SmogRank / Episodes / United States
Northern United States, January 2023
For 5 days, from 7 to 11 January 2023, 32 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Saint Paul, Minnesota, United States: 64.4 µg/m³ on 10 January, about 11× its usual 6.0.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 32 in 1 country
Days 5 7 to 11 January 2023
Worst day 11 January 21 cities counted
Furthest above usual 11× Saint Paul
Day by day
Play 11 January 21 cities at twice their usual or more
La Crosse Clinton Rockford Davenport Moline Muscatine Duluth Naperville Northbrook Joliet Oak Lawn Chicago Calumet City Hammond East Chicago Gary Portage Holland South Bend Grand Rapids Elkhart Omaha Sioux Falls Brookings Lansing Sault Ste. Marie Bay City Flint Ypsilanti Toledo Taylor Dearborn Lincoln Park Detroit Port Huron Sarnia Redford Waterloo Franklin Park South Milwaukee Des Plaines Kalamazoo Iowa City Madison Jenison Cary Cedar Rapids Waukesha Milwaukee Zion Green Bay Appleton Aberdeen Des Moines Watertown Rochester Ankeny Superior Eau Claire West Fargo Blaine Burnsville Saint Cloud Saint Michael Minneapolis Shakopee Apple Valley Saint Paul 4 Jan 5 6 7 8 9 10 11 12 13 14 Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.
How it spread
Saint Paul Saint Paul, 4 January: 2.3 µg/m³, 0.4× usual Saint Paul, 5 January: 4.9 µg/m³, 0.8× usual Saint Paul, 6 January: 17.4 µg/m³, 2.9× usual Saint Paul, 7 January: 42.4 µg/m³, 7.1× usual Saint Paul, 8 January: 38.6 µg/m³, 6.4× usual Saint Paul, 9 January: 31.1 µg/m³, 5.2× usual Saint Paul, 10 January: 64.4 µg/m³, 11× usual Saint Paul, 11 January: 42.7 µg/m³, 7.1× usual Saint Paul, 12 January: 14.4 µg/m³, 2.4× usual Saint Paul, 13 January: 9.9 µg/m³, 1.7× usual Saint Paul, 14 January: 10.1 µg/m³, 1.7× usual Minneapolis Minneapolis, 4 January: 3.4 µg/m³, 0.5× usual Minneapolis, 5 January: 7.2 µg/m³, 1.1× usual Minneapolis, 6 January: 17.8 µg/m³, 2.7× usual Minneapolis, 7 January: 36.7 µg/m³, 5.6× usual Minneapolis, 8 January: 34.1 µg/m³, 5.2× usual Minneapolis, 9 January: 31.3 µg/m³, 4.8× usual Minneapolis, 10 January: 52.1 µg/m³, 8.0× usual Minneapolis, 11 January: 40.3 µg/m³, 6.2× usual Minneapolis, 12 January: 13.5 µg/m³, 2.1× usual Minneapolis, 13 January: 9.5 µg/m³, 1.5× usual Minneapolis, 14 January: 10.0 µg/m³, 1.5× usual Rochester Rochester, 4 January: 5.2 µg/m³, 0.8× usual Rochester, 5 January: 6.4 µg/m³, 1.0× usual Rochester, 6 January: 15.3 µg/m³, 2.4× usual Rochester, 7 January: 34.8 µg/m³, 5.4× usual Rochester, 8 January: 29.7 µg/m³, 4.6× usual Rochester, 9 January: 22.4 µg/m³, 3.4× usual Rochester, 10 January: 35.4 µg/m³, 5.4× usual Rochester, 11 January: no reading Rochester, 12 January: no reading Rochester, 13 January: no reading Rochester, 14 January: no reading Shakopee Shakopee, 4 January: 2.8 µg/m³, 0.5× usual Shakopee, 5 January: 6.0 µg/m³, 1.0× usual