Citation:

Impact/Purpose:

This document presents a screening-level, risk-based ranking of pollutants indoors as part of the overall EPA National Air Toxics Program (NATP). The ranking was performed so that we could prioritize our efforts on indoor air toxics. There are thousands of chemicals found in the indoor environment, and we cannot adequately address the risks and risk reduction activities for all of these pollutants. The ranking analysis allows us to focus our efforts on those indoor pollutants that may present a greater risk indoors, based on the available data, and will allow us to focus our risk reduction efforts on the greatest opportunities for reducing risks through voluntary, non- regulatory risk management approaches.

Description:

The basis of the ranking is 10 monitoring studies chosen to represent "typical" concentrations of the pollutants found indoors. The studies were conducted in the United States during the last 15 years, and mainly focused on concentrations of pollutants in homes, schools, and office buildings. Some of the data are from recent analyses performed by EPA in 100 office buildings and several schools, using the EPA Building Assessment Survey and Evaluation (BASE) protocol. The other data are from additional EPA studies, as well as studies by organizations outside of EPA (e.g. the California Air Resources Board and Bell Communications Research). The data span a broad range of chemicals, and include data for metals, aldehydes, volatile organic compounds (VOCs), and semi-volatile organic compounds (e.g., pesticides, phthalates, and polyaromatic hydrocarbons). These data are combined with health-based indices (i.e., risk-based concentrations, or RBCs, as defined in the Technical Support Document for the National Air Toxics Program/Urban Air Toxics Strategy) to obtain ranking scores for both acute and chronic effects.

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