National Air Toxics Assessment (NATA)

The 1990 amendments to the Clean Air Act (CAA) require the U.S. EPA to identify sources, quantify emissions, develop regulations, and assess public health and environmental impacts of toxic air pollutants, as well as put regulations into effect for the 188 air toxics.

NATA is the National-Scale Air Toxics Assessment which the U.S. EPA developed to model exposure to 32 air toxics (a subset of the 188 air toxics) plus diesel particulate matter (diesel PM). These pollutants present the greatest threat to public health in the largest number of urban areas. The results of the national-scale assessment will provide important information to help EPA continue to develop and implement an appropriate and effective national air toxics program.

The objectives of the program are:

  1. Identify air toxics which are of greatest potential concern.
  2. Characterize the types, concentrations and amounts of air toxics that come from various emissions sources and the populations they affect.
  3. Set priorities for the collection of additional air toxics data and research to improve estimates of air toxics concentrations and their potential public health impacts.
  4. Improving national - and local - scale modeling, including tracking trends of modeled ambient concentrations of air toxics.
  5. Establish guidelines to meet the goals of reducing the inhalation risk of ambient air toxics, and establish a baseline in which to measure the progress being made toward attaining those goals.