{
  "url": "https://openlegislation.uk/air-quality-wales-regulations-2000/schedule/paragraph-4",
  "json_url": "https://openlegislation.uk/air-quality-wales-regulations-2000/schedule/paragraph-4.json",
  "legislation": "wsi/2000/1940",
  "legislation_title": "The Air Quality (Wales) Regulations 2000",
  "legislation_url": "https://openlegislation.uk/air-quality-wales-regulations-2000",
  "path": "schedule/paragraph/4",
  "kind": "paragraph",
  "number": "4",
  "heading": null,
  "text": "An hourly mean is a mean calculated every hour. The hourly mean for a particular substance at a particular location for a particular hour is the mean of the levels recorded for that substance at that location:\n(a) in the case of benzene, at a frequency of not less than once during the hour; and\n(b) in the case of carbon monoxide, nitrogen dioxide and sulphur dioxide, at a frequency of not less than once every 10 seconds during the hour.",
  "extent": "E+W",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "F",
      "label": "F1",
      "text": "Words in Sch. Pt. 2 para. 4 substituted (31.12.2002) by The Air Quality (Amendment) (Wales) Regulations 2002 (S.I. 2002/3182), regs. 1(1), 2(3)(c)"
    },
    {
      "type": "I",
      "label": "I1",
      "text": "Sch. Pt. 2 para. 4 in force at 1.8.2000, see reg. 1(1)"
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/wsi/2000/1940/schedule/paragraph/4",
    "retrieved_at": "2026-10-29T00:18:33.450536+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."
}