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Background Data

The Department periodically analyzes the monitored concentrations across the state to determine the background value concentrations that should be added to dispersion modeling results for comparison to the National Ambient Air Quality Standards (NAAQS). 

Pollutant

Area

Averaging Period

Background Concentration Value
(µg/m3)

NO2

Urban*

1-hour
Annual

75
15

Rural*

1-hour
Annual

34
5

SO2

Statewide

1-hour
3-hour
24-hour
Annual

32
27
9
1

PM2.5

West*

24-hour
Annual

24
9.7

East*

24-hour
Annual

29
10.9

PM10

Statewide

24-hour

53

CO

Statewide

1-hour
8-hour

1,600
1,000

Pb

Statewide

Rolling 3-month average

0

* Refer to map below for definition of PM2.5 background areas.
Depiction of PM2.5 background areas

This data is intended for use in non-PSD 24-hour PM2.5 modeling analyses conducted using the 2005-2009 meteorological datasets maintained by the Department. The data is formatted for use in the AERMOD dispersion model and is specific to certain areas of the state. Refer to the map shown below and choose the data that matches the location being modeled.

Depiction of PM2.5 baseline area pairing with the 2005-2009 meteorological data
Meteorological Station Background Data
KALO (Waterloo)

West

 

East

KAMW (Ames)

West

 

East

KBRL (Burlington)

 

 

East

KCID (Cedar Rapids)

 

 

East

KDBQ (Dubuque)

 

 

East

KDSM (Des Moines)

West

 

East

KDVN (Davenport)

 

 

East

KEST (Estherville)

West

 

 

KFSD (Sioux Falls)

West

 

 

KIOW (Iowa City)

 

 

East

KLSE (La Crosse)

 

 

East

KLWD (Lamoni)

West

 

 

KMCW (Mason City)

West

 

East

KMIW (Marshalltown)

 

 

East

KMLI (Moline)

 

 

East

KOMA (Omaha)

West

 

 

KOTM (Ottumwa)

West

 

East

KSPW (Spencer)

West

 

 

KSUX (Sioux City)

West

 

 


This data is intended for use in 1-hour NO2 modeling analyses when the non-regulatory default Tier 3 Ozone Limiting Method (OLM) or Plume Volume Molar Ration Method (PVMRM) is utilized in the AERMOD dispersion model. OLM and PVMRM are screening methods used to convert NO to NO2. The background ozone concentration is one of the key inputs for use of OLM and PVMRM. The Department has generated a background ozone concentration file for use anywhere in the state for the time period coinciding with the 2005-2009 meteorological dataset. The file provided below is a combination of the ozone monitor data collected from 12 sites across the state. Due to the non-regulatory status of OLM and PVMRM prior approval from DNR is required when either will be used. This ozone data is pre-approved for all such requests that will utilize the Department's 2005-2009 meteorological data.


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