The 1990 amendments to the Clean Air Act (CAA) present a list of 188 Hazardous Air Pollutants (HAPs) of which mercury is one. The CAA requires the US Environmental Protection Agency (EPA) to identify HAP sources, quantify the emissions by source category, develop regulations for each source category, and assess the public health and environmental impacts after regulations are implemented. The various needs for air toxic data cover major, area, and mobile sources, and include estimates of emissions at the national, regional, county, and facility-specific levels, and even down to process-specific emission data for modelers.
In 1993, EPA began developing the National Toxics Inventory (NTI), a national repository of emission inventory data for HAPs. The 1996 NTI is a model-ready emissions inventory for use in dispersion and exposure modeling that not only can be used to predict ambient air concentrations and resultant risk to the American population, but will also be used to measure progress under the CAA in reducing HAP emissions. The 1996 NTI has recently been compiled with estimates of the 188 HAPs. It will be used as the base year for comprehensive, facility-specific HAP emissions data and source-specific parameters. NTI contains estimates of emissions from major sources, area sources, and onroad and nonroad mobile sources. Subsequent NTIs will be created every three years.
|Document Type:||Background paper|