Shakopee, 6 January: 22.2 µg/m³, 3.8× usual Shakopee, 7 January: 33.8 µg/m³, 5.7× usual Shakopee, 8 January: 34.6 µg/m³, 5.9× usual Shakopee, 9 January: 33.5 µg/m³, 5.7× usual Shakopee, 10 January: 57.8 µg/m³, 9.8× usual Shakopee, 11 January: no reading Shakopee, 12 January: no reading Shakopee, 13 January: no reading Shakopee, 14 January: no reading Saint Michael Saint Michael, 4 January: no reading Saint Michael, 5 January: no reading Saint Michael, 6 January: 21.9 µg/m³, 3.9× usual Saint Michael, 7 January: 33.5 µg/m³, 6.0× usual Saint Michael, 8 January: no reading Saint Michael, 9 January: no reading Saint Michael, 10 January: no reading Saint Michael, 11 January: 43.1 µg/m³, 7.7× usual Saint Michael, 12 January: 9.6 µg/m³, 1.7× usual Saint Michael, 13 January: 7.7 µg/m³, 1.4× usual Saint Michael, 14 January: 10.1 µg/m³, 1.8× usual Apple Valley Apple Valley, 4 January: 4.5 µg/m³, 0.8× usual Apple Valley, 5 January: 6.6 µg/m³, 1.2× usual Apple Valley, 6 January: 19.4 µg/m³, 3.5× usual Apple Valley, 7 January: 31.4 µg/m³, 5.7× usual Apple Valley, 8 January: 29.7 µg/m³, 5.4× usual Apple Valley, 9 January: 28.7 µg/m³, 5.2× usual Apple Valley, 10 January: 54.0 µg/m³, 9.8× usual Apple Valley, 11 January: 43.5 µg/m³, 7.9× usual Apple Valley, 12 January: 13.6 µg/m³, 2.5× usual Apple Valley, 13 January: 10.1 µg/m³, 1.8× usual Apple Valley, 14 January: 10.2 µg/m³, 1.9× usual Eau Claire Eau Claire, 4 January: 2.7 µg/m³, 0.4× usual Eau Claire, 5 January: 3.1 µg/m³, 0.5× usual Eau Claire, 6 January: 13.0 µg/m³, 2.0× usual Eau Claire, 7 January: 31.4 µg/m³, 4.8× usual Eau Claire, 8 January: 23.8 µg/m³, 3.7× usual Eau Claire, 9 January: 28.6 µg/m³, 4.4× usual Eau Claire, 10 January: 41.0 µg/m³, 6.3× usual Eau Claire, 11 January: 36.9 µg/m³, 5.7× usual Eau Claire, 12 January: 12.2 µg/m³, 1.9× usual Eau Claire, 13 January: 4.6 µg/m³, 0.7× usual Eau Claire, 14 January: 6.9 µg/m³, 1.1× usual Saint Cloud Saint Cloud, 4 January: 3.5 µg/m³, 0.6× usual Saint Cloud, 5 January: 6.2 µg/m³, 1.1× usual Saint Cloud, 6 January: 18.5 µg/m³, 3.4× usual Saint Cloud, 7 January: 29.3 µg/m³, 5.4× usual Saint Cloud, 8 January: 25.4 µg/m³, 4.7× usual Saint Cloud, 9 January: 39.6 µg/m³, 7.3× usual Saint Cloud, 10 January: 35.0 µg/m³, 6.5× usual Saint Cloud, 11 January: 30.0 µg/m³, 5.6× usual Saint Cloud, 12 January: 7.1 µg/m³, 1.3× usual Saint Cloud, 13 January: 7.4 µg/m³, 1.4× usual Saint Cloud, 14 January: 10.0 µg/m³, 1.9× usual Des Moines Des Moines, 4 January: 8.9 µg/m³, 1.7× usual Des Moines, 5 January: 5.9 µg/m³, 1.1× usual Des Moines, 6 January: 14.3 µg/m³, 2.7× usual Des Moines, 7 January: 27.8 µg/m³, 5.2× usual Des Moines, 8 January: no reading Des Moines, 9 January: 12.2 µg/m³, 2.3× usual Des Moines, 10 January: 11.5 µg/m³, 2.2× usual Des Moines, 11 January: 18.1 µg/m³, 3.4× usual Des Moines, 12 January: 9.2 µg/m³, 1.7× usual