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AQS Format
Contents of Air Quality System pipe ("|") delimited format files. (This format was developed as the input and output format of the AQS system.)
Note
This section makes many references to AQS codes. Many EPA systems
transmit and store codes instead of long text descriptions to save space.
To see the meanings of the codes, visit the AQS Code
Description web page.
Unlike the other formats, files in this format have their fields
separated by the pipe ("|") character. The only reason it is provided to
users is that many historical AQS data sets are available in this format
and users have written code to ingest it. We provide it to prevent those
users from having to adjust their own work.
| Field Position | Field Name | Description |
|---|---|---|
| 1 | Transaction Type | Two-character identifier of the contents of the remainder of the fields in the row. For QAD, the currently allowed value is "RD" for Raw Data. |
| 2 | Action Code | Action code for data ingesting. Not relevant to data obtained from QAD. Always "I" (insert). |
| 3 | State Code | The FIPS code of the state in which the monitor resides. |
| 4 | County Code | The FIPS code of the county in which the monitor resides. |
| 5 | Site ID | A unique number within the county identifying the site. |
| 6 | Parameter | The AQS code corresponding to the parameter measured by the monitor. |
| 7 | POC | This is the “Parameter Occurrence Code” used to distinguish different instruments that measure the same parameter at the same site. |
| 8 | Sample Duration | A code representing the length of time that air passes through the monitoring device before it is analyzed (measured). So, it represents an averaging period in the atmosphere (for example, a 24-hour sample duration draws ambient air over a collection filter for 24 straight hours). For continuous monitors, it can represent an averaging time of many samples (for example, a 1-hour value may be the average of four one-minute samples collected during each quarter of the hour). |
| 9 | Unit | Three-digit AQS code representing the units of measurement of the specified parameter. |
| 10 | Method | Three-digit AQS code that identifies the method used to perform the measurement. |
| 11 | Date | The calendar date of the sample in Local Standard Time at the monitor. |
| 12 | Start Time | The time of day that sampling began on a 24-hour clock in Local Standard Time. |
| 13 | Sample Value | The measured sample value in the standard units of measure for the parameter. |
| 14 | Null Data Code | If no sample value is available, a code indicating the reason. |
| 15 | Sampling Frequency | A code representing how often the monitor takes a sample. For hourly data (Duration = 1 hour), this field is null and means the frequency is continuous (that is, also 1 hour). |
| 16 | Monitor Protocol (MP) ID | A code representing the protocol (duration, unit, method and method detection limit) of the sample. Not relevant to data obtained from QAD. Always empty. |
| 17 - 26 | Qualifier 1 - 10 | Codes representing any qualifiers on the data. Sample values may have up to 10 qualifiers that indicate why they are out of the ordinary. Types of qualifiers are: exceptional event, natural events, and quality assurance. |
| 27 | Alternate Method Detectable Limit | The minimum sample concentration detectable for the monitor and method. NOTE: IF SAMPLES ARE REPORTED BELOW THIS LEVEL, THEY MAY BE REPLACED WITH ½ THIS LIMIT. (Note, for QAD, this may be the alternate or federal limit, whichever is relevant to the sample.) |
| 28 | Uncertainty | The total uncertainty associated with a reported measurement as indicated by the reporting agency. |