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IDEM’s Hazardous Air Pollutant (HAP) emissions inventory includes estimates or reported data for hazardous air pollutants for point, area, and mobile sources. These data are used to support various efforts, including the National Air Toxics Assessment (NATA), U.S. EPA risk and technology reviews, and regional and local scale air quality modeling.
IDEM's HAP emissions inventory includes pollutants from the 1990 Clean Air Act (CAA) Amendment's HAPS list.
The geographic area of IDEMs HAPs inventory is statewide. The point sources included in the HAPs inventory are coded to a certain geographic point using county, city, address, zip code, and Universal Transverse Mercator (UTM), or latitude and longitude coordinates. Area and mobile source estimates are compiled at the county level and apportioned accordingly in modeling studies.
The HAPs inventory has been evolving since its inception in the mid 1990s. Initial HAP inventories were more limited in scope due to available knowledge, information, and resources. Improvements in HAP emissions estimating techniques and available information have resulted in improved estimates today, but quality data is still lacking in many cases. Changes in criteria pollutant reporting requirements have resulted in a complete HAP inventory every three years.
Sources within the state are required to report emissions of criteria pollutants on a regular interval. IDEM asks that sources voluntarily report their HAP emissions at those times, though it is not required. If HAPs emissions data are needed for a specific purpose IDEM has the authority under 326 IAC 2-6-5 to require certain emissions data from a source to aid in completion of that specific project.
The IDEM website provides more information about the voluntary reporting of HAPs emissions data.
Sources for which IDEM collects HAP emissions information fall into three categories:
Learn more about Hazardous Air Pollutants.