SmogRank / Episodes / United States
North-eastern United States, June 2023
For 2 days, from 22 to 23 June 2023, 18 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Green Bay, Wisconsin, United States: 51.1 µg/m³ on 23 June, about 7.1× its usual 7.2.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 18 in 1 country
Days 2 22 to 23 June 2023
Worst day 23 June 18 cities counted
Furthest above usual 7.5× Appleton
Day by day
Play 23 June 18 cities at twice their usual or more
Franklin Park Oak Lawn Chicago Gary Portage Moline Davenport Muscatine South Bend Holland La Crosse Iowa City Lafayette Elkhart Jenison Grand Rapids Kalamazoo Kokomo Waterloo Eau Claire Anderson Rochester Lansing Ankeny Des Moines Saint Paul Apple Valley Burnsville Lima Bay City Flint Ypsilanti Shakopee Toledo Calumet City Hammond Cary Northbrook Des Plaines Naperville Clinton Joliet East Chicago Milwaukee Zion South Milwaukee Bloomington Rockford Waukesha Madison Green Bay Appleton 19 Jun 20 21 22 23 24 25 26 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
South Milwaukee South Milwaukee, 19 June: 28.1 µg/m³ South Milwaukee, 20 June: 25.2 µg/m³ South Milwaukee, 21 June: 21.5 µg/m³ South Milwaukee, 22 June: 28.1 µg/m³, 4.0× its usual 7.0 South Milwaukee, 23 June: 33.3 µg/m³, 4.7× its usual 7.1 South Milwaukee, 24 June: 15.4 µg/m³ South Milwaukee, 25 June: 13.4 µg/m³ South Milwaukee, 26 June: 47.1 µg/m³ Appleton Appleton, 19 June: 28.2 µg/m³ Appleton, 20 June: 23.1 µg/m³ Appleton, 21 June: 19.4 µg/m³ Appleton, 22 June: 27.7 µg/m³, 4.1× its usual 6.7 Appleton, 23 June: 50.8 µg/m³, 7.5× its usual 6.8 Appleton, 24 June: 35.7 µg/m³ Appleton, 25 June: 10.5 µg/m³ Appleton, 26 June: 67.7 µg/m³ Green Bay Green Bay, 19 June: 21.2 µg/m³ Green Bay, 20 June: 19.9 µg/m³ Green Bay, 21 June: 17.3 µg/m³ Green Bay, 22 June: 27.7 µg/m³, 3.9× its usual 7.1 Green Bay, 23 June: 51.1 µg/m³, 7.1× its usual 7.2 Green Bay, 24 June: 32.0 µg/m³ Green Bay, 25 June: 12.4 µg/m³ Green Bay, 26 June: 72.5 µg/m³ Milwaukee Milwaukee, 19 June: 28.7 µg/m³ Milwaukee, 20 June: 23.4 µg/m³ Milwaukee, 21 June: 21.0 µg/m³ Milwaukee, 22 June: 26.9 µg/m³, 3.2× its usual 8.4 Milwaukee, 23 June: 36.0 µg/m³, 4.3× its usual 8.4 Milwaukee, 24 June: 14.5 µg/m³ Milwaukee, 25 June: 10.9 µg/m³ Milwaukee, 26 June: 44.6 µg/m³ Waukesha Waukesha, 19 June: 29.2 µg/m³ Waukesha, 20 June: 22.1 µg/m³ Waukesha, 21 June: 20.8 µg/m³ Waukesha, 22 June: 26.2 µg/m³, 3.5× its usual 7.5 Waukesha, 23 June: 41.7 µg/m³, 5.3× its usual 7.8 Waukesha, 24 June: 20.3 µg/m³ Waukesha, 25 June: 9.9 µg/m³ Waukesha, 26 June: 42.6 µg/m³ Rockford Rockford, 19 June: 24.9 µg/m³ Rockford, 20 June: 20.2 µg/m³ Rockford, 21 June: 19.0 µg/m³ Rockford, 22 June: 20.6 µg/m³ Rockford, 23 June: 40.4 µg/m³, 5.1× its usual 8.0 Rockford, 24 June: 23.4 µg/m³ Rockford, 25 June: 8.5 µg/m³ Rockford, 26 June: 32.8 µg/m³ Madison Madison, 19 June: 26.9 µg/m³ Madison, 20 June: 22.0 µg/m³ Madison, 21 June: 19.3 µg/m³ Madison, 22 June: 21.1 µg/m³ Madison, 23 June: 39.5 µg/m³, 5.7× its usual 6.9 Madison, 24 June: 27.2 µg/m³ Madison, 25 June: 8.6 µg/m³ Madison, 26 June: 38.0 µg/m³ Bloomington Bloomington, 19 June: 25.2 µg/m³ Bloomington, 20 June: 22.3 µg/m³ Bloomington, 21 June: 17.1 µg/m³ Bloomington, 22 June: 20.9 µg/m³ Bloomington, 23 June: 39.0 µg/m³, 4.9× its usual 7.9 Bloomington, 24 June: 24.5 µg/m³ Bloomington, 25 June: 10.1 µg/m³ Bloomington, 26 June: 19.8 µg/m³ Joliet Joliet, 19 June: 27.9 µg/m³ Joliet, 20 June: 23.0 µg/m³ Joliet, 21 June: 22.5 µg/m³ Joliet, 22 June: 22.9 µg/m³ Joliet, 23 June: 32.8 µg/m³, 3.6× its usual 9.1 Joliet, 24 June: 23.5 µg/m³ Joliet, 25 June: 10.4 µg/m³ Joliet, 26 June: 32.7 µg/m³ Naperville Naperville, 19 June: 27.2 µg/m³ Naperville, 20 June: 21.9 µg/m³ Naperville, 21 June: 23.1 µg/m³ Naperville, 22 June: 22.9 µg/m³ Naperville, 23 June: 31.6 µg/m³, 3.4× its usual 9.4 Naperville, 24 June: 22.9 µg/m³ Naperville, 25 June: 11.0 µg/m³ Naperville, 26 June: 35.2 µg/m³ East Chicago East Chicago, 19 June: 22.1 µg/m³ East Chicago, 20 June: 22.9 µg/m³ East Chicago, 21 June: 20.7 µg/m³ East Chicago, 22 June: 22.1 µg/m³ East Chicago, 23 June: 28.7 µg/m³, 3.8× its usual 7.5 East Chicago, 24 June: 12.0 µg/m³ East Chicago, 25 June: 10.8 µg/m³ East Chicago, 26 June: 30.8 µg/m³ Zion Zion, 19 June: 20.1 µg/m³ Zion, 20 June: 20.1 µg/m³ Zion, 21 June: 15.6 µg/m³ Zion, 22 June: 20.8 µg/m³ Zion, 23 June: 28.5 µg/m³, 4.5× its usual 6.4 Zion, 24 June: 10.8 µg/m³ Zion, 25 June: 8.1 µg/m³ Zion, 26 June: 31.0 µg/m³ Des Plaines Des Plaines, 19 June: 24.5 µg/m³ Des Plaines, 20 June: 21.2 µg/m³ Des Plaines, 21 June: 20.1 µg/m³ Des Plaines, 22 June: 22.1 µg/m³ Des Plaines, 23 June: 28.3 µg/m³, 3.4× its usual 8.4 Des Plaines, 24 June: 14.6 µg/m³ Des Plaines, 25 June: 10.6 µg/m³ Des Plaines, 26 June: 33.1 µg/m³ Northbrook Northbrook, 19 June: 22.6 µg/m³ Northbrook, 20 June: 21.0 µg/m³ Northbrook, 21 June: 19.4 µg/m³ Northbrook, 22 June: 20.2 µg/m³ Northbrook, 23 June: 28.3 µg/m³, 3.4× its usual 8.4 Northbrook, 24 June: 11.0 µg/m³ Northbrook, 25 June: 11.6 µg/m³ Northbrook, 26 June: 34.0 µg/m³ Cary Cary, 19 June: 23.5 µg/m³ Cary, 20 June: 20.7 µg/m³ Cary, 21 June: 19.9 µg/m³ Cary, 22 June: 21.1 µg/m³ Cary, 23 June: 28.2 µg/m³, 3.4× its usual 8.4 Cary, 24 June: 17.3 µg/m³ Cary, 25 June: 9.3 µg/m³ Cary, 26 June: 32.6 µg/m³ Clinton Clinton, 19 June: 23.7 µg/m³ Clinton, 20 June: 19.4 µg/m³ Clinton, 21 June: 18.7 µg/m³ Clinton, 22 June: 19.0 µg/m³ Clinton, 23 June: 27.4 µg/m³, 3.6× its usual 7.7 Clinton, 24 June: 23.4 µg/m³ Clinton, 25 June: 6.9 µg/m³ Clinton, 26 June: 22.3 µg/m³ Hammond Hammond, 19 June: 25.5 µg/m³ Hammond, 20 June: 23.9 µg/m³ Hammond, 21 