Air toxics, also known as hazardous air pollutants, are those pollutants that are known or suspected to cause cancer and other serious health effects, or adverse environmental conditions. Although there are natural sources of air toxics such as wildfires, primary emission sources include mobile sources such as motor vehicles; stationary industrial sources; small area sources such as auto refinishing shops and drycleaners; and indoor sources such as chemicals used for cleaning.
IDEM operates a network of air toxics monitoring sites to collect and analyze air samples for toxic compounds released by these various sources. The Air Toxics Program utilizes IDEM’s air toxics monitoring data to glean information about how air toxics may be affecting air quality in Indiana’s local neighborhoods and communities. IDEM’s projects, referred to as ToxWatch, generally involve the statistical analysis of average concentrations of compounds developed over a given period of time and a comparison of these numbers to information about the toxicity of compounds and established screening levels.
- Air Toxics Quarterly Screening:
- IDEM performs a quarterly routine screening to check for unusually high readings at Indiana’s air toxics monitors to see if any immediate action is necessary to protect human health and the environment. The screening involves comparing the concentrations recorded for three months against a set of screening levels calculated from the most recent 10-year ToxWatch Data Analysis. Although IDEM does compare the readings to health protective levels, the primary screening levels are derived from ten years of historical concentrations of each pollutant at each monitoring location to find outliers (levels that are out of the mainstream). Based on the most recent 10-year study, IDEM screens the hazardous air pollutants (HAPS) that have higher detection rates above the minimum detection level (MDL) for the monitoring device, and lower health benchmarks. These pollutants are compared to average concentration ranges calculated from the 10-year study. If concentrations consistently measure above the high range value in a visual analysis, further assessment will be applied to determine and track the variance. IDEM has been performing regular screenings Air Toxics data since 2008 and has yet to encounter an event that required immediate action.
- ToxWatch Data Analysis:
- The ToxWatch Data Analysis Report is the Air Toxics Program’s periodic analysis of air toxics data over a multi-year timeframe. In 2022, IDEM released the third analysis containing a decade’s worth of air toxics monitoring results from 2012 to 2021. This report looked at trends in the data and compared concentrations to health protective data. This report and previous reports are also available on the Air Toxics Program: Studies web page.
IDEM also screens for potential problems from air toxics utilizing air models, which are mathematical simulations of air quality that scientists generate using approved computer programs. Where monitoring or modeling data screenings indicate potential problems in a neighborhood or community, the Air Toxics Program conducts air risk assessments to further investigate air toxics concentrations, potential emission sources, how the public may be exposed, the toxicity of the chemicals of concern, what if any increased health risks may exist, and what if any emission reductions may be needed to protect public health and the environment.