SmogRank / United States / Illinois / Blue Island

Blue Island, month by month

Blue Island has a measured daily mean on 126 days since 31 January 2026. Its worst month was March 2026, at 54 US AQI (10.7 µg/m³), 1,483rd of 2,971 cities on that month's world ranking. Its cleanest was September 2026, at 47 US AQI (8.4 µg/m³).

Every month since 2026

2026too few days for a mean (a year needs 199)126 days measured
Jan1 dayFeb18 daysMar54#1,483Apr2 daysMay9 daysJun7 daysJul12 daysAug16 daysSep47#911Oct38#1,442
Each square is a month's mean PM2.5 in US AQI from Blue Island's measured days, with its place on that month's world ranking under it. A month has a mean once 70% of its days are measured, the rule the monthly rankings use; under that, the square gives the days measured. Each square opens that month's ranking with Blue Island marked; each year, the year's. A dashed square is the running month, so far.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

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

Months without a mean, and why

7 months
MonthWhy
Aug 202616 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Jul 202612 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Jun 20267 of 30 days measured; a month needs 21. The others: 23 with under 18 hours of readings or readings that failed our checks.
May 20269 of 31 days measured; a month needs 22. The others: 22 with under 18 hours of readings or readings that failed our checks.
Apr 20262 of 30 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks.
Feb 202618 of 28 days measured; a month needs 20. The others: 10 with under 18 hours of readings or readings that failed our checks.
Jan 20261 of 31 days measured; a month needs 22.

A day counts once 18 hours of it are measured; a month needs 70% of its days.

Blue Island's worst months

MonthUS AQIDays measuredWorld rankEpisode
March 2026 5410.7 µg/m³24 of 311,483rdof 2,971North-eastern United States and Canada, March 2026
September 2026 478.4 µg/m³27 of 30911thof 2,997–

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.

Blue Island's worst days

DayUS AQIEpisode
16 Jul 2026 242166.5 µg/m³–
4 Jul 2026 12645.6 µg/m³–
15 Feb 2026 8426.9 µg/m³–
4 Mar 2026 8426.9 µg/m³North-eastern United States and Canada, March 2026
18 Jul 2026 7421.3 µg/m³–
19 Mar 2026 7321.1 µg/m³–
5 Jul 2026 7320.8 µg/m³–
3 Mar 2026 7320.7 µg/m³–
2 Feb 2026 7220.2 µg/m³–
13 Jul 2026 7019.5 µg/m³–

Daily means, the highest since 31 Jan 2026; 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, Blue Island, United States, 31 Jan 2026 – 11 Oct 2026. Monitor data from Clarity via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/us/blue-island/history (accessed 13 Oct 2026).

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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.

Blue Island now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-13 01:07 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).