National atmospheric deposition monitoring stations have documented a reduction in sulfate deposition in the eastern United States.
Air quality monitoring networks are a significant national resource and have provided qualitative confirmation of emission-inventory estimates that indicate that pollutant emissions in the United States (and especially in urban areas) have decreased over the past three decades.
Analyses of short-term episodes with significant changes in pollutant concentrations confirm that health benefits accrue when air quality is improved.
Biomarkers may provide a useful surrogate for documenting trends in population exposure to pollutants over the longer term.
EPA’s congressionally mandated economic assessments of the costs and benefits of AQM in the United States are peer reviewed and appear to represent the state of the science.
The nation’s AQM system has not developed a comprehensive and quantitative program to track emissions and emission trends.
Although improvements have been made, accessibility to actual data acquired from the monitoring networks is limited.
The AQM system has not completed a comprehensive program to monitor HAPs so that population exposure and concentration trends can be tracked.
With the exception of CEM, there is limited ability to quantify stationary sources emissions.
The air quality monitoring network for criteria pollutants is dominated by urban sites, limiting its ability to address a number of important issues.
Some of the instruments and methods used in the nation’s air quality monitoring networks are inadequate to meet the objectives of the monitoring.
Methods used by EPA to calculate pollutant trends from data collected from air quality monitoring networks could be improved.
The AQM system has not developed a method and related program to document independently improvements in health and welfare outcomes achieved from improvements in air quality (see Box 6-8).
The AQM system has not developed a cohesive program capable of reliably reporting the status of ecosystem effects of air pollution and the response to changing air pollution conditions across regions and the nation.
Recommendations are provided in Chapter 7.