{
  "url": "https://openlegislation.uk/air-quality-ozone-wales-regulations-2003/schedule-5/part-I",
  "json_url": "https://openlegislation.uk/air-quality-ozone-wales-regulations-2003/schedule-5/part-I.json",
  "legislation": "wsi/2003/1848",
  "legislation_title": "The Air Quality (Ozone) (Wales) Regulations 2003",
  "legislation_url": "https://openlegislation.uk/air-quality-ozone-wales-regulations-2003",
  "path": "schedule/5/part/I",
  "kind": "part",
  "number": "I",
  "heading": "Data quality objectives",
  "text": "The following data quality objectives for allowed uncertainty of assessment methods and of minimum time coverage and of data capture of measurement are provided to guide quality-assurance programmes:\nFor ozone, NO and NO2\nThe uncertainty (on a 95% confidence interval) of the measurement methods must be evaluated in accordance with the principles laid down in the “Guide to the Expression of Uncertainty of Measurements” (ISO 1993) or the methodology in ISO 5725-1 “Accuracy (trueness and precision) of measurement methods and results” (ISO 1994) or equivalent. The percentages for uncertainty in the table are given for individual measurements, averaged over the period for calculating target values and long-term objectives, for a 95% confidence interval. The uncertainty for continuous fixed measurements should be interpreted as being applicable in the region of the concentration used for the appropriate threshold.\nThe uncertainty for modelling and objective estimation means the maximum deviation of the measured and calculated concentration levels, over the period for calculating the appropriate threshold, without taking into account the timing of events.\n“Time coverage” means the percentage of time considered for settling the threshold value during which the pollutant is measured.\n“Data capture” means the ratio of the time for which the instrument produces valid data, to the time for which the statistical parameter or aggregated value is to be calculated.\nThe requirements for minimum data capture and time coverage do not include losses of data due to the regular calibration or normal maintenance of the instrumentation.\nContinuous fixed measurement\nUncertainty of individual measurements\n15%\nMinimum data capture\n90% during summer 75% during winter\nIndicative measurement\nUncertainty of individual measurements\n30%\nMinimum data capture\n90%\nMinimum time coverage\n>10% during summer\nModelling\nUncertainty\n1 hour averages (daytime)\n50%\n8 hours daily maximum\n50%\nObjective estimation\nUncertainty\n75%",
  "extent": null,
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "Copies of these International Standards Organisation publications can be purchased from the British Standards Institution “BSI” sales department either by telephone on 020-8996-9001 or by post from the BSI, Standards House, 389 Chiswick High Road, London, W4 4AL"
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/wsi/2003/1848/schedule/5/part/I",
    "retrieved_at": "2026-10-29T00:10:44.777755+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}