Health Impact Assessments
First, Second, and Third Tier Review of Toxic Air Pollutants
There are three levels of review
for making permit decisions about projects that emit
toxic air pollutants (TAPs):
- First Tier Review - Ecology or a local air quality agency screens the project to determine
the amount of TAPs it
- Second Tier Review - Ecology determines health impacts of the
- Third Tier Review - Ecology determines how to best manage
the health risks of the emitted TAPs
This web site is intended for those seeking information about
what to expect when they need a first, second, or third tier
review for an air
When are these different levels of analysis required?
First tier: All projects must undergo first tier review
(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.
Second tier: If a project emits more of a listed TAP than
is allowed by the Acceptable Source Impact Levels (ASIL) in Chapter 173-460 WAC,
Ecology must perform a second tier review for that TAP. This
review determines the increase in lifetime cancer risk and
other health effects for persons exposed to increased amounts
of the TAP as a result of the
proposed project. The cancer and health risks are then compared
to the maximum risk allowed by a second tier review to see if they
are within allowable limits.
Third tier: If the emissions of a TAP result in a risk
higher than allowed by the second tier review, a permit applicant may
ask Ecology to perform a third tier review. A third tier review is
a risk management decision made by Ecology. 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 benefits; and
- public input received at a public hearing, and related community feedback about the proposed facility.
What pollutants are considered TAPs?
Please refer to WAC 173-460-150 for information on the chemicals that are TAPs.
Who does the analyses?
Local air quality agencies and Ecology's regional offices routinely
perform first tier reviews. Ecology's headquarters office
performs all second and third tier reviews. Applicants must
prepare a health impact assessment (HIA) for any project subject
to second and third tier review. Ecology provides guidance on
how to prepare the HIA.
What do I submit to Ecology?
Refer to Ecology's guidance document for this information.
For more information, please contact
You can mail comments and questions to Gary Palcisko or Matt Kadlec,
Washington Department of Ecology,
P.O. Box 47600, Olympia, WA 98504-7600.
Guidance on First, Second, and Third Tier Review
Chapter 173-460 WAC, Controls For New Sources of Toxic Air Pollutants