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Air Quality in Indiana

Air Quality in Indiana > Air Quality 101 Air Quality 101

July 2014: Progress in Air Quality Levels?

Our office makes a quarterly assessment on what percent of Hoosiers breathe clean air. If looked at over the last four years, it appears that we are going backwards. In 2009 the entire state of Indiana met all national ambient air quality standards. Now we have areas that are not meeting the standards for lead, ozone and sulfur dioxide. What happened? Well the air quality is not getting worse—we are continuing to make progress. In all cases, either new standards were issued or existing standards were tightened by the United States Environmental Protection Agency (U.S. EPA). The result of this is that we now have areas that are not meeting current standards.

The best way to illustrate this is to select an area and show how the data has changed. I grew up in Vigo County so I have selected it as our test case. Table 1 shows the ozone levels for recent periods and compares them to the standard in place for the period. For all pollutants, attainment of the standard is demonstrated by comparing a three year average with the appropriate standard. Ozone levels are measured in parts per billion (ppb).

Table 1: Ozone Levels in Vigo County (ppb)
Years 2000 - 2002 2001 - 2003 2002 - 2004 2003 - 2005 2004 - 2006 2005 - 2007 2006 - 2008 2007 - 2009 2008 - 2010 2009 - 2011 2010 - 2012 2011 - 2013
Design Value * 91 87 83 76 73 73 70 66 63 64 66 67
Standard 84 84 84 84 84 84 84 84 75 75 75 75

* For more information on "Design Value" see the Air Quality 101 article for April, 2014 or the U.S. EPA Design Values webpage.

The key here is that although the standard was tightened, ozone levels have continued to decrease such that the area remains in attainment for ozone.

Table 2 shows similar data for PM-2.5 (particulate matter with a diameter less than 2.5 microns). For this pollutant there are two standards, a daily standard and an annual standard. Although the standards for both time periods have decreased, the measured levels have continued to drop such that the area remains in attainment for PM-2.5. PM-2.5 levels are measured in micrograms per cubic meter (ug/m3).

Table 2: PM-2.5 Levels in Vigo County (ug/m3)
Years 2000 - 2002 2001 - 2003 2002 - 2004 2003 - 2005 2004 - 2006 2005 - 2007 2006 - 2008 2007 - 2009 2008 - 2010 2009 - 2011 2010 - 2012 2011 - 2013
Design Value * 38 38 35 36 34 35 30 27 27 27 27 25
Standard 65 65 65 65 65 65 65 35 35 35 35 35
Annual Design Value * 15.2 14.6 13.8 14.1 13.7 14.2 13.2 12.8 12.4 12.4 11.9 11.1
Standard 15 15 15 15 15 15 15 15 15 15 12 12

* For more information on "Design Value" see the Air Quality 101 article for April, 2014 or the U.S. EPA Design Values webpage.

Table 3 shows 1-hour sulfur dioxide (SO2) levels in Vigo County. These levels are measured in parts per billion (ppb). Values have reduced a little since 2000. However, the standard only became effective in 2010. The source that is contributing to these levels is required to meet the standard by 2017. At that time levels will drop below the standard.

Table 3: Sulfur Dioxide Levels in Vigo County (ppb)
Years 2000 - 2002 2001 - 2003 2002 - 2004 2003 - 2005 2004 - 2006 2005 - 2007 2006 - 2008 2007 - 2009 2008 - 2010 2009 - 2011 2010 - 2012 2011 - 2013
Design Value * 159 159 135 138 125 125 125 137 149 150 145 123
Standard NA NA NA NA NA NA NA NA NA NA 75 75

* For more information on "Design Value" see the Air Quality 101 article for April, 2014 or the U.S. EPA Design Values webpage.

The message is that while we have recently added people living in parts of Vigo County as not breathing clean air, the levels are not getting worse. They have been added because U.S. EPA finalized a new 1-hour SO2 standard. There is a plan being developed that should bring the area back into attainment by 2017.

Comments can be sent to me at kbaugues@idem.in.gov.

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