Air Quality >
Tier II Analysis Information
Tier II Analysis Information
This web site is intended for those seeking information about
what to expect when they need a Tier II Analysis for an air
quality permit.
What is Tier II Analysis?
Tier II Analysis is the second of three levels of review
done in making permit decisions for projects that emit
toxic air pollutants (TAPs):
1) Tier One - Ecology or a local air quality agency screens the project to determine if it
will emit TAPs
2) Tier II - Ecology determines health impacts of the
emitted TAPs
3) Tier Three - Ecology determines how to best manage
the health risks of the emitted TAPs
When are these different levels of analysis required?
Tier I: All projects must undergo Tier I Analysis
(toxic screening) before getting a permit. This is
required by WAC 173-460-040. The purpose of the toxic
screening is to control emissions of TAPs from new sources in
order to prevent air pollution, reduce TAP emissions as much as
possible, and maintain healthy and safe air quality.
Tier II: If a project emits more of a listed TAP than
is allowed by the Acceptable Source Impact Levels (ASIL) in Chapter 173-460 WAC
( http://apps.leg.wa.gov/WAC/default.aspx?cite
), Ecology must perform a Tier II Analysis. This
analysis determines the increase in lifetime cancer risk and
other health effects for persons exposed to increased amounts
of a TAP as a result of the
proposed project. The cancer and health risks are then compared
to the maximum risk allowed by a Tier II Analysis to see if they
are within allowable limits.
Tier III: If the emissions of a TAP result in a risk
higher than allowed by the Tier II Analysis, a permit applicant may
ask Ecology to perform a Tier III analysis. A Tier III
Anaysis is
basically a risk management decision. Ecology's Director
decides whether the risk of the
project is acceptable based on:
- whether Ecology determined that available preventive
measures can reduce emissions enough to protect human health;
- estimated environmental effects; and
- public input received at a
public hearing, and related community feedback about the
proposed facility.
What pollutants are considered TAPs?
Here is a link to a
consolidated list of TAPs. Please see sections 150 and
160 of
Chapter 173-460 WAC for more complete information about
chemicals that are TAPs.
Who does the analyses?
Local air quality agencies routinely do Tier I Analyses.
However, only Ecology does Tier II and III Analyses.
Please note:
For more information please contact Richard B. Hibbard at
rhib461@ecy.wa.gov or (360) 407-6896. Comments can be mailed to
the indicated Ecology contact, Washington Department of Ecology,
P.O. Box 47600, Olympia, WA 98504-7600.
Related Links
Tier II Analysis Applications Received
Tier II Analysis' open for
Public Comment
Tier II Completed Analysis'
