objectives. In that spirit, the committee makes five interrelated recommendations, to be implemented in concert through some 30 specific actions described in this report.

Recommendation One

Strengthen scientific and technical capacity to assess risk and track progress.

Improving the nation’s AQM system will depend heavily on reassessing and investing in relevant scientific and technical capacity to help evolve the AQM system to one that can focus on risk in priority setting and on performance in measuring progress. Without the enhancement of the nation’s scientific and technical capacity, implementation of the other four recommendations will be more difficult. The most critical actions are

  • Improve emissions tracking, including new emissions monitoring techniques and regularly updated and field-evaluated inventories.

  • Enhance air pollution monitoring, including new monitoring methods, expanded geographic coverage, improved trend analysis, and enhanced data accessibility.

  • Improve modeling, including enhanced emission and air measurement programs to provide data for model inputs and model evaluation and continued development of shared modeling resources.

  • Enhance exposure assessment, including improved techniques for measuring personal and ecosystem exposure and designing strategies to control the most significant sources of ambient, hot-spot,7 and indoor exposures.

  • Develop and implement a system to assess and monitor human health and welfare effects through the identification of indicators capable of characterizing and tracking the effects of criteria pollutants and hazardous air pollutants and the benefits of pollution control measures and their sustained use in assessments, such as the 2003 EPA Draft Report on the Environment.

  • Continue to track implementation costs by supporting the Pollution Abatement Cost and Expenditure (PACE) survey and conducting detailed


Hot spots are locales where pollutant concentrations are substantially higher than concentrations indicated by ambient outdoor monitors located in adjacent or surrounding areas. Hot spots can occur in indoor areas (for example, public buildings, schools, homes, and factories), inside vehicles (for example, cars, buses, and airplanes), and outdoor microenvironments (for example, a busy intersection, a tunnel, a depressed roadway canyon, toll plazas, truck terminals, airport aprons, or nearby one or many stationary sources). The pollutant concentrations within hot spots can vary over time depending on various factors including the emission rates, activity levels of contributing sources, and meteorological conditions.

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