A.S.L. & Associates over the past 27 years has developed extensive experience and resources for the purpose of assessing the potential impacts of air pollution on the environment. Corporate clients include major industrial, environmental, and governmental groups in the United States and Canada. The Company's President and Founder, Dr. Allen S. Lefohn, has focused the Corporation on those environmental issues that directly link pollutant exposure with biological effects.

A.S.L. & Associates is unique in its approach toward developing solutions to complex issues. The company teams with leading scientists from around the world to focus on complex scientific issues. Mainframe and microcomputer software assist the firm in performing statistical and characterization analyses. Results are easily presented in GIS, as well as other creative visual summaries. Because our research is cutting edge, more than 90% of our results are published in the peer-reviewed literature. Dr. Lefohn and his associates have established an outstanding reputation for providing research and analyses in several major areas. Some of these research areas are

Standard-Setting Evaluations

• The evaluation of the limitations associated with exposure models that relate to risk assessment methodologies.
• The evaluation of the strengths and weaknesses associated with epidemiological methodology and the standard-setting process.
• The evaluation of PM2.5 and ozone data for assessing one of the key assumptions in epidemiological assessments that spatial variability does not exist.
• The evaluation and assessment of ambient air quality standards and critical levels/loads.
• The evaluation and assessment of using the W126 cumulative ozone exposure index as a secondary standard to protect vegetation.
• Developing rollback models for assessing alternative risk scenarios for federal government air pollution rulemaking processes.
• Developing the scientific rationale for explaining the "piston" effect.
• The identification of areas in the United States that violate Federal ozone, PM-2.5, and other criteria pollutant standards.
• Characterizing policy-relevant and natural background ozone levels and their relationship to the standard-setting process.
• Evaluating the occurrences of elevated short-term 5-minute SO2 average concentrations in the U.S.
• The evaluation of mathematical models that relate short-term 5-minute SO2 concentrations with hourly average concentrations.

Human Health Effects

• Evaluating the relationship between epidemiological results and ambient air quality data.
• The evaluation of the statistical methodology associated with epidemiological studies relating air pollution to human health effects.
• The evaluation of ambient air quality exposures in relationship to biological effects.
• The design of ozone hourly average concentration exposure regimes that mimic ambient concentrations for use in controlled human-health clinical experiments.
• The integration of dose-response human health data with ambient exposure for the purposes of evaluating current and future forms and levels of air quality standards.
• The applicability of Haber's Law (concentration times duration) in assessing possible human health effects.

Vegetation Effects

• The development of vegetation and human health exposure-response relationships.
• Explore the efficacy of various defense mechanisms for helping to define "effective" dose.
• The development of a bridge that allow for the use of exposure-response and dose-response data for predicting vegetation effects.
• Explore the efficacy of applying the U.S. 8-hour ozone standard to protect forests and agricultural crops.
• Identify "areas of concern" for areas that may be impacted by ozone exposures for forests in North Carolina, Tennessee, and South Carolina.
• Summarize ozone exposures that may have an effect on vegetation grown in the Southern Appalachian region of the United States.
• Summarize the state-of-knowledge for the U.S. EPA of the status of the use of relevant exposure indices for predicting ozone effects on vegetation (Chapter 9 of the EPA's 2006 Ozone Criteria Document).
• Develop exposure-response relationships for tree seedlings using data from five intensive Southern Commercial Forest Research Cooperatives.
• The design of vegetation air pollution exposure studies that mimic ambient conditions.
• Application of geographic information system (GIS) approaches that integrate vegetation effects with exposure information.

Air Quality Characterizations

• The application of mathematical interpolation techniques (e.g., kriging) to predict ozone exposures across the United States.
• The identification of clean sites in the United States and other parts in the world that can serve as indicators of natural background for surface ozone and other pollutants.
• The identification of clean site in the United States that can serve as indicators of natural background for particulate matter.
• Summarize the state-of-science for the National Acid Precipitation Assessment Program (NAPAP) for the air quality characterization of agricultural and forested areas for vegetation effects purposes.
• Summarize the state-of-knowledge for the U.S. EPA of the air quality characterization of ozone for urban and rural areas for health and vegetation effects purposes (Chapter 4 of the 1996 Ozone Criteria Document and Chapter 3 of the 2006 Ozone Criteria Document).
• The development of scientifically defensible approaches to predict ozone levels as a function of emission reductions (i.e., rollback methods).
• Determine trends of ozone exposures in the United States.
• The characterization of air pollution co-occurrences under ambient conditions for designing human health and vegetation exposure experiments.
• Defining air quality characterization in biologically meaningful terms.
• Develop a global sulfur emissions inventory for purposes of the development of global climate models.

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