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England and Wales
The following data-quality objectives for the required accuracy of assessment methods, of minimum time coverage and of data capture of measurement are laid down to guide quality-assurance programmes.
| Sulphur dioxide, nitrogen dioxide and oxides of nitrogen | Particulate matter and lead | |
|---|---|---|
| Continuous measurement | ||
| Accuracy | 15% | 25% |
| Minimum data capture | 90% | 90% |
| Indicative measurement | ||
| Accuracy | 25% | 50% |
| Minimum data capture | 90% | 90% |
| Minimum time coverage | 14% (One measurement a week at random, evenly distributed over the year, or eight weeks evenly distributed over the year.) | 14% (One measurement a week at random, evenly distributed over the year, or eight weeks evenly distributed over the year.) |
| Modelling | ||
| Accuracy: | ||
| Hourly averages | 50%—60% | |
| Daily averages | 50% | |
| Annual averages | 30% | 50% |
| Objective estimation | ||
| Accuracy: | 75% | 100% |