Des Moines, 13 January: 5.6 µg/m³, 1.1× usual Des Moines, 14 January: 7.1 µg/m³, 1.3× usual Ankeny Ankeny, 4 January: 9.2 µg/m³, 1.8× usual Ankeny, 5 January: 5.5 µg/m³, 1.1× usual Ankeny, 6 January: 15.0 µg/m³, 3.0× usual Ankeny, 7 January: 27.1 µg/m³, 5.4× usual Ankeny, 8 January: 23.7 µg/m³, 4.7× usual Ankeny, 9 January: 14.2 µg/m³, 2.8× usual Ankeny, 10 January: 12.7 µg/m³, 2.5× usual Ankeny, 11 January: 19.8 µg/m³, 4.0× usual Ankeny, 12 January: 10.0 µg/m³, 2.0× usual Ankeny, 13 January: 5.3 µg/m³, 1.1× usual Ankeny, 14 January: 8.8 µg/m³, 1.8× usual Waterloo Waterloo, 4 January: 7.6 µg/m³, 0.8× usual Waterloo, 5 January: 7.0 µg/m³, 0.8× usual Waterloo, 6 January: 15.4 µg/m³, 1.7× usual Waterloo, 7 January: 26.0 µg/m³, 2.8× usual Waterloo, 8 January: 21.6 µg/m³, 2.3× usual Waterloo, 9 January: 19.6 µg/m³, 2.1× usual Waterloo, 10 January: 18.1 µg/m³, 1.9× usual Waterloo, 11 January: no reading Waterloo, 12 January: no reading Waterloo, 13 January: no reading Waterloo, 14 January: no reading West Fargo West Fargo, 4 January: 19.5 µg/m³, 3.9× usual West Fargo, 5 January: 17.8 µg/m³, 3.6× usual West Fargo, 6 January: 23.5 µg/m³, 4.7× usual West Fargo, 7 January: 23.4 µg/m³, 4.7× usual West Fargo, 8 January: 33.0 µg/m³, 6.6× usual West Fargo, 9 January: no reading West Fargo, 10 January: no reading West Fargo, 11 January: 27.4 µg/m³, 5.5× usual West Fargo, 12 January: 6.6 µg/m³, 1.3× usual West Fargo, 13 January: 10.1 µg/m³, 2.0× usual West Fargo, 14 January: 16.9 µg/m³, 3.4× usual Watertown Watertown, 4 January: 5.0 µg/m³, 0.9× usual Watertown, 5 January: 9.0 µg/m³, 1.6× usual Watertown, 6 January: 19.8 µg/m³, 3.5× usual Watertown, 7 January: 19.1 µg/m³, 3.4× usual Watertown, 8 January: 29.5 µg/m³, 5.3× usual Watertown, 9 January: 16.9 µg/m³, 3.0× usual Watertown, 10 January: 10.4 µg/m³, 1.9× usual Watertown, 11 January: 12.6 µg/m³, 2.3× usual Watertown, 12 January: 7.3 µg/m³, 1.3× usual Watertown, 13 January: 5.4 µg/m³, 1.0× usual Watertown, 14 January: 10.9 µg/m³, 1.9× usual Superior Superior, 4 January: 3.4 µg/m³, 0.7× usual Superior, 5 January: 3.0 µg/m³, 0.6× usual Superior, 6 January: 5.1 µg/m³, 1.0× usual Superior, 7 January: 6.8 µg/m³, 1.4× usual Superior, 8 January: 26.8 µg/m³, 5.4× usual Superior, 9 January: 28.8 µg/m³, 5.8× usual Superior, 10 January: 17.7 µg/m³, 3.5× usual Superior, 11 January: 17.6 µg/m³, 3.5× usual Superior, 12 January: 5.6 µg/m³, 1.1× usual Superior, 13 January: 3.7 µg/m³, 0.7× usual Superior, 14 January: 7.3 µg/m³, 1.5× usual Aberdeen Aberdeen, 4 January: no reading Aberdeen, 5 January: no reading Aberdeen, 6 January: 10.6 µg/m³, 2.1× usual Aberdeen, 7 January: 12.7 µg/m³, 2.5× usual Aberdeen, 8 January: 25.9 µg/m³, 5.2× usual Aberdeen, 9 January: 13.6 µg/m³, 2.7× usual Aberdeen, 10 January: 8.1 µg/m³, 1.6× usual Aberdeen, 11 January: 9.3 µg/m³, 1.9× usual Aberdeen, 