SmogRank / Episodes / United States
North-eastern United States, 21 to 22 July 2025
For 2 days, from 21 to 22 July 2025, 32 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Des Plaines, Illinois, United States: 39.6 µg/m³ on 21 July, about 4.0× its usual 10.0.
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 2 21 to 22 July 2025
Worst day 21 July 26 cities counted
Furthest above usual 4.0× Des Plaines
Day by day
Play 21 July 26 cities at twice their usual or more
Calumet City Hammond East Chicago Gary Portage Waukesha Oconomowoc Michigan City Bloomington Champaign South Bend Peoria Lafayette Clinton Elkhart Decatur Appleton Moline Kokomo Davenport Green Bay Terre Haute Springfield Fishers Muscatine Anderson Fort Wayne Bloomington Muncie Iowa City Cedar Rapids Columbus Upper Alton Lansing Jasper Granite City East Saint Louis St. Louis University City Lemay Arnold Lima Waterloo New Albany Jeffersonville Louisville Ann Arbor Saint Matthews White Oak Dayton Ypsilanti Bay City Toledo Cincinnati Norwood Mason Lebanon Fort Thomas Springfield Redford Taylor Southfield Lincoln Park Dearborn Detroit Windsor Columbia Eastpointe Dublin Ankeny Des Moines Columbus Westerville Gahanna Port Huron Apple Valley Sarnia Burnsville Chatham Shakopee Mankato Saint Michael Ashland Huntington Dolton Wyoming Middletown Bridgeview Rochester Aurora Naperville Portsmouth Minneapolis Oak Lawn Joliet Indianapolis Saint Paul Milwaukee Elgin Kalamazoo Brookfield Chicago Jenison Blaine Holland Grand Rapids Elmwood Park South Milwaukee Northbrook Franklin Park Cary Madison Rockford Eau Claire Zion Des Plaines 18 Jul 19 20 21 22 23 24 25 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
Des Plaines Des Plaines, 18 July: 5.9 µg/m³ Des Plaines, 19 July: 8.1 µg/m³ Des Plaines, 20 July: 9.3 µg/m³ Des Plaines, 21 July: 39.6 µg/m³, 4.0× its usual 10.0 Des Plaines, 22 July: 25.0 µg/m³, 2.6× its usual 9.8 Des Plaines, 23 July: 18.9 µg/m³ Des Plaines, 24 July: 11.6 µg/m³ Des Plaines, 25 July: 7.7 µg/m³ Rockford Rockford, 18 July: 3.9 µg/m³ Rockford, 19 July: 4.4 µg/m³ Rockford, 20 July: 6.4 µg/m³ Rockford, 21 July: 38.9 µg/m³, 3.7× its usual 10.6 Rockford, 22 July: 22.3 µg/m³ Rockford, 23 July: 18.1 µg/m³ Rockford, 24 July: 7.0 µg/m³ Rockford, 25 July: 4.5 µg/m³ Franklin Park Franklin Park, 18 July: 7.6 µg/m³ Franklin Park, 19 July: 7.5 µg/m³ Franklin Park, 20 July: 8.8 µg/m³ Franklin Park, 21 July: 38.6 µg/m³, 3.3× its usual 11.8 Franklin Park, 22 July: 29.0 µg/m³, 2.5× its usual 11.8 Franklin Park, 23 July: 20.0 µg/m³ Franklin Park, 24 July: 12.6 µg/m³ Franklin Park, 25 