INTRODUCTION


From The Changing Illinois Environment: Critical Trends,Volume 2: Air Resources, Technical Report of the Critical Trends Assessment Project

Large amounts of money have been and are being spent on pollution control efforts to protect human health and the environment. Although these efforts have had considerable benefits, many environmental goals still have not been met nationally and in Illinois. Thus, we may expect that the expenditures for environmental improvement will continue and perhaps increase.

It is incumbent upon state officials and environmental policy makers to use public funds for environmental improvement wisely. To use funds wisely in this con-text means to effect the greatest possible environmental improvement from the available resources. This implies that priorities must be set for the use of public funds for environmental improvement. What criteria should govern the setting of priorities? The U.S. EPA's Science Advisory Board (1990) stated that "policy affecting the environment must become more integrated and more focused on opportunities for environmental improvement than it has in the past. Integration in this case means that government agencies should assess the range of environmental problems of concern and then target protective efforts at the problems that seem to be the most serious."

The first step in addressing these issues is to assess the state of the environment. By executive order, Illinois' Governor Edgar directed the Department of Energy and Natural Resources (ENR) and the Governor's Science Advisory Committee (GSAC) to "conduct an environmental trends analysis and to report to the public on the state of the Illinois environment." The goals of this effort are:

1) to document techniques for searching, organizing, analyzing, interpreting, and evaluating data for geographic and temporal presentation,

2) to document assessment methodologies for analyzing environmental and human health information,

3) to identify critical data gaps, for use in prioritizing future research,

4) to establish an integrated data structure that will provide the means to judge trade-offs associated with anticipated changes in the state's natural environment or infrastructure, and

5) to produce a final report that documents past conditions and assesses the present status of the Illinois environment. Relationship of Air Resources to CTAP Project Goals

The atmospheric environment is an important component of the overall environment of the state. Weather and climate affect a broad range of ecosystem and human health issues. For example, temperature and moisture conditions and their seasonal changes determine to a great extent the geographical distribution of plant and animal species. Droughts and floods have great impacts on agriculture and transportation. Similarly, extremes of temperature and precipitation and severe weather are major hazards to human health.

Exposure to airborne contaminants also has impacts on the environment and human health, as evidenced by the use of human and environmental health as criteria in setting air pollution standards. Cases of injury to plants and human health caused by extreme concentrations of airborne pollutants are well documented in the literature.

Atmospheric deposition of airborne nutrients and contaminants is more important to ecosystem health than human health at current levels. Benefits may be realized from the atmospheric deposition of nutrients to agricultural lands, although excess nutrients in water bodies can lead to problems. Deposition of acidifying substances can lead to acidification of water bodies and ecosystem damage in certain situations.

Report Components and Structure

An assessment of the status of the atmospheric environment must include statements related to both its physical features (which over the short term we call weather, and over the long term, climate), its chemical composition, primarily as related to the concentrations of pollutants in air and precipitation, and the deposition of airborne materials back to the earth's surface. An assessment of the state of Illinois' atmospheric environment should include representations of both the spatial distributions and the time history of important features of weather and climate, as well as pollutant concentrations and deposition.

This report is composed of three major sections: Climate Trends in Illinois, Air Quality Trends in Illinois, and Atmospheric Deposition Trends in Illinois. Each presents information on the current status and temporal and spatial trends of important features of the Illinois environment, based on currently available data.

Continue to Climate Trends in Illinois