
risen to 85 ppb, reached an exceedingly high
mark Sunday of more than 90 ppb.
In fact, the day before, the AQD had predicted,
“No 8-hour elevated ozone values are
expected on Sunday, March 10, in the Upper
Green River Basin. … An Ozone Action Day
has not been issued for Sunday.”
Daily alerts have been leading up to Sunday’s
highs and Monday and Tuesday’s designations
as “ozone action days.”
On Friday, the AQD had predicted potentially
high hourly levels in its “ozone outlook”
alert for Sunday, March 10, through Tuesday.
Earlier, the AQD declared “ozone action days”
for March 5 and 6 and “ozone outlooks” for
March 7 and 8.
On an “ozone action day,” the energy industry
and public put into place contingency
plans to reduce ground-level emissions that
form the pollutant.
Since mid February, the Air Quality Division
has issued several ozone outlook alerts
for potentially high hourly levels of ozone to
exceed the federal standard.
The “winter ozone season” is observed
from January through March when winter conditions
include high amounts of snow cover,
bright sunlight, temperature inversions, volatile
organic compounds and nitrogen oxides.
Current information on ozone levels at
AQD monitoring stations at Boulder, Pinedale,
Daniel South, Big Piney and Juel Spring is at
www.wyvisnet.com. To see previous 1-hour
and 8-hour levels at any site, plot recent data
for the appropriate time period.
More information on ozone and its health
effects are at http://deq.wyoming.gov/aqd/ and