Yosemite National Park
Prepared: 9/12/16 Prepared by: Jim McNitt, Air Resource Specialist
Overview: The 62 acre YV-22 Ahwahnee Meadow prescribed fire project, is
located in Yosemite Valley on the north side of the Merced River, south of
Ahwahnee Road, east of Yosemite Village, immediately west of The Majestic
Yosemite Hotel, straddling Yosemite Loop Drive. The goal of this project is to
safely reduce hazardous fuel loading in Yosemite Valley, while achieving both
ecosystem management and restoration objectives. Smoke Synopsis: Smoke from wildfires continues to affect the park
and campfire smoke has been elevating the level of observed particulate matter
in Yosemite Valley at night. An approaching upper-level trough will improve dispersion
conditions from fair to good during the day on Monday and will increase wind
speeds starting Monday afternoon. Due to a nighttime temperature inversion smoke
produced by the fire Monday morning will not mix well vertically until late
morning when the inversion breaks down and the surface wind speed increases. During the afternoon the smoke will be transported to the northeast. Outlook: Expect smoke dispersion
conditions tomorrow to be fair in the morning and good in the afternoon on
Tuesday and fair on Wednesday. High pressure is expected to build back in and
dispersion conditions will begin to deteriorate by Thursday.
Location
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Yesterday
9/11/16
Observed*
|
Day 1
9/12/16 Forecasted |
Day 2
9/13/16
Forecasted
|
Details for avoiding smoke during the worst hours of the day. The
Day 2 forecast assumes that all ignitions are completed on Day 1.
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Yosemite Village and the Yosemite Valley Elementary School
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Good
|
Moderate
|
Moderate
|
People with heart or lung disease, children
and older adults should reduce prolonged or heavy outdoor exertion during the
morning.
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The
Majestic Yosemite Valley Hotel
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No air
mintor located at this site
|
Unhealthy for Sensitive Groups
|
Moderate
|
People with heart or lung disease, children
and older adults should stay in air conditioned vehicles or buildings if they are near
Ahwahnee Meadow during ignition on Day 1 and reduce
prolonged or heavy outdoor exertion during the morning on Day 2. The 1-hr
values of PM2.5 will be highest during the day on Day 1 during ignition.
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El Portal
|
Good
|
Good
|
Moderate
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Disclaimer: These predictions
are based on anticipated weather and fire activity. Air quality predictions reflect only fine
particulate matter (PM2.5). If you experience health impacts from smoke, contact your
health professional. *The Air Quality Index
(AQI) values used to create the table are 24-hr averages (midnight-midnight
local time) of data from automated instruments. The data have not been
subjected to a quality assurance review.
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AQI
Category
(PM2.5 µg/m3) |
Potential
Health Impacts
|
Actions to
Protect Yourself
|
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Good
(0-12)
|
Little or
no health risk
|
None
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Moderate
(13-35)
|
Air
quality is acceptable for most. There may be moderate health concern for a
small number of sensitive people.
|
Unusually
sensitive people should consider reducing prolonged or heavy outdoor
exertion.
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Unhealthy
for Sensitive Groups – USG (36-55)
|
Members
of sensitive groups may experience health effects. The general public is not likely to be
affected.
|
People
with heart or lung disease, children and older adults should reduce prolonged
or heavy outdoor exertion. Everyone
else should limit prolonged or heavy exertion.
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Unhealthy
(56-150)
|
Everyone
may begin to experience more serious health effects.
|
The
following groups should avoid all physical outdoor activity: People with
heart or lung disease, children and older adults. Everyone else should avoid prolonged or
heavy exertion.
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Very Unhealthy
(151-250)
|
Triggers a health alert, everyone may
experience more serious health effects
|
Everyone should avoid any outdoor
exertion; people with respiratory or heart disease, the elderly and children
should remain indoors.
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Hazardous (>250)
|
The entire population is even more
likely to be affected by serious health effects.
|
The following groups should remain
indoors and keep activity levels low: People with heart or lung disease;
children and older adults. Everyone else should avoid prolonged or heavy
exertion
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