{
  "url": "https://openlegislation.uk/air-quality-limit-values-wales-regulations-2001/schedule-2/part-I",
  "json_url": "https://openlegislation.uk/air-quality-limit-values-wales-regulations-2001/schedule-2/part-I.json",
  "legislation": "wsi/2001/2683",
  "legislation_title": "The Air Quality Limit Values (Wales) Regulations 2001",
  "legislation_url": "https://openlegislation.uk/air-quality-limit-values-wales-regulations-2001",
  "path": "schedule/2/part/I",
  "kind": "part",
  "number": "I",
  "heading": "Upper and lower assessment thresholds",
  "text": "The following upper and lower assessment thresholds will apply:\n(a) SULPHUR DIOXIDE\nHealth protection\nEcosystem protection\nUpper assessment threshold\n60 % of 24-hour limit value (75 μg/m3 , not to be exceeded more than 3 times in any calendar year)\n60 % of winter limit value (12 μg/m3 )\nLower assessment threshold\n40 % of 24-hour limit value (50 μg/m3 , not to be exceeded more than 3 times in any calendar year)\n40 % of winter limit value (8 μg/m3)\n(b) NITROGEN DIOXIDE AND OXIDES OF NITROGEN\nHourly limit value for the protection of human health(NO2)\nAnnual limit value for the protection of human health(NO2)\nAnnual limit value for the protection of vegetation(NOx)\nUpper assessment threshold\n70 % of limit value (140 μg/m3 , not to be exceeded more than 18 times in any calendar year)\n80 % of limit value (32 μg/m3 )\n80 % of limit value (24 μg/m3 )\nLower assessment Threshold\n50 % of limit value (100 μg/m3 , not to be exceeded more than 18 times in any calendar year)\n65 % of limit value (26 μg/m3 )\n65 % of limit value (19.5 μg/m3 )\n(c) PARTICULATE MATTER\n24-hour average\nAnnual average\nUpper assessment threshold\n60 % of limit (30 μg/m3 , not to be exceeded more than seven times in any calendar year)\n70 % of limit value (14 μg/m3 )\nLower assessment threshold\n40 % of 2 limit value (20 μg/m3 , not to be exceeded more than seven times in any calendar year)\n50 % of limit value (10 μg/m3)\n(d) LEAD\nAnnual average\nUpper assessment threshold\n70 % of limit value (0.35 μg/m3 )\nLower assessment threshold\n50 % of limit value (0.25 μg/m3 )",
  "extent": null,
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "The upper and lower assessment thresholds for PM10 are based on the following indicative limit values for 1 January 2010, which will be reviewed in the light of further information on health and environmental effects, technical feasibility and experience in the application of the existing “Stage 1” limit values: Averaging PeriodLimit valueMargin of toleranceDate by which limit value is to be met 1 24-hour limit value for the protection of human health 24 hours50μg/m3 PM10 not to be exceeded more than 7 times a calendar yearTo be derived from date and to be equivalent to Stage 1 limit value1 January 20102 Annual limit value for the protection of human health Calendar year20μg/m3 PM1050% on 1 January 2005 reducing every 12 months thereafter by equal percentages to reach 0% by 1 January 20101 January 2010"
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/wsi/2001/2683/schedule/2/part/I",
    "retrieved_at": "2026-10-29T00:15:58.976500+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."
}