June: 23.7 µg/m³ Hammond, 22 June: 24.6 µg/m³ Hammond, 23 June: 26.8 µg/m³, 3.0× its usual 8.9 Hammond, 24 June: 17.7 µg/m³ Hammond, 25 June: 10.4 µg/m³ Hammond, 26 June: 31.6 µg/m³ Calumet City Calumet City, 19 June: 25.6 µg/m³ Calumet City, 20 June: 21.6 µg/m³ Calumet City, 21 June: 22.9 µg/m³ Calumet City, 22 June: 22.5 µg/m³ Calumet City, 23 June: 25.8 µg/m³, 3.0× its usual 8.6 Calumet City, 24 June: 18.7 µg/m³ Calumet City, 25 June: 10.8 µg/m³ Calumet City, 26 June: 32.6 µg/m³ 19 Jun 20 21 22 23 24 25 26 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
Appleton Wisconsin, United States 2 23 June 6.8 7.5× Green Bay Wisconsin, United States 2 23 June 7.2 7.1× Madison Wisconsin, United States 1 23 June 6.9 5.7× Waukesha Wisconsin, United States 2 23 June 7.8 5.3× Rockford Illinois, United States 1 23 June 8.0 5.1× Bloomington Illinois, United States 1 23 June 7.9 4.9× South Milwaukee Wisconsin, United States 2 23 June 7.1 4.7× Zion Illinois, United States 1 23 June 6.4 4.5× Milwaukee Wisconsin, United States 2 23 June 8.4 4.3× East Chicago Indiana, United States 1 23 June 7.5 3.8× Joliet Illinois, United States 1 23 June 9.1 3.6× Clinton Iowa, United States 1 23 June 7.7 3.6× Naperville Illinois, United States 1 23 June 9.4 3.4× Des Plaines Illinois, United States 1 23 June 8.4 3.4× Northbrook Illinois, United States 1 23 June 8.4 3.4× Cary Illinois, United States 1 23 June 8.4 3.4× Hammond Indiana, United States 1 23 June 8.9 3.0× Calumet City Illinois, United States 1 23 June 8.6 3.0×
Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.
Against other episodes in the United States
Number 61 of 130 episodes in the United States since our records began, by cities reached.
Eastern United States and Canada, 25 June to 2 July 2023 280 North-eastern United States and Canada, July 2026 264 Eastern United States and Canada, May and June 2023 261 North-eastern United States and Canada, 30 July to 9 August 2025 241 Eastern United States and Canada, July 2023 240 North-eastern United States and Canada, 3 to 9 June 2025 196 Eastern United States and Canada, 14 to 19 June 2023 161 North-eastern United States and Canada, 12 to 16 July 2025 119 North-western United States and Canada, August 2023 110 North-eastern United States and Canada, 10 to 14 June 2025 104 North-western United States and Canada, 4 to 11 August 2026 99 North-eastern United States and Canada, 14 to 19 February 2026 96 North-eastern United States, June 2023 18 Bars: cities reached; colour: the level of the episode's highest daily reading. All 130 .
Use this page SmogRank, North-eastern United States, June 2023: 18 cities with PM2.5 at twice their usual or more, 22 to 23 June 2023, smogrank.com/episodes/2023-06-north-eastern-united-states (accessed 4 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.