July: 6.7 µg/m³ Elmwood Park Elmwood Park, 18 July: 6.0 µg/m³ Elmwood Park, 19 July: 7.4 µg/m³ Elmwood Park, 20 July: 8.4 µg/m³ Elmwood Park, 21 July: 35.2 µg/m³, 3.0× its usual 11.8 Elmwood Park, 22 July: 26.8 µg/m³, 2.3× its usual 11.8 Elmwood Park, 23 July: 18.8 µg/m³ Elmwood Park, 24 July: 10.7 µg/m³ Elmwood Park, 25 July: 5.8 µg/m³ Elgin Elgin, 18 July: 4.5 µg/m³ Elgin, 19 July: 5.2 µg/m³ Elgin, 20 July: 6.1 µg/m³ Elgin, 21 July: 35.0 µg/m³, 2.7× its usual 13.1 Elgin, 22 July: 24.2 µg/m³ Elgin, 23 July: 17.2 µg/m³ Elgin, 24 July: 9.5 µg/m³ Elgin, 25 July: 4.5 µg/m³ Cary Cary, 18 July: 4.4 µg/m³ Cary, 19 July: 6.0 µg/m³ Cary, 20 July: 7.0 µg/m³ Cary, 21 July: 34.9 µg/m³, 3.6× its usual 9.6 Cary, 22 July: 21.3 µg/m³ Cary, 23 July: 17.1 µg/m³ Cary, 24 July: 9.8 µg/m³ Cary, 25 July: 4.8 µg/m³ Eau Claire Eau Claire, 18 July: 3.6 µg/m³ Eau Claire, 19 July: 5.0 µg/m³ Eau Claire, 20 July: 12.6 µg/m³ Eau Claire, 21 July: 33.4 µg/m³, 3.8× its usual 8.9 Eau Claire, 22 July: 12.3 µg/m³ Eau Claire, 23 July: 6.9 µg/m³ Eau Claire, 24 July: 5.2 µg/m³ Eau Claire, 25 July: 44.4 µg/m³ Kalamazoo Kalamazoo, 18 July: 4.1 µg/m³ Kalamazoo, 19 July: 5.6 µg/m³ Kalamazoo, 20 July: 5.5 µg/m³ Kalamazoo, 21 July: 33.4 µg/m³, 2.8× its usual 11.8 Kalamazoo, 22 July: 14.4 µg/m³ Kalamazoo, 23 July: 11.7 µg/m³ Kalamazoo, 24 July: 11.3 µg/m³ Kalamazoo, 25 July: 5.3 µg/m³ Northbrook Northbrook, 18 July: 3.0 µg/m³ Northbrook, 19 July: 5.1 µg/m³ Northbrook, 20 July: 7.6 µg/m³ Northbrook, 21 July: 32.1 µg/m³, 3.1× its usual 10.2 Northbrook, 22 July: 18.4 µg/m³ Northbrook, 23 July: 12.0 µg/m³ Northbrook, 24 July: 5.5 µg/m³ Northbrook, 25 July: 6.7 µg/m³ Madison Madison, 18 July: 4.0 µg/m³ Madison, 19 July: 4.6 µg/m³ Madison, 20 July: 8.8 µg/m³ Madison, 21 July: 31.1 µg/m³, 3.7× its usual 8.4 Madison, 22 July: 15.7 µg/m³ Madison, 23 July: 13.5 µg/m³ Madison, 24 July: 3.8 µg/m³ Madison, 25 July: 10.8 µg/m³ Grand Rapids Grand Rapids, 18 July: 4.1 µg/m³ Grand Rapids, 19 July: 6.3 µg/m³ Grand Rapids, 20 July: 12.2 µg/m³ Grand Rapids, 21 July: 30.8 µg/m³, 3.0× its usual 10.4 Grand Rapids, 22 July: 10.9 µg/m³ Grand Rapids, 23 July: 12.6 µg/m³ Grand Rapids, 24 July: 11.3 µg/m³ Grand Rapids, 25 July: 6.6 µg/m³ Zion Zion, 18 July: 3.4 µg/m³ Zion, 19 July: 6.3 µg/m³ Zion, 20 July: 9.2 µg/m³ Zion, 21 July: 30.6 µg/m³, 3.9× its usual 7.8 Zion, 22 July: 16.1 µg/m³ Zion, 23 July: 14.1 µg/m³ Zion, 24 July: 8.0 µg/m³ Zion, 25 July: 10.5 µg/m³ Jenison Jenison, 18 July: 4.3 µg/m³ Jenison, 19 July: 5.9 µg/m³ Jenison, 20 July: 8.1 µg/m³ Jenison, 21 July: 30.0 µg/m³, 2.9× its usual 10.2 Jenison, 