12 January: 6.2 µg/m³, 1.2× usual Aberdeen, 13 January: 5.4 µg/m³, 1.1× usual Aberdeen, 14 January: 9.0 µg/m³, 1.8× usual Blaine Blaine, 4 January: no reading Blaine, 5 January: 2.4 µg/m³, 0.4× usual Blaine, 6 January: 1.6 µg/m³, 0.3× usual Blaine, 7 January: 1.3 µg/m³, 0.2× usual Blaine, 8 January: 1.2 µg/m³, 0.2× usual Blaine, 9 January: 12.4 µg/m³, 2.2× usual Blaine, 10 January: 37.9 µg/m³, 6.8× usual Blaine, 11 January: no reading Blaine, 12 January: no reading Blaine, 13 January: no reading Blaine, 14 January: no reading Appleton Appleton, 4 January: 7.8 µg/m³, 1.4× usual Appleton, 5 January: 6.3 µg/m³, 1.1× usual Appleton, 6 January: 4.3 µg/m³, 0.8× usual Appleton, 7 January: 7.1 µg/m³, 1.2× usual Appleton, 8 January: 14.6 µg/m³, 2.6× usual Appleton, 9 January: 24.4 µg/m³, 4.3× usual Appleton, 10 January: 28.3 µg/m³, 5.0× usual Appleton, 11 January: 24.7 µg/m³, 4.3× usual Appleton, 12 January: 6.0 µg/m³, 1.1× usual Appleton, 13 January: 1.9 µg/m³, 0.3× usual Appleton, 14 January: 8.2 µg/m³, 1.4× usual Green Bay Green Bay, 4 January: 7.6 µg/m³, 1.4× usual Green Bay, 5 January: 5.4 µg/m³, 1.0× usual Green Bay, 6 January: 4.1 µg/m³, 0.7× usual Green Bay, 7 January: 7.5 µg/m³, 1.3× usual Green Bay, 8 January: 14.4 µg/m³, 2.6× usual Green Bay, 9 January: 23.5 µg/m³, 4.2× usual Green Bay, 10 January: 27.7 µg/m³, 4.9× usual Green Bay, 11 January: no reading Green Bay, 12 January: no reading Green Bay, 13 January: no reading Green Bay, 14 January: no reading Redford Redford, 4 January: 13.6 µg/m³, 1.0× usual Redford, 5 January: 11.4 µg/m³, 0.9× usual Redford, 6 January: 16.0 µg/m³, 1.2× usual Redford, 7 January: 8.8 µg/m³, 0.7× usual Redford, 8 January: 12.5 µg/m³, 0.9× usual Redford, 9 January: 17.5 µg/m³, 1.3× usual Redford, 10 January: 26.6 µg/m³, 2.0× usual Redford, 11 January: 28.1 µg/m³, 2.1× usual Redford, 12 January: 19.5 µg/m³, 1.5× usual Redford, 13 January: 6.2 µg/m³, 0.5× usual Redford, 14 January: 7.1 µg/m³, 0.5× usual Burnsville Burnsville, 4 January: no reading Burnsville, 5 January: no reading Burnsville, 6 January: no reading Burnsville, 7 January: no reading Burnsville, 8 January: no reading Burnsville, 9 January: no reading Burnsville, 10 January: no reading Burnsville, 11 January: 43.5 µg/m³, 7.0× usual Burnsville, 12 January: 14.2 µg/m³, 2.3× usual Burnsville, 13 January: 10.1 µg/m³, 1.6× usual Burnsville, 14 January: 9.8 µg/m³, 1.6× usual Waukesha Waukesha, 4 January: 9.3 µg/m³, 1.4× usual Waukesha, 5 January: 14.9 µg/m³, 2.2× usual Waukesha, 6 January: 7.5 µg/m³, 1.1× usual Waukesha, 7 January: 9.6 µg/m³, 1.4× usual Waukesha, 8 January: 13.3 µg/m³, 2.0× usual Waukesha, 9 January: 20.7 µg/m³, 3.1× usual Waukesha, 10 January: 24.9 µg/m³, 3.7× usual Waukesha, 11 January: 30.2 µg/m³, 4.5× usual Waukesha, 12 January: 9.4 µg/m³, 1.4× usual Waukesha, 13 January: 3.2 µg/m³, 0.5× usual