- How do I re-activate a monitor?
- Does AQS automatically change data less than the MDL to 1/2 MDL?
- How does the EPA locational data policy affect AQS?
- How do I find out what the codes used in AQS mean?
- What data counts when determining the percent completeness?
To reactivate a monitor, add a new sampling period with the start date valued for the appropriate date. If the monitor type records are all closed, a new monitor type record will need to be created.
The raw data file contains two raw data fields: reported raw data value and value in standard units. The raw data value as reported is stored in the first field. The data value in standard units is computed from the reported value, a conversion factor using the gas laws, and the minimum detection value. Any reported value below the minimum detection value is replaced with 1/2 the minimum detection value.
This policy required the addition of three additional meta data fields. These new fields are required to add a new site to the database beginning with version 2.1. These fields must also be populated whenever an existing site is updated with Maintain. These data fields provide additional meta data for LDP Vertical Measure (formerly elevation above mean sea level) and include: Vertical Method and Vertical Datum with reference tables and drop downs of valid values and Vertical Accuracy Value in meters. This modification also revises the transaction format for site transactions.
The new transaction formats are available at: http://www.epa.gov/ttn/airs/airsaqs/manuals/aqstrans_format.pdf.
The Data Dictionary and Data Coding Manuals provide a description of the codes used in AQS. These manuals are found on the "Manuals and Guides" page. In addition, here are links to files for some of the most common ones are on the "Selected AQS Codes Descriptions" page.
The sample period begin and end dates determine the amount of data expected when computing data completeness. This would only apply for the first or last quarter or year that the monitor is operating.
The second part of the equation is the number of samples reported. Null data codes are not valid sample values so are not counted as reported values. For duration = 1, the calculation is assuming 24 values per day. For 24-hr sampling, for other than PM data, the calculation is based on an every 6 day sampling schedule.