UNEXPLAINEDconfidence: low

No filed report covers this 9.7 ppb episode.

Sep 20, 2025, 12:00 AM · 2 hours duration · peak 9.7 ppb against background of 0.4 ppb · wind from the SE (139°, modelled)

What the records show

The monitor recorded 9.7 ppb at its peak on Sep 20, 2025, 12:00 AM, against a background near 0.4 ppb, over 2 hours.
ep:48-167-0005_20250920T05mon:48-167-0005
Through the episode the wind came from the south-east, modelled.
ep:48-167-0005_20250920T05
No facility in Galveston County filed a report listing this pollutant for this window.
ep:48-167-0005_20250920T05
The nearest facility with public coordinates is South Houston Green Power Site, 0.9 km away.
fac:RN103934493

Other explanations that fit

No matching report is not evidence of wrongdoing. Each of these would look the same in these records:

A release below the reportable quantity would leave no filed report at all.
Permitted, routine emissions can build up when the air is still and the plume stays low.
Ships, trucks and other mobile sources are not covered by this reporting system.
A source outside the searched counties would not appear in this search.

What would settle it

Sub-hourly data from the monitor for this window, which would show whether the rise was a sharp plume or a slow build.
Any complaint or investigation records the agency holds for this date.
Records of any emission event, maintenance, startup or shutdown at facilities upwind within 24 hours.

Ask for the records yourself

This is a formal request for public records under the Texas Public Information Act (Texas Gov’t Code § 552), not an accusation. Review it, download or copy it, and submit it to TCEQ Open Records.

Email TCEQ Open Records ↗Target: open.records@tceq.texas.gov · Texas Gov’t Code § 552

To: Texas Commission on Environmental Quality, Public Information Coordinator
Subject: Public information request, air monitoring and incident records, Texas City

Dear Public Information Coordinator,

Under the Texas Public Information Act, I request copies of the following records.

1. All ambient air monitoring data, at the finest time resolution held, for monitor 48-167-0005 from Sep 20, 2025, 12:00 AM to Sep 20, 2025, 2:00 AM local time.
2. Any citizen complaints, investigation reports or field notes relating to air quality in Texas City for that period.
3. Any emission event, maintenance, startup or shutdown notifications received for facilities in Galveston County covering that period, including any submitted after the deadline.

This is a request for public records. It is not an allegation that any facility did anything improper.

If any portion is withheld, please cite the exemption claimed and release the remainder. If fees will exceed $50, please contact me first with an estimate.

Sincerely,
[your name]
[your address]
[your email and phone]

Written by none (deterministic template), assembled directly from pipeline output. Rule-based verdict: UNEXPLAINED — no report lists the pollutant.