SmogRank / United States / Illinois / Northbrook
Northbrook, month by month
Northbrook has a measured daily mean on 1,364 days since 1 January 2023. Its worst month was July 2026, at 89 US AQI (29.3 µg/m³), 156th of 2,784 cities on that month's world ranking. Its cleanest was May 2026, at 25 US AQI (4.5 µg/m³). 2025 averaged 41 US AQI (7.4 µg/m³), against 41 US AQI (7.3 µg/m³) in 2024.
Every month since 2023
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Northbrook's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2026 | 8929.3 µg/m³ | 156thof 2,784 | Northern United States and Canada, July 2026 North-eastern United States, June and July 2026 |
| June 2023 | 8527.4 µg/m³ | 133rdof 1,603 | Eastern United States and Canada, June and July 2023 North-eastern United States, June 2023and 2 more |
| July 2023 | 6114.4 µg/m³ | 174thof 1,432 | Northern United States and Canada, July 2023 United States and Canada, July 2023and 2 more |
| June 2025 | 5913.6 µg/m³ | 588thof 2,508 | Northern United States and Canada, May and June 2025 |
| August 2023 | 5812.7 µg/m³ | 287thof 1,980 | – |
| July 2025 | 5611.8 µg/m³ | 877thof 2,889 | North-eastern United States and Canada, 29 July to 9 August 2025 Northern United States, July 2025and 1 more |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Northbrook's worst days
| Day | US AQI | Episode |
|---|---|---|
| 16 Jul 2026 | 493322.0 µg/m³ | Northern United States and Canada, July 2026 |
| 17 Jul 2026 | 232157.0 µg/m³ | Northern United States and Canada, July 2026 |
| 28 Jun 2023 | 214139.0 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 27 Jun 2023 | 204129.0 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 29 Jun 2023 | 16473.9 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 31 Jul 2025 | 15560.7 µg/m³ | North-eastern United States and Canada, 29 July to 9 August 2025 |
| 19 Jul 2026 | 14754.2 µg/m³ | Northern United States and Canada, July 2026 |
| 20 Jul 2026 | 13448.9 µg/m³ | Northern United States and Canada, July 2026 |
| 25 Jul 2023 | 13348.5 µg/m³ | Northern United States and Canada, July 2023 |
| 5 Jun 2025 | 12846.6 µg/m³ | Northern United States and Canada, May and June 2025 |
Daily means, the highest since 1 Jan 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Northbrook, United States, 1 Jan 2023 – 11 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/northbrook/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Northbrook now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 17:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).