Use of Meteorology in Air Quality Regulatory Programs

State Implementation Plans (SIPs) are federally approved plans developed by state (or local) air quality management authorities to attain and maintain the National Ambient Air Quality Standards. Generally, these SIPs are a state s (local) air quality rules and regulations that are considered an acceptable control strategy once approved by the USEPA. The purpose of SIPs is to control the amoimt and types of pollution for any given area or region of the United States. 

In these types of control strategies, emission limits should be based on ambient pollutant concentration estimates for the averaging time that results in the most stringent control requirements. In all cases, these concentration estimates are assumed to be the sum of the pollutant concentrations contributed by the source and an appropriate background concentration. An air quality model is used to determine which averaging time (e.g., annual, 24-hour, 8-hour, 3-hour, 1-hour) results in the highest ambient impact. For 

This section is adapted from USEPA, Basic Air Pollution Meteorology, U.S. Environmental Protection Agency, Washington, DC, 2005 (www.epa.gov/apti). 

Ozone is not emitted by industrial sources it is formed by volatile organic chemicals (VOCs) and nitrogen oxides (known as ozone precursors) in the presence of heat and sunlight. VOCs emissions are regulated as a surrogate for ozone. 

Air quality modeling is necessary to ensure that a source is in compliance with the SIP and New Source Review requirements. When air quality modeling is required, the selection of a model is dependent on the source characteristics, pollutants emitted, terrain, and meteorological parameters. The USEPA s Guideline on Air Quality Modeling (40 CFR 1, Appendix W) summarizes the available models, techniques, and guidance in conducting air 

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