The following is a summary of IMPROVE data flagging procedures
conducted by NPS/CIRA. Detailed information are available in the provided
links.
AEROSOL
| Native Flag | Description | VIEWS Status Flag | Status Flag Description |
| AA | ORGANIC ARTIFACT CORRECTED | V5 | Valid value but qualified because of possible contamination |
| AP | POSSIBLE ORGANIC ARTIFACT | V5 | Valid value but qualified because of possible contamination |
| BI | Incorrect installation of sample cartridge during weekly change | M2 | Missing value because invalidated by data originator |
| CG | Clogging Filter, Flow rate less than 18 L/min for more than 1 hour. This affects the cut point of the particle but the concentrations are correct. | V2 | Valid estimated value |
| CL | Clogged Filter, Flow rate less than 15 L/min for more than 1 hour. | M3 | Missing value due to clogged filter |
| DE | Derived or calculated value | V0 | Valid value |
| EP | Equipment Problem | M1 | Missing value because no value is available |
| LF | Low/high flow rate. The average flow rate results in a cyclone cut point outside of the 2-3 micro-m range. This corresponds to flow rates < 21.3 L/min or > 24.3 L/min. | V5 | Valid value but qualified because of possible contamination |
| MV | Missing module level value. | M1 | Missing value because no value is available |
| NA | Not Applicable. This is used for missing modules with non-protocol samplers with less than four modules. | M1 | Missing value because no value is available |
| NM | NORMAL | V0 | Valid value |
| NR | Not Reprocessed, Carbon data between 2000 – 2004 which were not Reprocessed to account for negative OP that had originally been reported as zero. | V0 | Valid value |
| NS | Operator did not install the samples or installed them too late to acquire a valid time. All filters involved. | M1 | Missing value because no value is available |
| OL | Off Line. In some cases, this is used when the sampler is inoperable due to hurricane or fire. For year 2000, this is used for the period after the Version 1 sampler is removed and before the Version 2 samples begins operation. | M1 | Missing value because no value is available |
| PO | Power Outage. All filters involved. | M1 | Missing value because no value is available |
| QA | QA problem suspected, value held back for further investigation | I1 | Invalid value - known reason |
| QD | QUESTIONABLE DATA | V4 | Valid value despite failing to meet some QC or statistical criteria |
| RF | High flow rate. The flow rate is greater than 27 L/min for more than 1 hour. This affects the cut point of the particle but the concentrations are correct. | V5 | Valid value but qualified because of possible contamination |
| SA | Used to indicate some sort of 'Sampling Anomaly', though the exact definition has yet to be satisfactorily defined. | V6 | Valid value but qualified due to non-standard sampling conditions |
| SP | An artifact filter was swapped with a sample filter. | V0 | Valid value |
| SW | Suspected filter swap. | V0 | Valid value |
| UN | The concentrations failed the data validation for unknown reasons. | M2 | Missing value because invalidated by data originator |
| XX | The filter is damaged. | M2 | Missing value because invalidated by data originator |