Particulate matter days

This indicator shows the annual number of days with maximum 24-hour average PM 2.5 concentration over the National Ambient Air Quality Standard. Air Quality Standard monitoring data were used for counties and days with monitors and hierarchical Bayesian data were used for any county or day without monitors. The spatial resolution of the HB grid cell used is 36 Km. The grid cell values were transferred to counties based on a population weighted approach. The indicators are available for counties/states in the conterminous US (Lower 48 + Washington DC). HB modeled data are not available for AK and HI. The state and national values are an average of county values weighted by population size.

  • Adams
  • Measurement Period: 2005
Particulate matter days
RANGE: 0<4

Understanding the color Range

Each Health Indicator includes five-color range indexes. The color range index compares all counties in the state that have the same indicator in the same timeframe. It then calculates where the selected county falls in that range and displays the color that best reflects how the county is doing in comparison to the other counties in the filtered group. The range displays the highest and lowest county values within the state that have the same indicator for the same measurement period.

Current county values will be compared to State and National values if they are available.

Green and red arrows indicate that the county value is better or worse than the state or national value. The arrows will change directions and colors based on which end of the range is positive.
This icon simply means that the county value is equal to the state or national value.
Some indicators display blue, which means the data is not meant for health-status comparison, but is intended simply to provide information.
If history data is available the trend icon will point up or down based on its relationship to the last county value.
Dimensions 2005
Dimension Low Value High Number of Counties Compared
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Air Quality System
The Air Quality System (AQS), formerly the Aerometric Information Retrieval System (AIRS), is the Environmental Protection Agency's (EPA) repository of ambient air quality data. AQS stores data from over 10,000 monitors, 5,000 of which are currently active. The system contains ambient air pollution data collected by EPA, state, local, and tribal air pollution control agencies.  AQS also contains meteorological data, descriptive information about each monitoring station (including its geographic location and its operator), and data quality assurance/quality control information.  The Office of Air Quality Planning and Standards (OAQPS) and other AQS users rely upon the system data to assess air quality, assist in Attainment/Non-Attainment designations, evaluate State Implementation Plans for Non-Attainment Areas, perform modeling for permit review analysis, and other air quality management functions.  AQS information is also used to prepare reports for Congress as mandated by the Clean Air Act.


EPA regulations require state environmental agencies to report air monitoring data at least quarterly. Data for one calendar quarter are due to EPA by the end of the following quarter.