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About Effects Screening Levels (ESLs)

Information about ESLs used in the review of air permitting data, ESL Lists and links to the lists.

Effects Screening Levels are screening levels used in TCEQ’s air permitting process to evaluate air dispersion modeling’s predicted impacts. They are used to evaluate the potential for effects to occur as a result of exposure to concentrations of constituents in the air. ESLs are based on data concerning health effects, the potential for odors to be a nuisance, and effects on vegetation. They are not ambient air standards. If predicted airborne levels of a constituent do not exceed the screening level, adverse health or welfare effects are not expected. If predicted ambient levels of constituents in air exceed the screening levels, it does not necessarily indicate a problem but rather triggers a review in more depth.

Both short- and long-term ESLs are listed on the ESL List. “Short-term” generally indicates a one-hour averaging period. Exceptions are noted parenthetically after a constituent name. “Long-term” indicates an annual averaging period.

About the TCEQ Toxicity Factor Database

The Toxicity Factor Database is now a part of Texas Air Monitoring Information System (TAMIS) database. This database is a one-stop-shop for information about all toxicity factors developed by the TCEQ. If you previously used Excel spreadsheets to access the toxicity factors, you will now access them via the TAMIS database.

The TAMIS database includes not only Effects Screening Levels (ESLs), but also Air Monitoring Comparison Values (AMCVs) and their supporting documentation. The TCEQ created the database in order to reduce errors, improve database structure, provide more information and detail to our customers, and allow more dynamic and efficient data entry.

Learn more about the Toxicity Factor Database and query the Toxicity Factor Database to search for AMCVs.

Special Notations for the Toxicity Factor Database ESLs

This interoffice memorandum provides important information (notations and exceptions) to users on use of ESLs in air permitting. Exceptions provided in the document include how to evaluate a compound designated with PM, as well as exceptions to the 1-hr averaging period. This memorandum was previously provided with the ESL Published Lists under the Cover Memo tab. With the new Toxicity Factor Database, this memorandum will now be housed here for reference.