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Four Highest Eight-Hour Ozone Concentrations in 2021
as of February 26

Use this form to retrieve the four highest eight-hour ozone concentration averages from data collected at IDEM monitoring sites beginning December 14, 2005 through today. Although this is our most current data, it is not considered official until it has been certified by our technical staff. This information is updated hourly. All times shown are in Local Standard Time.

The table below lists the four highest daily maximum eight-hour ozone concentrations measured in 2021 in each community where the IDEM measures ozone. Concentrations that are rated Moderate or higher are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) The fourth-highest average is in bold black (unless it is highlighted). All ozone measurements are in parts per billion. Times are shown in 24-hour format and correspond to the beginning of the eight hour average.

Use the selection boxes below to customize this report. You may select a different year or a different report format. If you want to cut and paste data from this web page into another application, such as a spreadsheet, select the comma-delimited format. Click on the Generate Report button once you have made your selections.

YearReport Format
Highlight with AQI colors
Area Monitoring Site POC Highest Second Highest Third Highest Fourth Highest
Date Time Value Date Time Value Date Time Value Date Time Value
North West
Hammond-141st St102/21/202110004902/22/202101004502/20/202110004401/31/2021150041
Ogden Dunes102/21/202111005102/20/202112005102/22/202109004701/31/2021170042
Michigan City-W. Michigan Blvd102/21/202110005102/20/202113005102/22/202111004802/26/2021090042
LaPorte-E. Lincolnway102/21/202111005202/20/202112004902/22/202110004702/24/2021110042
North Central
South Bend-Shields Dr102/21/202114005002/22/202112004402/20/202112004202/23/2021130039
Potato Creek State Park102/21/202112005302/20/202117005302/22/202109004902/23/2021140047
Granger-Beckley St102/21/202112005102/20/202112004502/22/202108004402/23/2021150040
North East
Fort Wayne-Beacon St102/21/202112005202/22/202108004802/24/202110004502/20/2021120045
Leo HS102/22/202109004602/19/202112004502/24/202110004202/23/2021130042
West Central
Terre Haute-Lafayette Ave102/20/202110004902/21/202112004802/22/202109004302/19/2021110042
West Union102/20/202111005502/21/202111005102/22/202109004802/19/2021100047
East Central
Anderson-Eastside Elem. School202/20/202112005102/24/202112004802/22/202108004802/19/2021110048
Indpls-Washington Park102/20/202112004602/21/202111004502/24/202112004302/22/2021070043
Indpls-Harding St102/20/202111004802/21/202111004602/19/202110004202/24/2021110040
Indpls-Ft. Harrison102/24/202112004402/22/202109004402/19/202110004402/12/2021120041
Noblesville-191st St102/20/202112004802/21/202110004702/24/202113004502/22/2021070045
Indpls - I-70 E102/21/202112004402/20/202112004402/22/202115003602/26/2021100034
Kokomo - E. Vaile Ave.102/20/202111005402/22/202107005102/21/202110005102/24/2021110050
South West
Evansville-Buena Vista Rd102/24/202110004502/23/202109004102/25/202110004002/11/2021110039
St. Philips102/20/202110005002/19/202111004602/18/202113004402/21/2021110043
South East
New Albany102/24/202110004702/19/202111004602/22/202109004302/23/2021100042
Charlestown State Park102/19/202113004802/24/202111004702/20/202112004702/23/2021120045
POC (Parameter Occurrence Code): a code used to correctly separate data from multiple instruments at one site.

Interpreting the AQI

Air Quality Index

Each NAAQS pollutant has a separate AQI scale, with an AQI rating of 100 corresponding to the concentration of the Federal Standard for that pollutant. Additional information about the AQI and how it can be used is available from the EPA's AirNow web site.

Place your mouse pointer over the scale displayed above to view information about the Air Quality Index, and each of the rating levels.

The actual index calculation is different for each parameter measured and is specified by the EPA. The following table shows the various breakpoints used in calculating the AQI.

AQI Breakpoint Definitions
AQI Range 1hr Ozone
in ppm
8hr Ozone
in ppm
0 - 50 Not Defined 0 - 0.054
51 - 100 Not Defined 0.055 - 0.070
101 - 150 0.125 - 0.164 0.071 - 0.085
151 - 200 0.165 - 0.204 0.086 - 0.105
201 - 300 0.205 - 0.404 0.106 - 0.200
301 - 400 0.405 - 0.504 0.201 - 0.2011
401 - 500 0.505 - 0.604 Not Defined
500+ Not Defined Not Defined

PLEASE NOTE: This data has not been verified by the IDEM and may change. This is the most current data, but it is not official until it has been certified by our technical staff. Data is collected from IDEM ambient monitoring sites and may include data collected by other outside agencies. This data is updated hourly. All times shown are in local standard time unless otherwise indicated.