| Measurements from analysers have to go through a number of checks before they are considered 'ratified'. The first stage of ratification occurs automatically as data are downloaded from the analysers. Data are checked against a series of protocols and then scaled using results from manual calibrations. Measurements appearing on the hourly bulletin ('current air quality') have undergone automatic checks only. |
| The second stage occurs each day as air quality analysts manually check the data, confirm any automatic checks and flag up any faults that require attention. Measurements appearing on the daily bulletin and the seven and 30 day graphs will have undergone this second stage. |
| The third and fourth ratification stages occur in the coming months as more information becomes available. Data can be viewed over longer time periods and results from fortnightly manual calibrations, equipment services and equipment audits can be considered. Measurements cannot be considered 'final' until all stages of the ratification process are complete. The time lag is usually between six months and a year. Up until this date, measurements may change without warning. |
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