Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
“protect and enhance the quality of Nation’s air resources so as to promote the public health and
welfare……”
The critical pollutants thought to affect human health include particulate matter emitted in smoke that is
less than 10 microns in diameter (PM10). Particulates less than 10 microns are able to traverse the nose
and mouth and enter the upper airways. Due to their small size and weight, PM10 can remain airborne
for weeks. Over ninety percent of smoke particles are less than 10 microns. Wood smoke has been
documented to be mutagenic, though no direct studies have proven it carcinogenic to humans. Mutagenic
compounds cause changes to structure of a cell in ways that can be transmitted during cellular division.
This is of primary concern because mutation can be precursors for cancer. Exposure to PM10 aggravates
chronic respiratory disease such as asthma, bronchitis and emphysema.
Burning debris will release carbon dioxide and water (approximately 90 percent of total mass emitted
from the combustion process); criteria pollutants (those pollutants regulated by the EPA under the Clean
Air Act) including carbon monoxide and sulphur / nitrogen oxide; and hazardous air pollutants (also
known as “air toxins”). Air toxins include several hundred known substances including the class of
compounds known as aldehydes (formaldehyde, acetaldehyde and acrolin) and polynuclear aromatic
hydrocarbons (PAHs), several of which are known to be carcinogenic.
Research to date has yet to determine if levels of pollutants and durations of exposure from prescribed fire
operations significantly affect human health. According to sources at the Environmental Protection
Agency (EPA), particulate matter that exceeds human health standards have been measured up to three
miles downwind of prescribed burns. Studies conducted by the California Department of Health Services,
John Hopkins University and the National Institute for Occupational Safety and Health, indicate that
small but significant changes in pulmonary function occur when wildland firefighters are tested before
and after a single fire season. The exposures of wildland firefighters to CO over a full shift are generally
well below occupational health limits. However, brief (one (1) minute) peak exposures exceeding shortterm
limits of 200 parts per million of CO do occur. These limits are not to be exceeded for any period of
time.
A study of emissions in the Central Oregon area found slash burning to contribute less than 1 percent (.34
percent) of particulate matter (PM). The same study found that slash burning also produced less than One
(1) percent (.64 percent) of the carbon monoxide in Central Oregon.
Prevention of Significant Deterioration to Air Quality
The prevention of Significant Deterioration (PSD) provisions of the Clean Air Act requires measures to
preserve, protect, and enhance the air quality in national parks, national wilderness areas, national
monuments, national seashores, and other areas of special national or regional natural recreation, scenic,
or historic values.” Stringent requirements were established for areas designated as “Class 1” areas (42
U.S.C. 7475(d)(2)(B). Designation as a Class 1 area allows only very small increments of new pollution
above already existing levels. The Three Sisters Wilderness Class 1 air-shed is approximately 25 to 30
miles northwest of the northwestern end of the project area. Bend, Oregon is the closest Designated Area
(*) as defined by the Oregon State Smoke Management Plan.
* A Designated Area as defined by Oregon State smoke Management Plan is a principal population
center.
Meteorological Patterns
Weather patterns are primarily from the west and northwest during the period from April through
September. Airborne particulates matter is generally dispersed to the east and southeast during the fall
and winter months. However, tracks of lightning storms that typically result in natural ignitions typically
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