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ToxWatch Monitoring Data Study 2012-2021

ToxWatch screens data collected through the ambient air quality monitoring program conducted by the Office of Air Quality (OAQ) within the Indiana Department of Environmental Management (IDEM). The program actively monitors air toxic concentrations at various monitoring sites within the state of Indiana. At any given time, there are approximately 10 active monitoring sites within the state. The study presented here pulled air toxic concentration readings that were collected over a ten-year period from 2012-2021. The monitoring sites selected were those which were active by 2016. Based on these criteria, the following locations and monitoring years were included:

CountyCity Monitor Site Name Monitoring Years
Lake East Chicago East Chicago - Marina 2012-2021
Gary Gary IITRI 2012-2021
Hammond Hammond - 141st St. 2012-2021
Whiting Whiting - Center St. 2016-2021
Porter Ogden Dunes Ogden Dunes 2012-2021
Vigo Terre Haute Terre Haute - Fort Harrison Rd. 2014-2021
Marion Indianapolis Indianapolis - Washington Park 2012-2021
Indianapolis I-70 E 2016-2021
Vanderburgh Evansville University of Evansville 2012-2021
Clark Clarksville Clarksville 2012-2021

The U.S. Environmental Protection Agency’s (EPA) Air Quality System (AQS) contains raw data from monitoring sites that are collected, analyzed, and submitted by each state into the AQS database.  Three types of reports from AQS were utilized for this study that include the QUICKLOOK ALL PARAMETERS – AMP 450NC, DAILY SUMMARY REPORT – AMP435, and the DATA COMPLETENESS REPORT – AMP430.  From the AQS data, a detection rate was determined. The detection rate is defined as the percentage of valid samples taken at each monitor that had a quantifiable concentration of the pollutant. The quantifiable concentration is equal to the Federal Method of Detection Level (FMDL) for the instrument that was used in collecting pollutant samples.  For each pollutant where the average detection rate was 50% or higher, an analysis of concentration trends was performed. If the detection rate was below 50% for a pollutant this analysis was not performed due to the limited amount of quantifiable data.  Individual monitors were removed from the concentration trend charts that averaged detection rates less than 50%.  Whiting–Center St. was not included due to a change in exact monitor location mid-study.  These analyses that comprise the trend charts consisted of averaging annual and/or daily arithmetic means from the QUICKLOOK ALL PARAMETERS - AMP 450NC and DAILY SUMMARY REPORT – AMP435.

Trend charts include reference concentrations (RfC) that are an estimate of continuous inhalation exposure that is likely to be without appreciable health effects during a lifetime (chronic).  These are chronic non-cancer thresholds, below which, health effects are not expected to be observed for each pollutant.  Reference concentrations (RfC) included on these trend charts are the same values as used for air permit modeling available at IDEM: Air Quality: Modeling under Hazardous Air Pollutants (HAPS) Table [XLSX], “Chronic” tab in the worksheet.  For more information on cancer-risk estimates please refer to the previous IDEM: Air Toxics: ToxWatch Monitoring Data Study 2006-2015.

10-Year Trend Charts

Previous full study reports with emissions for each pollutant are provided in the previous IDEM: Air Toxics: ToxWatch Monitoring Data Study 2006-2015. The Monitoring page provides additional information about the IDEM Air Monitoring Program. The Air Toxics Monitor Siting Process page provides information about current air monitoring sites.

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