About Effects Screening Levels (ESLs)
- Guidelines for Developing ESLs, ReVs, and URFs
- What are Effects Screening Levels?
- Download the Latest ESL List (updated 2/1/13)
- Download Previous ESL Lists
What are Effects Screening Levels?
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.