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Wildfire smoke Possible

2000-09-03 to 2000-09-04 New Orleans-Metairie, LA wildfire-smoke episode

September 3, 2000 to September 4, 2000

Daily PM2.5 peaked at 48.2 µg/m³ near New Orleans across 1 covered metro home to 966,230 people. 1 metro placed a top-ten day in their record.

Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 3.2 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 3.1 million cigarettes. An awareness illustration of outdoor exposure at 22 µg/m³ per cigarette (Berkeley Earth), counting only the event's ranked days; not a medical dose.

Why we think this happened

The basis for “Wildfire smoke”

New Orleans airport reported smoke and haze for four hours on September 4 inside the catalog window. NOAA documents an exceptional Louisiana wildfire outbreak and long smoke plumes on that date, while FPA-FOD independently records a same-day Louisiana wildfire within 50 miles. The combined evidence supports wildfire smoke as possible but does not connect a particular plume to the New Orleans PM2.5 monitor.

Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.

USDA Forest Service Rocky Mountain Research Station hypothesis

FPA-FOD sixth-edition fire-occurrence records near the smoke observation

FPA-FOD records a five-acre Louisiana wildfire 44.6 miles from the New Orleans surface station on September 4. NOAA's TexAQS field-study newsletter independently documents a much larger Louisiana wildfire outbreak on September 4-5, including a 30,000-acre fire south of Alexandria, roughly 50,000 acres burned since August 31, and satellite-observed smoke plumes more than 100 miles long.

NOAA Aeronomy Laboratory TexAQS 2000 Field Study · Sep 11, 2000 hypothesis

Texas/Louisiana wildfires — September 4th and 5th

NOAA's TexAQS field-study newsletter documents the September 4-5 Texas/Louisiana wildfire outbreak. It reports a 30,000-acre fire south of Alexandria, about 50,000 Louisiana acres burned since August 31, satellite-observed smoke plumes over 100 miles long, and Louisiana/Texas marsh fires visible on September 4.

Inference, not direct attribution

surface_smoke_plus_bounded_fire_occurrences_possible.v1: This inference is recorded in the catalog methodology.

See every retained source and limitation ↓

Evidence path

From source to city

A cause is more convincing when the record connects three things: something happened, the air mass moved toward the region, and local instruments responded. Here is how much of that chain is documented for this event.

Open the evidence ledger ↓
  1. 1

    Source or mechanism

    Pattern-based explanation

    surface_smoke_plus_bounded_fire_occurrences_possible.v1. This inference is recorded in the catalog methodology.

    Inferred
  2. 2

    Air-mass movement

    The transport path has not been reconstructed

    The retained record does not yet show how air traveled from the proposed source to these metros. A trajectory replay or dated plume analysis belongs here.

    Research gap
  3. 3

    Local response

    48.2 µg/m³ near New Orleans

    EPA monitors recorded the event across 1 metro. The peak daily concentration is roughly 2.2 cigarette-equivalents at the outdoor daily rate.

    Inspect the pollutant and weather signals ↓
    Documented

Event autopsy

What the instruments saw

Before, during, and after the episode: nearby pollutant monitors and surface-weather stations show what changed. This context tests the “Wildfire smoke” explanation; it does not assign the cause by itself.

Observed context · not attribution

New Orleans-Metairie, LA

Monitor comparison window 2000-08-31 to 2000-09-07 · PM2.5 target: Kenner

6 pollutant signals
Fine-particle pulse 41.6 µg/m³

96% above nearby days

PM10 45 µg/m³

No adjacent-day comparison

Pollution fingerprint

Metro-wide median of reporting monitors
PM2.5 41.6 µg/m³

96% higher than surrounding days

Before20.9 µg/m³ Event41.6 µg/m³ After11.3 µg/m³
5 monitors · 24 HOUR
PM10 45 µg/m³

No adjacent-day comparison

Before— Event45 µg/m³ After—
3 monitors · 24 HOUR
Carbon monoxide 0.475 ppm

About the same as surrounding days

Before0.624 ppm Event0.475 ppm After0.300 ppm
2 monitors · 1 HOUR
Nitrogen dioxide 13.1 ppb

11% lower than surrounding days

Before19.2 ppb Event13.1 ppb After11.1 ppb
2 monitors · 1 HOUR
Sulfur dioxide 0.188 ppb

