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Air Trends

Special Studies

This page provides links to Special Studies topics describing policy-relevant information. These topics include analysis of Particulate Matter (PM) concentrations that will help policy makers understand sources of PM and its precursors, trends of carbon monoxide, ozone exceedances, and characterization of national spatial variation.

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  • Initial Analysis of Meteorologically Adjusted Sulfate Trend and the Implication of the Recent Economic Slowdown (PDF) (34pp, 464 KB) December 2011 - In this study, the trend of the annual 95th percentile sulfate concentrations from 2002 to 2009 has been analyzed to examine the potential influence factors that led to a significant decline in annual upper percentile sulfate concentrations. The results indicate that the major factors responsible for the accelerated sulfate decline observed in most urban areas in the US in 2008 and 2009 were: non-conducive meteorology, SO2 emission controls, and lower power demand during the economic slowdown.
  • The Multi-pollutant Report: Technical Concepts & Examples (PDF) (58pp, 2.5 MB) Revised July 2008 - This report focuses on multi-pollutant concepts as they relate to EPA's air quality management system. The purpose of this report is to facilitate a common understanding of multi-pollutant concepts to foster collaboration within and across the technical and policy disciplines of air quality management; explore multi-pollutant analytic issues; and illustrate the initial development and implementation of a technical infrastructure to support a multi-pollutant approach to air quality management.
  • Ambient Air Quality After Hurricane Katrina (PDF) (67pp, 1.3 MB) January 2008 - This report summarizes data from EPA's Air Quality System (AQS) collected in the impacted area from October 2005 through September 2006, the first year after the hurricane. These data are compared to long-term screening levels and compared to pollutant concentrations collected before the hurricane.

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