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What IDEM Monitors

IDEM operates a statewide network to monitor pollutants and meteorological parameters according to requirements in federal regulations:

  • IDEM monitors for six common air pollutants that are regulated under U.S. EPA’s National Ambient Air Quality Standards (NAAQS). These pollutants are known as criteria pollutants, and they include carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), particulate matter [PM10 and PM2.5] and sulfur dioxide (SO2). IDEM's Data Management and Display System provides online access to near real-time air quality data from the statewide monitoring network.
  • Following is information concerning how the common (criteria) pollutants are measured, as well as data collected on non-criteria parameters:
    • State and Local Air Monitoring Stations (SLAMS) - The federal Clean Air Act requires states to establish a network of SLAMs for the criteria pollutants. States provide U.S. EPA with summary of monitoring results on an annual basis.
    • PM2.5 Speciation - PM2.5 is a mixture of different types of microscopic solid particles and liquid droplets, primarily from industrial processes and fuel combustion. PM2.5 emissions come directly from sources; however, the pollutant also can form in the atmosphere when other directly emitted pollutants combine. Speciation data refers to data on the chemical makeup (sulfates, nitrates, organic and elemental carbon, ammonium, metals, and certain ions) of PM2.5. IDEM collects PM2.5 speciation data at certain monitoring sites as part of a national PM2.5 Chemical Speciation Network (CSN), established by U.S. EPA under the PM2.5 NAAQS (the CSN consists of Speciation Trends Network (STN) sites and supplemental speciation sites). U.S. EPA uses speciation data to develop seasonal and annual chemical characterizations of ambient particulates across the nation; perform source attribution analyses; evaluate emission inventories and air quality models; and support health-related research studies and regional haze assessments. Black carbon data aids in U.S. EPA research on sources, measurement, health effects, and air quality impacts of the pollutant.
    • NCore Monitoring - IDEM operates a multi-pollutant monitoring site in Indianapolis to fulfill requirements established by U.S. EPA for its National Core (NCore) Multi-pollutant Network. U.S. EPA’s NCore network began operations on January 1, 2011, and integrates several advanced measurement systems for trace levels of particles, pollutant gases and meteorology to support numerous monitoring objectives . Measured parameters include continuous and intermittent PM2.5, PM2.5 speciation, PM10-2.5 particle mass, CO, O3, SO2, nitrogen monoxide (NO), total reactive nitrogen oxides (NOy), and meteorological conditions.
    • Photochemical Assessment Monitoring (Ozone Precursors) - Of the six criteria pollutants, ozone is the most prevalent photochemical oxidant and an important contributor to smog. Ozone is not directly emitted into the air by any single source. Instead, it forms in the atmosphere from a chemical reaction between other directly emitted pollutants, primarily nitrogen oxides (NOx) and volatile organic compounds (VOCs), which are known as precursor pollutants. Thousands of sources of ozone precursors are located across the country. U.S. EPA uses photochemical assessment monitoring stations (PAMS) data to study the chemicals, reactions, and conditions that contribute to ozone formation. IDEM monitors that are part of U.S. EPA’s PAMS program measure hourly averaged speciated VOCs, mixing height, O3, true NO2, NO, NOy, meteorology and 8-hour carbonyl sampling.
    • Near-Road NO2 Monitoring - U.S. EPA has established requirements for near-road NO2 monitoring sites in larger urban areas where peak hourly pollutant concentrations are expected. U.S. EPA uses near-road monitoring data to assess exposures for those who live, work, play, go to school, or commute within the near-roadway environment. States determine their near-road monitoring requirements based on factors such as population and traffic data. IDEM operates a near-road monitoring site along Interstate 70 in Indianapolis, which collects data on NO2, CO, O3, meteorological conditions, black carbon, air toxics, PM2.5, and ultrafine particle count.
    • Toxic Air Pollutants (VOCs Including Benzene, Metals, and Carbonyls) - Toxic air pollutants are pollutants that are known or suspected to cause cancer and other serious non-cancer health effects, as well as adverse environmental conditions. Many types of sources release toxic compounds, including mobile sources (vehicles), stationary industrial sources, small area sources, indoor sources (cleaning materials, etc.), and environmental sources (wildfires, etc.). U.S. EPA works with state, local, and tribal governments to reduce air toxics releases to the environment, improve understanding of urban air toxics, and reduce risks. U.S. EPA has issued rules covering over 80 categories of major industrial sources, such as chemical plants, oil refineries, aerospace manufacturers, and steel mills, as well as categories of smaller sources, such as dry cleaners, commercial sterilizers, secondary lead smelters, and chromium electroplating facilities. IDEM locates air toxics monitoring sites in urban areas with large populations and multiple sources that are most likely to be impacted by emissions. Data is collected on more than 80 pollutants, including semi-VOCs, VOCs, metals and carbonyls, enabling U.S. EPA and IDEM to identify trends and patterns; use mathematical models to predict problems; and assess public health risks based on measured concentrations and models.
    • Ammonia Monitoring Network (AMoN): The AMoN is the only network providing a consistent, long-term record of ammonia gas concentrations across the United States.
    • RadNet monitoring network: RadNet has 140 radiation air monitors in 50 states and runs 24 hours a day, 7 days a week collecting near-real-time measurements of gamma radiation. Over time, RadNet sample testing and monitoring results reveal the normal background levels of environmental radiation.
    • Special Purpose Monitor (SPM): IDEM uses SPMs to fulfill very specific or short-term monitoring goals.
    • Carbon Dioxide - IDEM monitors carbon dioxide (CO2), the primary greenhouse gas emitted through human activities such as the combustion of fossil fuels (e.g., coal, natural gas, oil) for energy and transportation. CO2 is naturally present in the atmosphere as part of the earth's carbon cycle, which is the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals. CO2 emissions come from a variety of natural sources. Human activities can influence the carbon cycle by adding more CO2 to the atmosphere and influencing the ability of natural sinks, like forests, to remove CO2 from the atmosphere.
    • Meteorological Monitoring - IDEM collects data on wind speed and direction, temperature, humidity, dew point temperature, precipitation, barometric pressure, and ultraviolet and solar radiation in all areas of the state where pollutants are monitored. IDEM measures and analyzes meteorological conditions because the fate of air pollutants is influenced by the movement and characteristics of the air mass into which they are emitted. If the air is calm and pollutants cannot disperse, then the concentration of the pollutants will build up. If a strong and turbulent wind is blowing, pollutants will rapidly disperse into the atmosphere resulting in lower concentrations near the pollution source. IDEM uses meteorological data to issue SmogWatch air quality forecasts and Air Quality Action Day advisories for high pollutant concentration days, and simulate and predict air quality using computer models.
    • Clean Air Status and Trends Network (CASTNET): Part of a national monitoring network established to assess trends in pollutant concentrations, atmospheric deposition, and ecological effects due to changes in air pollutant emissions. U.S. EPA manages and operates CASTNET.

What IDEM Does Not Monitor

IDEM does not monitor indoor air quality or manage complaints about mold, formaldehyde, radon, lead-based paint removal, or other indoor air quality issues. U.S. EPA’s Indoor Environmental Division and the Indiana State Department of Health’s Indoor Air Quality program provide information and assistance on these issues. Local health departments (listed on the ISDH website) may also manage indoor air quality issues. IDEM’s Office of Land Quality provides guidance on vapor intrusion, a process in which chemical vapors from contaminated soil or groundwater affect the indoor air quality in a building.

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