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Four Highest Eight-Hour Ozone Concentrations in 2017
as of April 30

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 2017 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 St104/25/201712005604/09/201711005004/26/201709004904/23/2017100047
Ogden Dunes104/25/201711005704/18/201710005504/24/201711005404/15/2017100053
Michigan City-W. Michigan Blvd104/24/201710006204/09/201710005804/18/201710005704/26/2017090056
Valparaiso104/24/201710006104/25/201711005804/09/201710005804/18/2017100056
Gary-IITRI104/25/201711005904/24/201711005904/18/201710005604/15/2017100056
LaPorte-E. Lincolnway104/24/201709005904/09/201711005704/26/201710005504/18/2017110055
North Central
South Bend-Shields Dr104/26/201711006104/09/201711005304/18/201712005004/15/2017110048
Bristol104/09/201712005604/26/201712005504/24/201711005204/18/2017120052
Potato Creek State Park104/24/201712006004/09/201711006004/26/201711005804/18/2017130058
Granger-Beckley St104/26/201711006004/09/201711006004/24/201710005904/18/2017120056
North East
Fort Wayne-Beacon St104/26/201712005604/18/201712005604/09/201710005604/24/2017120054
Leo HS104/26/201712005804/09/201711005804/15/201711005604/24/2017120055
Roanoke Elem. School104/09/201711005604/18/201711005404/08/201712005404/26/2017100053
West Central
Terre Haute-Lafayette Ave104/24/201711006304/25/201712006004/09/201710006004/14/2017110058
Flora104/09/201710005904/24/201711005704/18/201711005704/26/2017100056
Sandcut104/24/201711006304/09/201710005904/25/201712005804/14/2017110057
West Union104/24/201710006004/09/201710005804/25/201710005604/23/2017100055
East Central
Indpls-E.16th St104/09/201711005904/24/201711005704/18/201710005604/13/2017100056
Emporia104/14/201711005904/09/201711005604/18/201710005504/26/2017110054
Albany104/09/201711005804/26/201711005604/18/201711005604/15/2017100056
Indpls-Washington Park104/09/201711005704/24/201711005604/13/201711005404/18/2017100053
Indpls-Harding St104/24/201712005704/18/201712005504/13/201711005304/09/2017130053
Indpls-Ft. Harrison104/09/201712005904/13/201711005704/24/201711005604/14/2017110056
Monrovia104/09/201711005504/24/201712005404/14/201711005104/13/2017120051
Trafalgar104/09/201711006104/14/201711005904/13/201711005904/24/2017110057
Whitestown104/09/201711005704/25/201711005604/24/201711005504/26/2017110052
Avon104/09/201712005904/13/201712005604/24/201711005504/26/2017110054
Fairland104/14/201712006304/13/201712006004/09/201713005804/24/2017110057
Noblesville-191st St104/09/201712005904/14/201711005604/24/201711005504/18/2017100054
Hope104/14/201710006004/13/201711005904/09/201712005804/10/2017090056
Indpls - I-70 E104/09/201711005504/25/201712005204/24/201713005104/26/2017110050
Helmsburg104/09/201711006204/13/201711006004/14/201711005904/10/2017090059
South West
Boonville104/09/201710006004/13/201710005904/24/201710005504/14/2017100055
Evansville-Buena Vista Rd104/13/201710005804/09/201709005804/14/201710005504/24/2017100054
Lynnville104/09/201710005704/13/201710005504/24/201711005204/14/2017100051
Inglefield104/09/201710006004/13/201710005804/14/201710005704/24/2017100055
St. Philips104/09/201710005804/13/201710005704/24/201711005603/09/2017110055
Leopold104/14/201710005904/13/201711005904/09/201709005804/10/2017080057
Dayville104/13/201711005604/09/201709005603/09/201712005404/24/2017100052
Plummer104/24/201711006204/09/201711006204/13/201711006104/25/2017110057
South East
New Albany104/13/201711006004/14/201711005904/10/201711005904/09/2017120058
Charlestown State Park104/14/201712006704/13/201712006404/10/201711006004/09/2017100057
Brownstown104/09/201711005604/24/201711005504/25/201713005404/13/2017110054
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.