This report presents a summary of air quality data collected throughout the State of Illinois during the calendar year - 2002. Data is presented for the six criteria pollutants (those for which air quality standards have been developed - particulate matter (PM10 and PM2.5), ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead) along with some heavy metals, nitrates, sulfates, and volatile organic compounds. Monitoring was conducted at over 90 different site locations collecting data from more than 200 instruments. In terms of the Air Quality Index (AQI) air quality during 2002 was either good or moderate more than 89% of the time throughout Illinois. There were 4 days (all due to ozone) when air quality in some part of Illinois was considered Unhealthy (category Red). Additionally, there were 34 days (30 for 8-hour ozone and 11 for PM2.5, 7 days were high for both ozone and PM2.5) when air quality in some part of Illinois was considered Unhealthy for Sensitive Groups (category Orange). This compares with 40 Unhealthy for Sensitive Groups days in 2001. The increase in unhealthy ozone days (34 in 2002 versus 17 in 2001) is primarily due to 2002 being more conducive than normal in terms of weather patterns associated with elevated ozone than an indication of worsening air quality. Air quality trends for the criteria pollutants are continuing to show downward trends or stable trends well below the level of the standards. Percentage changes over the ten year period 1993 2002 are as follows: Particulate Matter (PM10) 11% decrease, Sulfur Dioxide 31% decrease, Nitrogen Dioxide 4% decrease, Carbon Monoxide 44% decrease, Lead 53% decrease, and Ozone 6% decrease. Stationary point source emission data has again been included. The data in the report reflects information contained in the Emission Inventory System (EIS) as of December 31, 2002. Emission estimates are for the calendar year 2001 and are for the pollutants: particulate matter, volatile organic material, sulfur dioxide, nitrogen oxides and carbon monoxide. Emission trends of these pollutants has been given for the years 1981 to the present. Emissions reported with the Annual Emissions Report have been provided starting with 1992. In general there has been a trend toward decreasing emissions over this time period.