Waukesha, 14 January: 9.1 µg/m³, 1.4× usual Milwaukee Milwaukee, 4 January: no reading Milwaukee, 5 January: no reading Milwaukee, 6 January: no reading Milwaukee, 7 January: no reading Milwaukee, 8 January: no reading Milwaukee, 9 January: no reading Milwaukee, 10 January: no reading Milwaukee, 11 January: 30.0 µg/m³, 4.6× usual Milwaukee, 12 January: 10.0 µg/m³, 1.5× usual Milwaukee, 13 January: 3.6 µg/m³, 0.6× usual Milwaukee, 14 January: 9.3 µg/m³, 1.4× usual South Milwaukee South Milwaukee, 4 January: 9.9 µg/m³, 1.3× usual South Milwaukee, 5 January: 15.2 µg/m³, 1.9× usual South Milwaukee, 6 January: 7.6 µg/m³, 1.0× usual South Milwaukee, 7 January: 9.8 µg/m³, 1.2× usual South Milwaukee, 8 January: 12.6 µg/m³, 1.6× usual South Milwaukee, 9 January: 19.1 µg/m³, 2.4× usual South Milwaukee, 10 January: 21.2 µg/m³, 2.7× usual South Milwaukee, 11 January: 28.5 µg/m³, 3.6× usual South Milwaukee, 12 January: 10.4 µg/m³, 1.3× usual South Milwaukee, 13 January: 4.1 µg/m³, 0.5× usual South Milwaukee, 14 January: 9.3 µg/m³, 1.2× usual Kalamazoo Kalamazoo, 4 January: 10.4 µg/m³, 1.4× usual Kalamazoo, 5 January: 12.1 µg/m³, 1.6× usual Kalamazoo, 6 January: 12.5 µg/m³, 1.6× usual Kalamazoo, 7 January: 11.3 µg/m³, 1.5× usual Kalamazoo, 8 January: 12.7 µg/m³, 1.7× usual Kalamazoo, 9 January: 18.6 µg/m³, 2.4× usual Kalamazoo, 10 January: 21.4 µg/m³, 2.8× usual Kalamazoo, 11 January: 28.4 µg/m³, 3.7× usual Kalamazoo, 12 January: 23.9 µg/m³, 3.1× usual Kalamazoo, 13 January: 4.3 µg/m³, 0.6× usual Kalamazoo, 14 January: 6.4 µg/m³, 0.8× usual Madison Madison, 4 January: 9.1 µg/m³, 1.4× usual Madison, 5 January: 10.2 µg/m³, 1.6× usual Madison, 6 January: 10.4 µg/m³, 1.6× usual Madison, 7 January: 11.2 µg/m³, 1.7× usual Madison, 8 January: 12.8 µg/m³, 2.0× usual Madison, 9 January: 21.2 µg/m³, 3.3× usual Madison, 10 January: 22.2 µg/m³, 3.5× usual Madison, 11 January: 26.8 µg/m³, 4.2× usual Madison, 12 January: 11.8 µg/m³, 1.8× usual Madison, 13 January: 4.1 µg/m³, 0.6× usual Madison, 14 January: 7.8 µg/m³, 1.2× usual Iowa City Iowa City, 4 January: no reading Iowa City, 5 January: no reading Iowa City, 6 January: no reading Iowa City, 7 January: no reading Iowa City, 8 January: no reading Iowa City, 9 January: no reading Iowa City, 10 January: no reading Iowa City, 11 January: 26.7 µg/m³, 3.9× usual Iowa City, 12 January: 22.9 µg/m³, 3.3× usual Iowa City, 13 January: 7.6 µg/m³, 1.1× usual Iowa City, 14 January: 9.6 µg/m³, 1.4× usual Jenison Jenison, 4 January: 8.8 µg/m³, 1.4× usual Jenison, 5 January: 11.3 µg/m³, 1.8× usual Jenison, 6 January: 7.3 µg/m³, 1.2× usual Jenison, 7 January: 5.1 µg/m³, 0.8× usual Jenison, 8 January: 11.5 µg/m³, 1.8× usual Jenison, 9 January: 17.9 µg/m³, 2.8× usual Jenison, 10 January: 20.5 µg/m³, 3.3× usual Jenison, 11 January: 26.3 µg/m³, 4.2× usual Jenison, 12 January: 14.4 µg/m³, 2.3× usual