How the STAR Program Works

The STAR Program was officially implemented by a set of regulations adopted by the Louisville Metro Air Pollution Control Board on June 21, 2005. There are three key components of the STAR Program that were created to address different categories of sources contributing to toxic air pollution.

  • The first component lists all toxic air contaminants (TACs) covered by the program, establishes the overall framework and methodologies for determining risk from TACs, and institutes a general duty not to emit any TAC in a quantity or duration that is harmful to the health and welfare of humans, animals, and plants. (See Regulations 5.01 and 5.23).
  • The second component addresses large and moderate industrial and commercial operations, which are responsible for the largest, single-source emissions of most toxic air pollutants. It required companies that emit the largest amounts of chemicals to determine through modeling whether they were exceeding the health risk goal for each of the targeted chemicals. If they exceeded any health risk goal, they were required to present a plan to reduce emissions in order to reach goal over the following six years. At the time it was passed, this aspect of the STAR Program primarily affected 170 companies of Louisville’s 32,000 businesses. (See Regulations 5.215.20 and 5.22, and Technical FAQ for Regulations 5.20, 5.21, and 5.22)
  • The third component of the STAR Program was adopted in recognition that large and moderate industrial and commercial operations are not the only sources of toxic air pollution, and covers the myriad of smaller sources of air toxics emissions. It required the District to submit a Report and Plan of Action to assess and address the risk to human health and welfare from ambient air concentrations of TACs from minor stationary sources, area sources, non-road mobile sources, and mobile sources. (See Regulation 5.30, Regulation 5.30 Report and Plan of Action).

The APCD continues to implement STAR through the regular inspection of sources and re-review of STAR conditions when permits are renewed. Any new facilities or equipment, including any built since July 1, 2005, will be subject to a cumulative emissions goal that is half that of sources that were already is existence when STAR was passed. 


The full list of pollutants that are regulated through STAR can be found in Regulation 5.23. Below are Category 1 and Category 2 TACs, which were compounds of the highest concern at the time that STAR was adopted.

The compounds below are Category 1 TACs, which are 17 compounds that were monitored at levels that could cause an unnacceptably high risk of cancer during the West Louisville Air Toxics Study:

Acrylonitrile Arsenic Benzene Bromoform 1,3 Butadiene
Cadmium Carbon Tetrachloride Chloroform Chloroprene Chromium
1,4 Dichlorobenzene Formaldehyde Methyl Chloride Nickel Tetrachloroethylene
Trichloroethylene Vinyl Chloride      

Sources with the largest emissions of these 17 chemicals were required to report information to the Louisville Metro Air Pollution Control District starting April 2006, and were required to meet emissions goals or prove that they were using best available technology to lower emissions by 2011.

The compounds below are Category 2 TACs, which are 19 compounds not included as Category 1 TACs that have an EPA Risk-Screening Environmental Indicators (RSEI) Full Model Relative Risk Score equal to or greater than 500 based on the 2002 Toxics Release Inventory (TRI) reported air emissions for Jefferson County.

Aluminum Chlorine Glycol ethers Manganese & its compounds
Ammonia Cobalt & its compounds Hydrochloric acid Naphthalene
Boron trifluoride Copper & its compounds Hydrofluoric acid Nitric acid
Butyl acrylate Diisocyanates Lead compounds Sulfuric acid
Toluene 1,2,4 Trimethylbenzene (cumene) Xylene (mixed isomers)  


Requirements of Sources

Sources of toxic emissions annually provide the APCD aggregate data on toxic chemicals used in their operations.

Emissions Inventory: Companies will provide detailed information to the APCD and the public about the amount of each of the targeted toxic chemicals they release.

Emissions Levels by Point of Release: Companies will provide detailed information about the emissions levels of toxic chemicals from each stack or release point in their facility. The report will list the amounts of each chemical from each stack or release point.

Emissions Level Modeling: Companies will use established models to determine whether any of the chemicals they are using exceed the health risk goal. If toxic chemical emissions are at levels below the goal, no additional action is required.

Emissions Reduction Plan: If toxic chemical emissions exceed the health risk goal, companies must submit a plan to the APCD staff for lowering emissions to meet the goal. Steps could include changing to less toxic chemicals, using lesser amounts of toxic chemicals, improving processes to reduce emissions levels.

Emissions Compliance: Companies must meet the health risk goal for each toxic chemical within the specified timeframe or prove to the APCD Board – A) they have made significant progress and deserve more time to meet the goal or B) they have implemented the best technology available to reduce emissions.

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