IDEM Continuous Air Quality Monitoring

Air Quality Index
How clean is the air in your metropolitan area? The U. S. Environmental Protection Agency (EPA) has provided a scale called the Air Quality Index (AQI) for rating air quality. This scale is based on the National Ambient Air Quality Standards (NAAQS) and is described in the Code of Federal Regulations, Part 58, Appendix G. This report is based on the AQI standards.

Interpreting the AQI

Reporting for January 6, 2009 as of 9:18 pm EST
Metropolitan Area or Non-Metropolitan County		Air Quality		Critical Pollutant	Air Quality Index Rating
					Ozone				Carbon Monoxide		Sulfur Dioxide		PM-10 (Std Cond)		PM-2.5 (Lcl Cond)
					1-Hour		8-Hour		8-Hour		24-Hour †		24-Hour †		24-Hour †
					AQI	ppb	AQI	ppb	AQI	ppm	AQI	ppb	AQI	ug/m3	AQI	ug/m3
North West -- Region 1
	Gary ¹		Good	PM-10		§		§			3	2	8	8.8
	Michigan City ¹	††				§		§
North Central -- Region 2
	Elkhart-Goshen ¹	††				§		§
	South Bend ¹		Moderate	PM-2.5		§		§							54	16.8
North East -- Region 3
	Fort Wayne ¹		Good	Carbon Monoxide		§		§	13	1.2
West Central -- Region 4
	Carroll County, IN ¹	††				§		§
	Clark County, IL ¹	††				§		§
	Lafayette		Good	PM-2.5											43	13.3
	Terre Haute ¹		Good	Sulfur Dioxide		§		§			1	1
East Central -- Region 5
	Indianapolis ¹		Good	Carbon Monoxide		§		§	6	0.5	0	0
	Muncie ¹	††				§		§
South West -- Region 6
	Evansville-Henderson ¹		Good	Sulfur Dioxide		§		§			3	2
	Leopold ¹	††				§		§
South East -- Region 7
	Louisville ¹		Good	Sulfur Dioxide		§		§			1	1
PM-10 is measured at standard pressure and temperature conditions.
PM-2.5 is measured at local pressure and temperature conditions.
† This is an average since midnight for the current day and does not represent an entire day's worth of data.
†† No AQI has been calculated for this metropolitan area. This can happen early in the morning before enough valid ozone or carbon monoxide hourly samples have been collected to create an eight-hour average and should clear up once enough samples are collected. If there are no measurements for any parameter, this indicates a data collection problem. Once this problem is resolved, the data will be filled in and a AQI will be calculated (if possible).
¹ Not all monitors are reporting for this metropolitan area.
§ No data of this type was collected on January 6, 2009 for this metropolitan area, or there were not enough valid hourly samples collected on this date to meet data completeness requirements of a minimum of 18 valid hourly samples in a day.

PLEASE NOTE: Data in this table is collected from IDEM air monitoring sites, local agencies, and private monitoring networks. Site specific information is available for each metropolitan area by clicking on the metropolitan area name. This data has not been verified by the IDEM or the responsible entity and may change. While this is the most current data, it is not official until it has been certified by the appropriate technical staff. This table is updated hourly. Click here for information about all the monitoring sites.

The table above lists the current peak concentration for the critical pollutant, the corresponding Air Quality Index (AQI) category, and the AQI ratings for each of the NAAQS pollutants that are measured real-time. The critical pollutant is the pollutant with the highest AQI rating measured in the area. The table is updated each hour and covers the period from midnight through the indicated ending time for today's data or from midnight to midnight on other days. Listings are provided for each metropolitan area where pollutant levels are monitored by the TCEQ. Critical pollutant concentrations for ozone and sulfur dioxide are shown in parts per billion (ppb), carbon monoxide measurements are shown in parts per million (ppm), and particulate matter (PM-10 and PM-2.5) concentrations are shown in micrograms per cubic meter (ug/m3).

Interpreting the AQI

Each NAAQS pollutant has a separate AQI scale, with a 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.

The AQI scale is divided into the following categories:

Air Quality
Good	Moderate	Unhealthy (for sensitive groups)	Unhealthy	Very Unhealthy	Hazardous

The AQI for ozone is based on the either the peak eight-hour running average since midnight OR the peak one-hour measurement since midnight. The AQI's for sulfur dioxide, PM-10, and PM-2.5 are based on a 24-hour average sampled from midnight to midnight, and the AQI for carbon monoxide is based on the peak eight-hour running average since midnight. On most days the critical pollutant is ozone. Ozone one-hour average concentrations of 125 ppb or higher exceed the old NAAQS ( AQI rating of 106 or higher). The new NAAQS for ozone is based on eight-hour averages and applies in all areas that are classified as attainment for the old one-hour NAAQS. An eight-hour average of 85 ppb exceeds the new NAAQS for ozone. All areas currently classified as nonattainment for the old one-hour standard will still be required to achieve attainment of the one-hour standard.