{
  "schemaVersion": 1,
  "slug": "uv-index-exposure-time-calculator",
  "category": "weather",
  "kind": "implementation",
  "independentValidation": false,
  "implementationHash": "6c251eadcaec5f64aad0819ac691594391fb10fa309080f20f08c886ea8329c5",
  "provenance": "Generated from the calculation contract used by the published page. Publication is not external validation.",
  "sourceFiles": [
    "data/calculators/uv-index-exposure-time-calculator.json",
    "src/engine.js"
  ],
  "runtimeSource": "/sources/engine.txt",
  "runtimeHash": "5c888d8898afbdee36267bb9977829e1e2ac568f6677c8ee87469c139864645c",
  "scope": "The compute function records implemented equations, constants, lookup tables and custom rules. Inputs record defaults and allowed values; outputs record precision and units. Defaults are examples, not recommendations. General background references are not evidence for this specific algorithm.",
  "publishedFormula": {
    "formula": "E_eff = UVI÷40; H = E_eff×t×60",
    "vars": [
      [
        "UVI",
        "UV Index"
      ],
      [
        "E_eff",
        "Erythemally weighted ambient irradiance (W/m²)"
      ],
      [
        "t",
        "Exposure duration (min)"
      ],
      [
        "H",
        "Incident ambient radiant exposure (J/m²)"
      ]
    ],
    "note": "UVI = 40×E_eff (W/m²); H = E_eff×t×60 (J/m²). H is incident ambient erythemally weighted radiant exposure, not absorbed personal dose or a safe-time limit. See WHO UV Index guidance: https://www.who.int/news-room/fact-sheets/detail/ultraviolet-radiation."
  },
  "externalEvidence": null,
  "contract": {
    "compute": "const irradiance=uvIndex/40;const exposure=irradiance*durationMinutes*60;return {uvIrradiance:irradiance,ambientExposure:exposure,category:uvIndex<3?'Low':uvIndex<6?'Moderate':uvIndex<8?'High':uvIndex<11?'Very high':'Extreme'};",
    "inputs": [
      {
        "name": "uvIndex",
        "type": "number",
        "default": 8,
        "min": 0,
        "max": 16,
        "step": 0.5,
        "slider": true
      },
      {
        "name": "durationMinutes",
        "type": "number",
        "default": 10,
        "min": 1,
        "max": 1440,
        "step": 1,
        "slider": true
      }
    ],
    "outputs": [
      {
        "name": "uvIrradiance",
        "precision": 4,
        "unit": "W/m²"
      },
      {
        "name": "ambientExposure",
        "precision": 1,
        "unit": "J/m²"
      },
      {
        "name": "category",
        "precision": 0,
        "unit": "",
        "type": "text"
      }
    ],
    "interpret": null
  }
}