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时间:2010-05-10 19:48来源:蓝天飞行翻译 作者:admin
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regionally significant.
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of Section 51.850, and 51.855 through 51.860 [93.150, 93.155 through 93.160]. In other words,
a conformity determination will be required. See 40 C.F. R. Section 51.853 (i) & (j) [93.153 (i)
& (j)]. See Section Five for more information on General Conformity.
To determine conformity, applicable pollutant concentrations are computed by dispersion
modeling, combined with background pollutant concentrations, and compared with NAAQS for
exceedance. If pollutant concentrations do not exceed the NAAQS, the action conforms. If
NAAQS are exceeded, two alternatives apply: The action can be demonstrated to conform by
coordinating an alternative conformity determination with the local, State, and EPA
representatives, or the Federal action can be mitigated, offset, or redesigned to reduce overall
emissions. See Section Five for more information on General Conformity.
Determination that a Federal action conforms with the applicable implementation plan does not
exempt the action from meeting other requirements of the applicable implementation, NEPA or
the CAA. If both an environmental document and a conformity document are required, the
conformity documentation or procedures can be combined with the environmental document or
procedures (e.g., the conformity determination can be included in an Environmental Impact
Statement, or public notices can be combined), or the documents can be prepared separately.
2.1.5 NAAQS Assessment
Air quality is assessed based on a comparison of the NAAQS for each criteria pollutant with the
projected pollutant concentrations at the airport or air base. To determine whether the NAAQS
must be assessed, the Federal agency first must consider whether the action is an advisory,
emergency, or excluded activity. Some Federal actions are advisory in nature (e.g., an airspace
determination) and do not require an air quality impact analysis or documentation. An
emergency action is an action undertaken in the case of an emergency, disaster, or other similar
great urgency. Categorically excluded activities do not individually or cumulatively have a
significant effect on the human environment based on agency experience (e.g., issuance of
airport planning grants) and do not require preparation of an environmental document. Lists of
specific advisory, emergency, and excluded activities are provided in the FAA Order 1050.1 and
5050.4 and/or the USAF EIAP: Desk Reference. If the action is an advisory, emergency , or
excluded activity, no further action is required.
If the action is not an advisory, emergency, or an excluded activity, screening techniques are used
to evaluate whether performing an NAAQS assessment should be considered. If the action is in
a nonattainment or maintenance area and exempt or presumed to conform under conformity
requirements, it is assumed that a NAAQS assessment is not required for an airport or air base
action (since it is unlikely the action’s pollutant concentrations would exceed the NAAQS). If the
action is in a nonattainment or maintenance area, but it is not exempt or presumed to conform,
the screening technique (based on passengers and operations) outlined in the threshold analysis
discussion following should applied. If the action is in an attainment area, this screening
technique also should be applied. See the threshold analysis discussion following for more
information.
If a NAAQS assessment is needed, the airport’s or air base’s “build” and “no-build” emissions
are inventoried for each reasonable alternative. The inventory should include both direct and
indirect emissions (see section 3 for a more thorough discussion). For this analysis, indirect
emissions are not limited to those that the Federal agency can practicably control (as under
conformity). The airport’s or air base’s emissions for the proposed build case then are translated
into pollutant concentrations using a dispersion model. This step is very data and computation
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intensive and may need to be performed for both “general” airport pollutant concentrations
and/or intersection pollutant concentrations.
Assessing NAAQS for “general” airport concentrations requires identifying all emission sources
at the airport or air base by individual location, quantifying their peak and temporal emission
rates, analyzing the emissions in the context of local weather (which could include hourly
conditions of a year or more), and determining the resulting pollutant concentration at receptor
sites in the vicinity of the airport.
If congestion increases at off-airport or air base highway intersections due to increased traffic
coming to the airport or air base due to an airport/air base action, CO emissions may exceed the
 
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本文链接地址:Air Quality Handbook航空质量手册(17)