![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
About the Monitor Locator Map - Hazardous Air Pollutants
What does the map tell me?
A Monitor Locator Map shows the locations of air monitoring sites that measure ambient concentrations of hazardous air pollutants that you choose. The map has a symbol at the latitude-longitude coordinates of each air monitoring site. The map legend tells how many monitoring sites are in the map.
What does the map look like?
This image shows a Monitor Locator map for selected counties in Southern California. Each shaded county has at least one monitoring site for hazardous air pollutants. Monitor locations are indicated by markers on the map, and the legend tells how many there are. This map also shows optional features: Class I areas (outlined in light green) and interstate, federal, and state highways.
How can I customize the map?
To generate a Monitor Locator map, choose at least one pollutant. You may also choose optional criteria to refine data selection and add geographic features to the map. The selection criteria are described below.
- Geographic Area
- The name of the geographic area previously selected is displayed here.
You can click on "change" to choose a different area.
- Pollutant (required)
- Selects monitoring sites based on the hazardous
air pollutants they measure and report to EPA. Choose at least
one pollutant. (You may choose up to 20.)
- Year Monitor Active (optional)
- Selects monitors that reported data in a particular year. You may select
up to eleven years. If you do not select a year, the map includes monitors
that reported data in the latest year for which data are available.
- Monitor Type (optional)
- Selects air monitors based on the purpose for which they were established
or the monitoring network to which they belong. You may select multiple
monitor types. If you do not select this option, monitor type plays no
role in determining which monitoring sites to include in a map.
- Circle At Monitor Location (optional)
- Adds circles on the map centered at the location of each monitoring
site. You set circle size by selecting a radius value, in miles. A circle
radius up to 50 miles is valid. The circles can make it easier to see
monitor locations on a map, and they provide a sense of scale, since
the circle radius is known, and is displayed in the map legend. If you
do not enter a radius value, the map does not include circles at monitor
locations.
- Geographic Features (optional)
- Enhances a map with features such as city locations, highways, and
national park outlines. Without this option selected, the map includes
standard features: markers indicating monitor locations, and outlines
of geographic areas.