What was the worst air-quality day in El Paso?

April 1, 2025, when daily PM2.5 reached 288.5 µg/m³ (AQI 426), about 13.1 cigarette-equivalents. It ranks first of 7,232 monitored days since 1999.

What is the highest AQI recorded in El Paso?

On the worst day, the daily PM2.5 AQI reached 426 (Hazardous). EPA's official metro AQI, which uses the single worst monitor of any pollutant, peaked at 2122 on March 18, 2025.

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 El Paso get air this bad?

Rarely. The record sits at the far end of 7,232 measured days; El Paso averages 1 "unhealthy" day a year.

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

El Paso's worst air quality days

#7 of 100 US metros by worst day · El Paso, TX metro area

Based on the available regulatory-monitor record since 1999, April 1, 2025 ranks as El Paso's most severe daily PM2.5 day: 288.5 µg/m³ (AQI 426, hazardous), about 13.1 cigarettes in a day.

Daily rank: #1
Period of record: Since 1999
Peak daily PM2.5: 288.5 µg/m³
About: 13.1 cigarettes
Latest event: 1 day, May 2025
Status: Finalized

Current conditions on the smoke map → Data through Mar 31, 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 11 EPA monitors in the El Paso, TX metro area (CBSA). Days after March 31, 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 2122 on March 18, 2025 (defining pollutant PM10, above the scale's usual 500 cap).

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.

Latest major event May 2025 One ranked day, May 14, 2025, peaking at 78.5 µg/m³, #14 all-time. See where it ranks ↓

What were El Paso's worst days?

Rank	Date	Daily PM2.5
#1	April 1, 2025	288.5 µg/m³
#2	March 18, 2025	285.8 µg/m³
#3	March 3, 20253-day stretch	238.6 µg/m³
#4	April 27, 2025	164.3 µg/m³
#5	March 18, 2012	130.4 µg/m³
#6	March 6, 2025	127.3 µg/m³
#7	March 4, 2025	126.3 µg/m³
#8	April 17, 20252-day stretch	107.2 µg/m³
#9	April 18, 2025	103.3 µg/m³
#10	February 11, 2025	94.2 µg/m³
#11	March 7, 2012	85 µg/m³
#12	April 10, 2001	82.9 µg/m³
#13	April 17, 2013	78.6 µg/m³
#14	May 14, 2025	78.5 µg/m³
#15	April 9, 2013	75.5 µg/m³

What caused El Paso's worst days?

The event catalog has named 11 episodes affecting El Paso, 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.

Dust 2025-05-13 dust episode affecting El Paso, TX May 14, 2025 · 78.5 µg/m³ here , #14 all-time
Dust March 18, 2025 El Paso Borderland sand-and-dust storm Mar 18, 2025 · 285.8 µg/m³ here , #2 all-time · from El Paso Borderland
Dust 2025-03-13 dust episode affecting El Paso, TX Mar 13, 2025 · 60.5 µg/m³ here , #22 all-time
Dust 2025-03-03 dust episode affecting El Paso, TX Mar 3, 2025 · 238.6 µg/m³ here , #3 all-time
Dust 2025-02-27 dust episode affecting El Paso, TX Feb 27, 2025 · 59.2 µg/m³ here , #25 all-time
Dust 2025-02-14 dust episode affecting El Paso, TX Feb 14, 2025 · 63.3 µg/m³ here , #19 all-time

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

How does it compare?

The record is 1% higher than the next-worst day: 288.5 µg/m³ (April 1, 2025) against 285.8 µg/m³ (March 18, 2025).

How unusual is air like this?

30× a typical day here, at the record

1 day a year, on average, at "unhealthy" or worse

0 µg/m³289 µg/m³

Every measured day near El Paso, by daily PM2.5; the record stands far out on the right. 110 days at "unhealthy for sensitive groups" or worse, 28 at "unhealthy", 7 at "very unhealthy" (2024 EPA thresholds, across 7,232 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 El Paso?: April 1, 2025, when daily PM2.5 reached 288.5 µg/m³ (AQI 426), about 13.1 cigarette-equivalents. It ranks first of 7,232 monitored days since 1999.
What is the highest AQI recorded in El Paso?: On the worst day, the daily PM2.5 AQI reached 426 (Hazardous). EPA's official metro AQI, which uses the single worst monitor of any pollutant, peaked at 2122 on March 18, 2025.
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 El Paso get air this bad?: Rarely. The record sits at the far end of 7,232 measured days; El Paso averages 1 "unhealthy" day a year.
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: el-paso.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: El Paso, TX. iaqng.com/records/el-paso. Data: U.S. EPA AQS and AirNow. Accessed July 26, 2026.