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Program Template photo identifier

Air Quality Program

Health Impact Assessments
First, Second, and Third Tier Review of Toxic Air Pollutants

A picture of a factory.

There are three levels of review for making permit decisions about projects that emit toxic air pollutants (TAPs):

  1. First Tier Review - Ecology or a local air quality agency screens the project to determine the amount of TAPs it will emit
  2. Second Tier Review - Ecology determines health impacts of the emitted TAPs
  3. 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 quality permit.


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.

More 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.

Related links

Guidance on First, Second, and Third Tier Review

Chapter 173-460 WAC, Controls For New Sources of Toxic Air Pollutants


Application for Second Tier or Third Tier Review

Guidance on First, Second, and Third Tier Review

Chapter 173-460 WAC, Controls For New Sources of Toxic Air Pollutants

WAC 173-460-150, Table of Acceptable Source Impact Levels, Small Quantity Emission Rates, and De Minimis Emission Values


Quincy Data Center


Updating New Source Review Fees in Chapter 173-455 WAC