22 July: 10.5 µg/m³ Jenison, 23 July: 11.9 µg/m³ Jenison, 24 July: 10.0 µg/m³ Jenison, 25 July: 5.3 µg/m³ Bridgeview Bridgeview, 18 July: 9.0 µg/m³ Bridgeview, 19 July: 6.0 µg/m³ Bridgeview, 20 July: 8.2 µg/m³ Bridgeview, 21 July: 30.0 µg/m³, 2.2× its usual 13.4 Bridgeview, 22 July: 28.2 µg/m³, 2.1× its usual 13.4 Bridgeview, 23 July: 17.9 µg/m³ Bridgeview, 24 July: 11.0 µg/m³ Bridgeview, 25 July: 8.4 µg/m³ Holland Holland, 18 July: 5.8 µg/m³ Holland, 19 July: 7.9 µg/m³ Holland, 20 July: 8.6 µg/m³ Holland, 21 July: 29.8 µg/m³, 3.0× its usual 10.1 Holland, 22 July: 14.5 µg/m³ Holland, 23 July: 14.3 µg/m³ Holland, 24 July: 14.6 µg/m³ Holland, 25 July: 8.3 µg/m³ Chicago Chicago, 18 July: 6.4 µg/m³ Chicago, 19 July: 6.4 µg/m³ Chicago, 20 July: 8.1 µg/m³ Chicago, 21 July: 29.4 µg/m³, 2.9× its usual 10.1 Chicago, 22 July: 27.4 µg/m³, 2.7× its usual 10.1 Chicago, 23 July: 17.6 µg/m³ Chicago, 24 July: 10.6 µg/m³ Chicago, 25 July: 6.3 µg/m³ Brookfield Brookfield, 18 July: 7.1 µg/m³ Brookfield, 19 July: 5.3 µg/m³ Brookfield, 20 July: 6.4 µg/m³ Brookfield, 21 July: 28.7 µg/m³, 2.9× its usual 9.9 Brookfield, 22 July: 28.1 µg/m³, 2.9× its usual 9.8 Brookfield, 23 July: 16.8 µg/m³ Brookfield, 24 July: 10.8 µg/m³ Brookfield, 25 July: 6.5 µg/m³ Naperville Naperville, 18 July: 3.8 µg/m³ Naperville, 19 July: 5.6 µg/m³ Naperville, 20 July: 6.4 µg/m³ Naperville, 21 July: 27.9 µg/m³, 2.4× its usual 11.5 Naperville, 22 July: 26.7 µg/m³, 2.3× its usual 11.4 Naperville, 23 July: 17.3 µg/m³ Naperville, 24 July: 8.9 µg/m³ Naperville, 25 July: 6.5 µg/m³ Wyoming Wyoming, 18 July: 7.6 µg/m³ Wyoming, 19 July: 9.3 µg/m³ Wyoming, 20 July: 11.7 µg/m³ Wyoming, 21 July: 27.5 µg/m³, 2.1× its usual 13.1 Wyoming, 22 July: 12.5 µg/m³ Wyoming, 23 July: 14.8 µg/m³ Wyoming, 24 July: 16.1 µg/m³ Wyoming, 25 July: 10.2 µg/m³ Milwaukee Milwaukee, 18 July: 4.9 µg/m³ Milwaukee, 19 July: 7.1 µg/m³ Milwaukee, 20 July: 15.5 µg/m³ Milwaukee, 21 July: 26.9 µg/m³, 2.6× its usual 10.2 Milwaukee, 22 July: 20.2 µg/m³ Milwaukee, 23 July: 16.2 µg/m³ Milwaukee, 24 July: 6.9 µg/m³ Milwaukee, 25 July: 20.7 µg/m³ South Milwaukee South Milwaukee, 18 July: 4.1 µg/m³ South Milwaukee, 19 July: 5.6 µg/m³ South Milwaukee, 20 July: 10.4 µg/m³ South Milwaukee, 21 July: 26.5 µg/m³, 3.1× its usual 8.5 South Milwaukee, 22 July: 18.1 µg/m³ South Milwaukee, 23 July: 14.9 µg/m³ South Milwaukee, 24 July: 6.6 µg/m³ South Milwaukee, 25 July: 17.6 µg/m³ Saint Paul Saint Paul, 18 July: 4.3 µg/m³ Saint Paul, 19 July: 6.3 µg/m³ Saint Paul, 20 July: 7.8 µg/m³ Saint Paul, 21 July: 26.2 µg/m³, 2.6× its usual 10.1 Saint Paul, 