What was the worst air-quality day in Colorado Springs?

May 20, 2023, when daily PM2.5 reached 60.1 µg/m³ (AQI 154), about 2.7 cigarette-equivalents. It ranks first of 5,651 monitored days since 1999.

What is the highest AQI recorded in Colorado Springs?

On the worst day, the daily PM2.5 AQI reached 154 (Unhealthy). EPA's official metro AQI, which uses the single worst monitor of any pollutant, peaked at 166 on July 24, 2024.

Were these days caused by wildfire smoke?

This page ranks measured PM2.5 without assigning a cause: a high day can be smoke, fireworks, dust, an inversion, or industry. A separate wildfire-smoke event ranking, using a published attribution method with its version disclosed, is the next layer of this catalog.

How often does Colorado Springs get air this bad?

Rarely. The record sits at the far end of 5,651 measured days; Colorado Springs averages about one "unhealthy" day every 28 years.

Why did different apps show different numbers that day?

Concentration (µg/m³) and AQI are different scales; hourly, NowCast, and daily values answer different questions; a single monitor differs from a citywide composite; and live feeds get revised when EPA certifies data. This page uses the certified daily record, with the provisional tail labeled.

← All 100 US metros ranked

Historical PM2.5 records

Colorado Springs's worst air quality days

#92 of 100 US metros by worst day · Colorado Springs, CO metro area

Based on the available regulatory-monitor record since 1999, May 20, 2023 ranks as Colorado Springs's most severe daily PM2.5 day: 60.1 µg/m³ (AQI 154, unhealthy), about 2.7 cigarettes in a day.

Daily rank: #1
Period of record: Since 1999
Peak daily PM2.5: 60.1 µg/m³
About: 2.7 cigarettes
Status: Finalized

Current conditions on the smoke map → Data through Apr 30, 2026 · page built July 26, 2026

Show

The worst-hit part of the metro: its highest credible monitor each day.

How this is measured sources, the daily measure, and what this ranking is not

Source. Daily PM2.5 from the U.S. EPA Air Quality System (AQS) , back to 1999, across 3 EPA monitors in the Colorado Springs, CO metro area (CBSA). Days after April 30, 2026 are preliminary AirNow readings, marked provisional, and re-rank once EPA certifies them (usually the following spring).

The daily measure. "Worst area" is the metro's highest credible monitor each day, with lone bad-monitor spikes dropped (the raw single-monitor max before that filter is in the data but not charted). "Metro average" averages every monitor. The unit choice re-reads the same value as µg/m³, cigarette-equivalents (PM2.5 ÷ 22, Berkeley Earth, an illustration rather than a medical reading), or the EPA 2024 PM2.5 AQI.

Official AQI. EPA's reported metro AQI uses the single worst monitor of any pollutant, so it can run higher than the values here. The highest official daily AQI among the ranked days is 166 on July 24, 2024 (defining pollutant Ozone).

What this ranking is not. It does not attribute days to wildfire smoke: a high-PM2.5 day can be dust, fireworks, an inversion, or industry. The wildfire-smoke event ranking below arrives with a published attribution method.

Colorado Springs's monitoring record is thinner than most, 5,651 days since 1999, with gaps between them. The ranking is real, but treat it as indicative rather than a complete accounting.

What were Colorado Springs's worst days?

Rank	Date	Daily PM2.5
#1	May 20, 20232-day stretch	60.1 µg/m³
#2	May 19, 2023	53.2 µg/m³
#3	August 8, 20212-day stretch	44.6 µg/m³
#4	September 4, 2017	41.6 µg/m³
#5	August 21, 20182-day stretch	35.6 µg/m³
#6	August 7, 2021	32.1 µg/m³
#7	June 1, 2001	31.7 µg/m³
#8	December 3, 2003	30.8 µg/m³
#9	January 22, 2008	30.4 µg/m³
#10	August 22, 2018	30 µg/m³
#11	July 23, 2024	29.7 µg/m³
#12	September 17, 2020	29.5 µg/m³
#13	August 1, 2021	29 µg/m³
#14	August 22, 2020	28.7 µg/m³
#15	March 7, 2019	28.4 µg/m³

What caused Colorado Springs's worst days?

The event catalog has named 12 episodes affecting Colorado Springs, each resolved to a cause only where retained evidence supports it: EPA monitor qualifiers, NWS alerts, agency statements, and reporting. The ranking above stays cause-neutral; this is where the causes live.

