Right now
The most recent data we hold from AIRNOW arrived 31 hours ago, and this point is in it.
Nothing else has been detected within 20 km in the last 24 hours.
Reported by AIRNOW yesterday.
It is the 6th strongest of the 50 detections recorded within 20 km of this point since 18 April 2026. The last comparable one was on 2 September 2026. 3 more were recorded here in the fortnight before it.
What the source measured
AIRNOW reported: AQI: 115 (Unhealthy for Sensitive Groups) · PM2.5 AQI: 55 · Ozone AQI: 115
Urban PEI: 1,312,076 within a heuristic 5 km radius; not unique people.
Nearby, since 18 April 2026
- September 18, 2026 · score 50 · 0.0 km
- September 2, 2026 · score 59 · 0.0 km
- September 1, 2026 · score 66 · 0.0 km
How we know
One source: AIRNOW. Not yet confirmed by a second, independent source.
Our own score for this event is 50 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
Computed under scoring rules v5. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Air Quality |
| Severity | Low |
| Calamity Score (ours) | 50 / 100 |
| Legacy data-support index | 0.70/1 |
| Coordinates | 29.7510, -95.3510 |
| Nearest City | Houston (1 km) |
| Urban exposure index (PEI) | 1.3M within 5 km |
| Impact Tier | minor |
| Timestamp | 2026-09-18T00:00:00.000Z |
| Source | https://www.airnow.gov/ |
Physical priority index · v5. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: airnow. Occurrence: 2026-09-18T00:00:00.000Z.
First archived: 2026-08-03T23:55:35.099Z. Material modification: 2026-09-18T21:26:01.504Z.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
2026-09-18T21:26:01.504Z · model_change
Index 14 → 50; severity low → low; version 1 → 5.
Score Breakdown
Technical Details
| Aqi | 115 |
| Pm25Aqi | 55 |
| OzoneAqi | 115 |
| CategoryName | Unhealthy for Sensitive Groups |
| ReportingArea | Houston-Galveston-Brazoria |
| StateCode | TX |
| City | Houston |
Safety Information
When air quality is hazardous: stay indoors with windows closed, and run a filtered air purifier if you have one. Avoid outdoor exercise. Children, older adults and anyone with heart or lung conditions are affected first and worst — an N95 respirator helps outdoors, a cloth mask does not.
Series begins 8 March 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.
This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.
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