22 July: 11.2 µg/m³ Saint Paul, 23 July: 6.6 µg/m³ Saint Paul, 24 July: 13.8 µg/m³ Saint Paul, 25 July: 47.7 µg/m³ Minneapolis Minneapolis, 18 July: 6.0 µg/m³ Minneapolis, 19 July: 7.0 µg/m³ Minneapolis, 20 July: 8.1 µg/m³ Minneapolis, 21 July: 25.6 µg/m³, 2.5× its usual 10.1 Minneapolis, 22 July: 13.1 µg/m³ Minneapolis, 23 July: 7.4 µg/m³ Minneapolis, 24 July: 15.8 µg/m³ Minneapolis, 25 July: 49.3 µg/m³ Blaine Blaine, 18 July: 4.7 µg/m³ Blaine, 19 July: 5.3 µg/m³ Blaine, 20 July: 9.4 µg/m³ Blaine, 21 July: 25.5 µg/m³, 3.0× its usual 8.4 Blaine, 22 July: 10.4 µg/m³ Blaine, 23 July: 6.1 µg/m³ Blaine, 24 July: 16.6 µg/m³ Blaine, 25 July: 47.3 µg/m³ Aurora Aurora, 18 July: 3.9 µg/m³ Aurora, 19 July: 5.0 µg/m³ Aurora, 20 July: 5.0 µg/m³ Aurora, 21 July: 25.3 µg/m³, 2.3× its usual 10.8 Aurora, 22 July: 26.2 µg/m³, 2.4× its usual 10.8 Aurora, 23 July: 16.2 µg/m³ Aurora, 24 July: 8.4 µg/m³ Aurora, 25 July: 5.4 µg/m³ Rochester Rochester, 18 July: 6.4 µg/m³ Rochester, 19 July: 7.1 µg/m³ Rochester, 20 July: 6.3 µg/m³ Rochester, 21 July: 25.0 µg/m³, 2.4× its usual 10.6 Rochester, 22 July: 9.9 µg/m³ Rochester, 23 July: 7.0 µg/m³ Rochester, 24 July: 3.8 µg/m³ Rochester, 25 July: 14.1 µg/m³ Indianapolis Indianapolis, 18 July: 5.5 µg/m³ Indianapolis, 19 July: 6.7 µg/m³ Indianapolis, 20 July: 6.5 µg/m³ Indianapolis, 21 July: 9.7 µg/m³ Indianapolis, 22 July: 27.9 µg/m³, 2.5× its usual 11.2 Indianapolis, 23 July: 17.6 µg/m³ Indianapolis, 24 July: 14.7 µg/m³ Indianapolis, 25 July: 12.1 µg/m³ Joliet Joliet, 18 July: 4.8 µg/m³ Joliet, 19 July: 5.2 µg/m³ Joliet, 20 July: 5.5 µg/m³ Joliet, 21 July: 20.5 µg/m³ Joliet, 22 July: 27.5 µg/m³, 2.5× its usual 11.0 Joliet, 23 July: 17.2 µg/m³ Joliet, 24 July: 9.5 µg/m³ Joliet, 25 July: 5.1 µg/m³ Dolton Dolton, 18 July: 7.9 µg/m³ Dolton, 19 July: 7.0 µg/m³ Dolton, 20 July: 6.6 µg/m³ Dolton, 21 July: 22.1 µg/m³ Dolton, 22 July: 26.9 µg/m³, 2.1× its usual 12.9 Dolton, 23 July: 17.5 µg/m³ Dolton, 24 July: 12.0 µg/m³ Dolton, 25 July: 6.2 µg/m³ Middletown Middletown, 18 July: no reading Middletown, 19 July: no reading Middletown, 20 July: no reading Middletown, 21 July: 16.1 µg/m³ Middletown, 22 July: 26.2 µg/m³, 2.2× its usual 11.9 Middletown, 23 July: no reading Middletown, 24 July: no reading Middletown, 25 July: no reading Oak Lawn Oak Lawn, 18 July: 6.1 µg/m³ Oak Lawn, 19 July: 5.4 µg/m³ Oak Lawn, 20 July: 6.4 µg/m³ Oak Lawn, 21 July: 24.3 µg/m³ Oak Lawn, 22 July: 25.7 µg/m³, 2.5× its usual 10.3 Oak Lawn, 23 July: 16.0 µg/m³ Oak Lawn, 24 July: 9.4 µg/m³ Oak Lawn, 25 July: 5.3 µg/m³ Portsmouth Portsmouth, 18 July: 6.9 µg/m³ Portsmouth, 19 July: 7.1 µg/m³ Portsmouth, 20 July: 7.4 µg/m³ Portsmouth, 21 July: 10.9 µg/m³ Portsmouth, 22 July: 25.0 µg/m³, 2.5× its usual 9.9 Portsmouth, 23 July: 18.0 µg/m³ Portsmouth, 24 July: 15.1 µg/m³ Portsmouth, 25 July: 14.5 µg/m³ 18 Jul 19 20 21 22 23 24 25 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
