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In the next year, the United States Environmental Protection Agency (U.S. EPA) will be proposing a new ozone standard. The current standard is 75 parts per billion (ppb). The range that U.S. EPA is considering is from 60 to 70 ppb. Where they select the final standard is very important to Indiana and many other states. Compliance with the standard is determined by estimating a design value for the latest three years. The following data shows the Indiana design values for the period 2011–2013 and where each county would fall depending upon what standard is selected.
Right now, we have four counties that do not meet the current 8-hour ozone standard. If the standard is lowered to 70 ppb, we will have 11 counties that will not meet the standard. If the standard is lowered to 65 ppb, we will have 25 counties that will not meet the standard. If the standard is lowered to 60 ppb, all 29 counties where we measure ozone will not meet the standard. The actual designations will not be based upon data for the 2011–2013 period; it may be 2013–2015 or 2014–2016. So, if ozone levels continue to decrease, we may have several counties that will attain the standard that are not currently shown to. The key is whether we have hot summer days during the next two to three summers. If we do, Indiana could have much of the state designated as nonattainment for the new 8-hour ozone standard.
As the standard is lowered, the issue of how clean is the air entering a state arises. Indiana has placed an ozone monitor in eastern Illinois (West Union) to determine the levels of ozone as the air enters Indiana. In the Indiana county just east of this location (Vigo County), we have two ozone monitors. In looking at ozone levels at or above 65 ppb in 2011, the average ozone level blowing in from Illinois was 53 ppb. This leaves very little room for Indiana to meet the standard. Looking at the same data for 2012, however, shows a different situation. On days with an ozone level of 65 ppb or greater, the level entering Indiana was only 27 ppb. Data for 2013 for the Vigo County sites had no days above 65 ppb. We will continue to look at this data in the future to see whether we have an issue with incoming air or not.
Interesting times are ahead.