Jenison, 13 January: 2.2 µg/m³, 0.3× usual Jenison, 14 January: 5.4 µg/m³, 0.9× usual Zion Zion, 4 January: 7.8 µg/m³, 1.4× usual Zion, 5 January: 13.4 µg/m³, 2.4× usual Zion, 6 January: 7.1 µg/m³, 1.3× usual Zion, 7 January: 9.8 µg/m³, 1.8× usual Zion, 8 January: 12.0 µg/m³, 2.1× usual Zion, 9 January: 18.7 µg/m³, 3.3× usual Zion, 10 January: 18.1 µg/m³, 3.2× usual Zion, 11 January: 25.9 µg/m³, 4.6× usual Zion, 12 January: 10.5 µg/m³, 1.9× usual Zion, 13 January: 3.5 µg/m³, 0.6× usual Zion, 14 January: 8.3 µg/m³, 1.5× usual Franklin Park Franklin Park, 4 January: 8.3 µg/m³, 1.0× usual Franklin Park, 5 January: 13.1 µg/m³, 1.5× usual Franklin Park, 6 January: 9.2 µg/m³, 1.1× usual Franklin Park, 7 January: 10.7 µg/m³, 1.2× usual Franklin Park, 8 January: 14.4 µg/m³, 1.7× usual Franklin Park, 9 January: 19.7 µg/m³, 2.3× usual Franklin Park, 10 January: 19.2 µg/m³, 2.2× usual Franklin Park, 11 January: 25.8 µg/m³, 3.0× usual Franklin Park, 12 January: 13.7 µg/m³, 1.6× usual Franklin Park, 13 January: 4.8 µg/m³, 0.6× usual Franklin Park, 14 January: 8.8 µg/m³, 1.0× usual Cedar Rapids Cedar Rapids, 4 January: no reading Cedar Rapids, 5 January: no reading Cedar Rapids, 6 January: no reading Cedar Rapids, 7 January: no reading Cedar Rapids, 8 January: no reading Cedar Rapids, 9 January: no reading Cedar Rapids, 10 January: no reading Cedar Rapids, 11 January: 25.5 µg/m³, 4.3× usual Cedar Rapids, 12 January: 19.4 µg/m³, 3.3× usual Cedar Rapids, 13 January: 6.6 µg/m³, 1.1× usual Cedar Rapids, 14 January: 10.2 µg/m³, 1.7× usual Cary Cary, 4 January: 8.5 µg/m³, 1.4× usual Cary, 5 January: 13.3 µg/m³, 2.3× usual Cary, 6 January: 7.5 µg/m³, 1.3× usual Cary, 7 January: 11.6 µg/m³, 2.0× usual Cary, 8 January: 11.6 µg/m³, 2.0× usual Cary, 9 January: 19.3 µg/m³, 3.3× usual Cary, 10 January: 18.7 µg/m³, 3.2× usual Cary, 11 January: 25.3 µg/m³, 4.3× usual Cary, 12 January: 12.7 µg/m³, 2.2× usual Cary, 13 January: 3.0 µg/m³, 0.5× usual Cary, 14 January: 8.4 µg/m³, 1.4× usual Des Plaines Des Plaines, 4 January: 8.2 µg/m³, 1.2× usual Des Plaines, 5 January: 13.1 µg/m³, 1.9× usual Des Plaines, 6 January: 8.3 µg/m³, 1.2× usual Des Plaines, 7 January: 11.0 µg/m³, 1.6× usual Des Plaines, 8 January: 14.9 µg/m³, 2.1× usual Des Plaines, 9 January: 20.1 µg/m³, 2.9× usual Des Plaines, 10 January: 18.3 µg/m³, 2.6× usual Des Plaines, 11 January: 25.3 µg/m³, 3.6× usual Des Plaines, 12 January: 12.7 µg/m³, 1.8× usual Des Plaines, 13 January: 3.9 µg/m³, 0.6× usual Des Plaines, 14 January: 9.1 µg/m³, 1.3× usual 4 Jan 6 8 10 12 14 Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Saint Paul Minnesota, United States 5 10 January 6.0 11× Apple Valley Minnesota, United States 5 10 January 5.5 9.8× Shakopee Minnesota, United States 4 10 January 5.9 9.8× Minneapolis Minnesota, United States 5 10 January 6.5 8.0× Saint Michael Minnesota, United