Des Plaines Illinois, United States 2 21 July 10.0 4.0× Zion Illinois, United States 1 21 July 7.8 3.9× Eau Claire Wisconsin, United States 1 21 July 8.9 3.8× Rockford Illinois, United States 1 21 July 10.6 3.7× Madison Wisconsin, United States 1 21 July 8.4 3.7× Cary Illinois, United States 1 21 July 9.6 3.6× Franklin Park Illinois, United States 2 21 July 11.8 3.3× Northbrook Illinois, United States 1 21 July 10.2 3.1× South Milwaukee Wisconsin, United States 1 21 July 8.5 3.1× Elmwood Park Illinois, United States 2 21 July 11.8 3.0× Grand Rapids Michigan, United States 1 21 July 10.4 3.0× Holland Michigan, United States 1 21 July 10.1 3.0× Blaine Minnesota, United States 1 21 July 8.4 3.0× Jenison Michigan, United States 1 21 July 10.2 2.9× Chicago Illinois, United States 2 21 July 10.1 2.9× Brookfield Illinois, United States 2 21 July 9.9 2.9× Kalamazoo Michigan, United States 1 21 July 11.8 2.8× Elgin Illinois, United States 1 21 July 13.1 2.7× Milwaukee Wisconsin, United States 1 21 July 10.2 2.6× Saint Paul Minnesota, United States 1 21 July 10.1 2.6× Indianapolis Indiana, United States 1 22 July 11.2 2.5× Joliet Illinois, United States 1 22 July 11.0 2.5× Oak Lawn Illinois, United States 1 22 July 10.3 2.5× Minneapolis Minnesota, United States 1 21 July 10.1 2.5× Portsmouth Ohio, United States 1 22 July 9.9 2.5× Naperville Illinois, United States 2 21 July 11.5 2.4× Aurora Illinois, United States 2 22 July 10.8 2.4× Rochester Minnesota, United States 1 21 July 10.6 2.4× Bridgeview Illinois, United States 2 21 July 13.4 2.2× Middletown Ohio, United States 1 22 July 11.9 2.2× Wyoming Michigan, United States 1 21 July 13.1 2.1× Dolton Illinois, United States 1 22 July 12.9 2.1×
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 27 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, 21 to 22 July 2025 32 Bars: cities reached; colour: the level of the episode's highest daily reading. All 130 .
Use this page SmogRank, North-eastern United States, 21 to 22 July 2025: 32 cities with PM2.5 at twice their usual or more, 21 to 22 July 2025, smogrank.com/episodes/2025-07-21-north-eastern-united-states (accessed 4 October 2026).
Copy citation Download top 10 (PNG)
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.