33% lower than surrounding days

Before1.29 ppb Event0.188 ppb After0.083 ppb
1 monitor · 1 HOUR
Ozone 0.054 ppm

10% higher than surrounding days

Before0.056 ppm Event0.054 ppm After0.028 ppm
6 monitors · 8-HR RUN AVG BEGIN HOUR

Atmospheric conditions

Nearby EPA weather observations
Humidity 78 %

About the same as surrounding days

Source: U.S. EPA AirData daily observations and, where available, nearby ASOS/AWOS surface observations. Values are descriptive medians over the retained monitor set; missing measurements remain missing. Transport and source evidence remain separate layers because this instrument pattern does not assign a cause by itself.

Measured daily PM2.5 at EPA monitors, as cigarette-equivalents
EPA monitors sit in metro areas, so the colour clusters there. Land between and beyond them is unmeasured, not clean: this map shows where IAQng has readings, not the extent of the smoke.
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Episode peak

-- cigarettes

The smoke map's scale, replayed over this event: the surface interpolates between covered metros' daily records, framed to the affected region. Hover for a reading, click a metro to pin it to the card. Days a monitor did not report draw nothing.

Affected metros

MetroPeak PM2.5Cigarettes, whole eventPeak dayAll-time standing
New Orleans-Metairie, LA 48.2 µg/m³ 4.0 Sep 4, 2000 #4 of its top days

"Cigarettes, whole event" totals a metro's ranked event days at 22 µg/m³ per cigarette: what a person outdoors there breathed across the event, as the illustration. "All-time standing" is where this episode's days sit in each metro's ranked record (worst-area measure, since 1999). Full local context is on each metro's Air Records page.

Public evidence library

What supports this account

Each card states what a source supports—and what it does not. Official records, research, reporting, community observations, and transparent inferences remain visibly different kinds of evidence.

3 retained sources

Official record

Texas/Louisiana wildfires — September 4th and 5th

NOAA Aeronomy Laboratory TexAQS 2000 Field Study

NOAA's TexAQS field-study newsletter documents the September 4-5 Texas/Louisiana wildfire outbreak. It reports a 30,000-acre fire south of Alexandria, about 50,000 Louisiana acres burned since August 31, satellite-observed smoke plumes over 100 miles long, and Louisiana/Texas marsh fires visible on September 4.

What it supports

This source supports a possible mechanism or occurrence; it does not establish the cause by itself.

Limit

The newsletter documents the statewide outbreak and long smoke plumes but does not explicitly attribute the New Orleans monitor's PM2.5 to a named fire.

Official record

New Orleans - Louis Armstrong surface observations reporting smoke

NOAA/NWS surface observations via Iowa Environmental Mesonet

New Orleans - Louis Armstrong, 5.7 km from the PM2.5 target monitor, reported the official present-weather code FU (smoke) during 4 observed hours inside the catalog event window.

What it supports

This source supports a possible mechanism or occurrence; it does not establish the cause by itself.

Limit

The surface code establishes smoke at the nearby airport; it does not identify whether the source was a wildfire, prescribed burn, agricultural fire, or another local fire.

Official record

FPA-FOD sixth-edition fire-occurrence records near the smoke observation

USDA Forest Service Rocky Mountain Research Station

FPA-FOD records a five-acre Louisiana wildfire 44.6 miles from the New Orleans surface station on September 4. NOAA's TexAQS field-study newsletter independently documents a much larger Louisiana wildfire outbreak on September 4-5, including a 30,000-acre fire south of Alexandria, roughly 50,000 acres burned since August 31, and satellite-observed smoke plumes more than 100 miles long.

What it supports

This source supports a possible mechanism or occurrence; it does not establish the cause by itself.

Limit

FPA-FOD is a fire-occurrence inventory, not a smoke-transport or PM2.5 source-apportionment product.

What remains uncertain

Status and provenance

Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.

This episode was grouped from the monitor record by the catalog pipeline and given its cause from the evidence listed above. It has not been individually reviewed and signed off, so its boundaries, cause, and name may change as evidence accumulates. Grouping policy common_sense_root_cause_grouping.v2. The cause label reflects the assembled evidence above, not an IAQng detection formula. If it is wrong, tell us.