States 2 11 January 5.6 7.7× Saint Cloud Minnesota, United States 5 9 January 5.4 7.3× Burnsville Minnesota, United States 1 11 January 6.2 7.0× Blaine Minnesota, United States 1 10 January 5.6 6.8× West Fargo North Dakota, United States 2 8 January 4.4 6.6× Eau Claire Wisconsin, United States 4 10 January 6.5 6.3× Superior Wisconsin, United States 2 9 January 4.9 5.8× Rochester Minnesota, United States 3 10 January 6.5 5.4× Ankeny Iowa, United States 1 7 January 4.8 5.4× Watertown South Dakota, United States 1 8 January 5.6 5.3× Des Moines Iowa, United States 1 7 January 5.3 5.2× Aberdeen South Dakota, United States 1 8 January 4.6 5.2× Appleton Wisconsin, United States 1 10 January 5.7 5.0× Green Bay Wisconsin, United States 1 10 January 5.6 4.9× Zion Illinois, United States 1 11 January 5.6 4.6× Milwaukee Wisconsin, United States 1 11 January 6.5 4.6× Waukesha Wisconsin, United States 1 11 January 6.7 4.5× Cedar Rapids Iowa, United States 1 11 January 5.9 4.3× Cary Illinois, United States 1 11 January 5.9 4.3× Madison Wisconsin, United States 1 11 January 6.4 4.2× Jenison Michigan, United States 1 11 January 6.3 4.2× Iowa City Iowa, United States 1 11 January 6.9 3.9× Kalamazoo Michigan, United States 1 11 January 7.6 3.7× Des Plaines Illinois, United States 1 11 January 7.0 3.6× South Milwaukee Wisconsin, United States 1 11 January 7.9 3.6× Franklin Park Illinois, United States 1 11 January 8.7 3.0× Waterloo Iowa, United States 1 7 January 9.3 2.8× Redford Michigan, United States 1 11 January 13.4 2.1×
Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.
Against other episodes in the United States
Number 12 of 41 episodes in the United States since our records began, by cities reached.
North-eastern United States and Canada, June and July 2023 279 North-eastern United States and Canada, May and June 2023 260 North-eastern United States and Canada, July 2023 241 North-eastern United States and Canada, June 2023 161 North-western United States and Canada, August 2023 110 North-eastern United States and Canada, July 2023 75 Western United States, September 2023 61 South-eastern United States, October 2023 47 North-eastern United States, July 2023 46 North-western United States and Canada, May 2023 42 Western United States, December 2023 32 Northern United States, January 2023 32 Bars: cities reached; colour: the level of the episode's highest daily reading. All 41 .
Use this page SmogRank, Northern United States, January 2023: 32 cities with PM2.5 at twice their usual or more, 7 to 11 January 2023, smogrank.com/episodes/2023-01-northern-united-states (accessed 2 October 2026).
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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms .
An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes . Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.
