This section presents information about recent trends in PM2.5 emissions from the national to the project level; and future PM2.5 pollutant burden estimates for the northeastern Illinois region.
EPA's December 2004 "Particle Pollution Report: Current Understanding of Air Quality and Emissions through 2003" states that PM2.5 emissions have dropped nationwide by 10% from 1999-2003. During that time, in the Industrial Midwest states, including Illinois, PM2.5 emissions have dropped by 9%. The most current national PM2.5 trend data from EPA, shown in Figure 5, indicates that as of 2006 levels have decreased by 15% from 1999. Note that national 2005 PM2.5 monitor data exhibits the same anomalous spike as does Illinois 2005 PM2.5 monitor data.Figure 5 - PM2.5 Air Quality 1999 - 2006
According to EPA, the 2007 heavy-duty engine standards will result in the introduction of new, highly effective control technologies for heavy-duty engines, beginning in 2007. Heavy-Duty trucks and buses currently account for approximately one-quarter of mobile source PM emissions. These new standards will result in PM emission levels 95% below today's levels. By addressing diesel fuel and engines together as a single system, this program will provide annual emission reductions equivalent to removing the pollution from more than 90% of today's trucks and buses, or about 13 million trucks and buses, when the current heavy-duty vehicle fleet has been completely replaced by 2030. By 2030, this program is expected to reduce annual emissions of PM by 110,000 tons.
Recent trends in PM2.5 levels throughout the State of Illinois including Kane, Kendall and Will, counties were available in the "Illinois Annual Air Quality Report, 2005". For the State, in terms of the Air Quality Index (AQI) during 2005, there were 32 days (13 for PM2.5) when air quality in some part of Illinois was considered "Unhealthy for Sensitive Groups". This compares to seven days (all PM2.5) in 2004 and 19 days (8 for PM2.5) in 2003. Throughout the state monitoring was conducted at 38 stations for PM2.5. Valid annual averages (meeting minimum statistical selection criteria) were obtained for 36 of the 38 sites. Twenty-two stations recorded averages above 15.0 μg/m3, the level of the annual standard, compared with 6 stations in 2004 and 9 stations in 2003. The Statewide average of annual averages was 15.5 μg/m3 in 2005 compared with 12.5 μg/m3 in 2004 and 14.1 μg/m3 in 2003. The trend of the statewide annual averages for PM2.5 for the period 2000-2005 is shown in Figure 6. There were no exceedances of the 24-hour standard of 65 μg/m3 in 2005. The Statewide peak in 2005 of 62.6 μg/m3 was recorded at the Chicago Mayfair station located on the north side of Chicago. The Statewide average of the 98th percentile of 24-hour averages was 42.1 μg/m3 in 2005 compared with 30.9 μg/m3 in 2004 and 34.1 μg/m3 in 2003.Figure 6 - Illinois Statewide PM2.5 Trends
The CATS October 2006, PM2.5 conformity assessment, using EPA's MOBILE6.2 mobile source emission factor model, estimated that direct on-road mobile source PM2.5 annual emissions for the northeastern Illinois PM2.5 nonattainment area would decrease by 37% between 2010 and 2030, the period when this project could reasonably be anticipated to be open to traffic. Over this same time period, annual vehicle miles of travel are expected to increase by 15%. These data are summarized in Table 5.
The Dan Ryan is the most heavily traveled expressway in the Chicago region. In 2005, at the start of reconstruction, average daily traffic levels were between 230,000 and 300,000 and the number of daily heavy commercial vehicles ranged from 22,000 to 29,000. In conjunction with the Dan Ryan Expressway reconstruction project, IDOT monitored air quality prior to and during the entire reconstruction period. Baseline PM2.5 monitor data were collected from September 2004 through the end of the year. Monitoring of the construction phase began in January 2005 and ended October 31, 2007. PM2.5 monitoring locations were established in the area bounded by Cottage Grove Avenue on the east, Halsted Street on the west, 23rd Street on the north and 103rd Street on the south. In 2005 there was one elevated reading. This occurred on June 28, 2005, which was an Air Pollution Action day. On this day the entire Chicago region was experiencing poor air quality and thus the elevated PM2.5 levels were attributed to a regional air quality issue and not a project level issue caused by the Dan Ryan. In 2006, one monitor recorded an elevated reading on October 21. No other monitors registered elevated readings on this day and no particular event or condition could be identified as the cause. These readings are not individually relatable to the PM2.5 NAAQS. The readings are individual data points. The PM2.5 standard is based on a 3-year average of the 98th percentile of 24-hour concentrations.