Wildfire smoke 2026-07-03 wildfire smoke episode affecting Colorado Springs, CO Jul 3, 2026 · 25.8 µg/m³ here , #24 all-time
Wildfire smoke 2024-07-23 Colorado Springs, CO wildfire smoke episode Jul 23, 2024 · 29.7 µg/m³ here , #11 all-time · from Canada
Wildfire smoke 2023 mid-May Canadian wildfire-smoke episode May 20, 2023 · 60.1 µg/m³ here , #1 all-time · from Canada
Mixed causes 2022-05-09 Colorado Springs, CO wildfire smoke and dust episode May 9, 2022 · 27.3 µg/m³ here , #18 all-time · from Four Corners
Wildfire smoke 2021-08-07 2-area wildfire-smoke episode Aug 8, 2021 · 44.6 µg/m³ here , #3 all-time · from Colorado Springs, CO
Wildfire smoke 2021-08-01 Colorado Springs wildfire-smoke episode Aug 1, 2021 · 29 µg/m³ here , #13 all-time · from Colorado Springs, CO

6 more, plus every named episode and its evidence is in the event catalog.

How does it compare?

The record is 13% higher than the next-worst day: 60.1 µg/m³ (May 20, 2023) against 53.2 µg/m³ (May 19, 2023).

How unusual is air like this?

11× a typical day here, at the record

1 in 28 years, roughly, sees an "unhealthy" day here

0 µg/m³60 µg/m³

Every measured day near Colorado Springs, by daily PM2.5; the record stands far out on the right. 5 days at "unhealthy for sensitive groups" or worse, 1 at "unhealthy", 0 at "very unhealthy" (2024 EPA thresholds, across 5,651 measured days).

Year by year (1999–2026)

Worst single day each year, by the selected measure.

Why did reported numbers differ?

During a major event, AirNow, weather apps, news reports, and neighborhood monitors can all show different figures at the same moment. All of them can be right:

Concentration vs AQI. µg/m³ is the measurement; AQI is a 0 to 500 index derived from it. "330 µg/m³" and "AQI 500" can describe the same air.
Hourly vs NowCast vs daily. An hourly peak, the NowCast rolling estimate apps display, and the full-day average answer different questions; this page ranks full days.
One monitor vs a composite. A single sensor can read far above or below a citywide figure. The measure toggle above shows both framings.
Live vs certified. Real-time feeds get corrected when EPA certifies data months later, which is why recent days here carry a provisional label.

What about indoors?

Citywide monitors can tell you what happened outside. They cannot tell you what happened inside a particular home, school, or facility: filtration, ventilation, and building operation decide that. During and after days like the ones above, outdoor particles become an indoor load question.

Check current conditions and the next clean-air window → Estimate recent filter load where you are →

Common questions

What was the worst air-quality day in Colorado Springs?: May 20, 2023, when daily PM2.5 reached 60.1 µg/m³ (AQI 154), about 2.7 cigarette-equivalents. It ranks first of 5,651 monitored days since 1999.
What is the highest AQI recorded in Colorado Springs?: On the worst day, the daily PM2.5 AQI reached 154 (Unhealthy). EPA's official metro AQI, which uses the single worst monitor of any pollutant, peaked at 166 on July 24, 2024.
Were these days caused by wildfire smoke?: This page ranks measured PM2.5 without assigning a cause: a high day can be smoke, fireworks, dust, an inversion, or industry. A separate wildfire-smoke event ranking, using a published attribution method with its version disclosed, is the next layer of this catalog.
How often does Colorado Springs get air this bad?: Rarely. The record sits at the far end of 5,651 measured days; Colorado Springs averages about one "unhealthy" day every 28 years.
Why did different apps show different numbers that day?: Concentration (µg/m³) and AQI are different scales; hourly, NowCast, and daily values answer different questions; a single monitor differs from a citywide composite; and live feeds get revised when EPA certifies data. This page uses the certified daily record, with the provisional tail labeled.

Data and citation

Ranked days for both measures are downloadable, with units and status flags: colorado-springs.csv. Source: U.S. EPA Air Quality System (AQS) daily PM2.5, with preliminary AirNow readings for the uncertified tail. Cite as:

IAQng Air Records: Colorado Springs, CO. iaqng.com/records/colorado-springs. Data: U.S. EPA AQS and AirNow. Accessed July 26, 2026.