{
 "topic": "air",
 "site": "airdata.dev",
 "place": {
  "id": "us-county-27053",
  "name": "Hennepin County",
  "level": "us-county",
  "parent": "us-mn",
  "path": "us/mn/hennepin-county",
  "slug": "hennepin-county",
  "state": "mn",
  "state_name": "Minnesota",
  "state_id": "us-mn"
 },
 "question": "How many bad-air days did Hennepin County have?",
 "answer": {
  "verdict": "More bad-air days than usual",
  "value": 10,
  "unit": " days",
  "digits": 0,
  "label": "Bad-air days in 2025",
  "lines": [
   "Average of the ten years before: 3.3 days (2015–2024)",
   "Fine particles (PM2.5, including wildfire smoke) were the main pollutant on 78% of days, ozone on 17%"
  ]
 },
 "as_of": "2025",
 "as_of_label": "2025",
 "charts": [
  {
   "id": "air-history",
   "title": "Bad-air days each year since 1980",
   "description": "2025 had 10 bad-air days, against an average of 3.3 a year in 2015–2024; the most since 1980 was 19 (1980).",
   "indicator": "Days a year with a county AQI above 100 (unhealthy for sensitive groups or worse), EPA AQS annual summary",
   "subtitle": "Days with an AQI above 100 (unhealthy for sensitive groups or worse). 2025 is highlighted.",
   "x": {
    "kind": "year"
   },
   "y": {
    "digits": 0,
    "unit": " days"
   },
   "layers": [
    {
     "type": "bars",
     "name": "Bad-air days",
     "base": 0,
     "points": [
      [
       1980,
       19,
       "ctx"
      ],
      [
       1981,
       9,
       "ctx"
      ],
      [
       1982,
       0,
       "ctx"
      ],
      [
       1983,
       2,
       "ctx"
      ],
      [
       1984,
       0,
       "ctx"
      ],
      [
       1985,
       0,
       "ctx"
      ],
      [
       1986,
       3,
       "ctx"
      ],
      [
       1987,
       6,
       "ctx"
      ],
      [
       1988,
       13,
       "ctx"
      ],
      [
       1989,
       9,
       "ctx"
      ],
      [
       1990,
       2,
       "ctx"
      ],
      [
       1991,
       1,
       "ctx"
      ],
      [
       1992,
       2,
       "ctx"
      ],
      [
       1993,
       2,
       "ctx"
      ],
      [
       1994,
       0,
       "ctx"
      ],
      [
       1995,
       0,
       "ctx"
      ],
      [
       1996,
       0,
       "ctx"
      ],
      [
       1997,
       0,
       "ctx"
      ],
      [
       1998,
       2,
       "ctx"
      ],
      [
       1999,
       2,
       "ctx"
      ],
      [
       2000,
       9,
       "ctx"
      ],
      [
       2001,
       5,
       "ctx"
      ],
      [
       2002,
       1,
       "ctx"
      ],
      [
       2003,
       4,
       "ctx"
      ],
      [
       2004,
       3,
       "ctx"
      ],
      [
       2005,
       6,
       "ctx"
      ],
      [
       2006,
       2,
       "ctx"
      ],
      [
       2007,
       5,
       "ctx"
      ],
      [
       2008,
       4,
       "ctx"
      ],
      [
       2009,
       3,
       "ctx"
      ],
      [
       2010,
       3,
       "ctx"
      ],
      [
       2011,
       0,
       "ctx"
      ],
      [
       2012,
       1,
       "ctx"
      ],
      [
       2013,
       0,
       "ctx"
      ],
      [
       2014,
       0,
       "ctx"
      ],
      [
       2015,
       3,
       "ctx"
      ],
      [
       2016,
       2,
       "ctx"
      ],
      [
       2017,
       1,
       "ctx"
      ],
      [
       2018,
       1,
       "ctx"
      ],
      [
       2019,
       0,
       "ctx"
      ],
      [
       2020,
       2,
       "ctx"
      ],
      [
       2021,
       3,
       "ctx"
      ],
      [
       2022,
       0,
       "ctx"
      ],
      [
       2023,
       17,
       "ctx"
      ],
      [
       2024,
       4,
       "ctx"
      ],
      [
       2025,
       10,
       "s1"
      ]
     ]
    },
    {
     "type": "rule",
     "name": "2015–2024 average",
     "y": 3.3,
     "label": "10-year average 3.3",
     "label_at": "start"
    }
   ]
  }
 ],
 "limits": [
  "The county's worst monitor sets each day's AQI, so a reading near a highway can stand for the whole county.",
  "2026 counts are partial and include data EPA has not finished validating."
 ],
 "method": "A bad-air day has an AQI above 100. 2025 is compared with the average of the ten years before: a difference of more than a quarter of that average (and at least three days) is 'more' or 'fewer'.",
 "sources": [
  {
   "name": "EPA Air Quality System, annual AQI by county",
   "url": "https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual",
   "license": "U.S. public domain"
  }
 ],
 "check": {
  "year": 2025,
  "by_year": {
   "1980": 19,
   "1981": 9,
   "1982": 0,
   "1983": 2,
   "1984": 0,
   "1985": 0,
   "1986": 3,
   "1987": 6,
   "1988": 13,
   "1989": 9,
   "1990": 2,
   "1991": 1,
   "1992": 2,
   "1993": 2,
   "1994": 0,
   "1995": 0,
   "1996": 0,
   "1997": 0,
   "1998": 2,
   "1999": 2,
   "2000": 9,
   "2001": 5,
   "2002": 1,
   "2003": 4,
   "2004": 3,
   "2005": 6,
   "2006": 2,
   "2007": 5,
   "2008": 4,
   "2009": 3,
   "2010": 3,
   "2011": 0,
   "2012": 1,
   "2013": 0,
   "2014": 0,
   "2015": 3,
   "2016": 2,
   "2017": 1,
   "2018": 1,
   "2019": 0,
   "2020": 2,
   "2021": 3,
   "2022": 0,
   "2023": 17,
   "2024": 4,
   "2025": 10
  },
  "prior": [
   2015,
   2016,
   2017,
   2018,
   2019,
   2020,
   2021,
   2022,
   2023,
   2024
  ],
  "average": 3.3
 },
 "parts": {
  "title": "Every day of 2025, by AQI category",
  "total": 365,
  "items": [
   {
    "label": "Good",
    "days": 211,
    "cls": "good"
   },
   {
    "label": "Moderate",
    "days": 144,
    "cls": "moderate"
   },
   {
    "label": "Unhealthy for sensitive groups",
    "days": 4,
    "cls": "usg"
   },
   {
    "label": "Unhealthy",
    "days": 6,
    "cls": "unhealthy"
   },
   {
    "label": "Very unhealthy",
    "days": 0,
    "cls": "very"
   },
   {
    "label": "Hazardous",
    "days": 0,
    "cls": "hazardous"
   }
  ]
 },
 "generated_at": "2026-10-24T18:00:52+00:00"
}