Indiana’s statewide ambient air monitoring network includes different types of monitors that collect pollutant and meteorological data for many purposes: U.S. EPA-approved state or local air monitoring stations (SLAMS) collect criteria pollutant data needed for comparison with the National Ambient Air Quality Standards (NAAQS) but may serve other data purposes as well; special purpose monitors (SPMs) collect data for short-term studies; and other monitors collect data such as air toxics monitoring data and meteorological data.
IDEM uses the data to determine whether Indiana meets the NAAQS. The NAAQS are regulations U.S. EPA sets for six common pollutants that can harm human health and the environment. These common pollutants are known as criteria pollutants, and they include carbon monoxide (CO), lead, nitrogen dioxide (NO2), ozone, particulate matter (PM10 and PM2.5) and sulfur dioxide (S2).
IDEM uses the data to provide current air quality conditions and issue forecasts:
- Indiana’s SmogWatch Air Quality Forecasts for ground-level ozone and PM2.5.
- Air Quality Action Day advisories, when IDEM meteorologists forecast that ozone or PM2.5 could build to unhealthy levels.
- The daily Air Quality Index (AQI), which uses U.S. EPA’s scale to rate Indiana’s air quality for five criteria pollutants and the level of health concern for sensitive individuals. U.S. EPA explains AQI Basics online.
IDEM also uses the data for:
- The development of air quality plans, including state implementation plans (SIPs), that outline how Indiana will control air pollution from emission sources such as industries, small business and commercial sources, and motor vehicles, to protect human health and the environment.
- Air dispersion models for SIPs and air permitting activities. Air dispersion modeling provides mathematical estimates of pollutant concentrations based on inputs, including actual ambient air measurements, reported emissions, and meteorological data.
- Air toxics assessments, to understand how hazardous air pollutants from industrial operations, area sources and motor vehicles are affecting air quality.
- Air risk assessments, to evaluate potential public health threats posed by air toxics in specific neighborhoods and communities.;
- Assessing long-term trends (e.g., reductions or increases of pollutant concentrations over time).
- Special monitoring projects that may be conducted to gain better knowledge about certain pollutants and impacts to the surrounding community. For example, IDEM may conduct special monitoring to guide the placement of a new ambient air monitor or investigate emerging pollutants of concern.
U.S. EPA uses Indiana’s air monitoring data on AirNow, a website that provides air quality information at state, national, and world views using the U.S. AQI. U.S. EPA also uses Indiana’s data for air quality studies and assessments conducted at the federal level.
IDEM maintains the samplers and instruments that collect continuous and noncontinuous air samples for analysis. IDEM manages the monitoring data using its online Data Management and Display System which is available to the public, enabling anyone to access current and historical information about the air we breathe.