SAN DIEGO (FOX 5/KUSI) — Sulfur emissions in the South Bay over the weekend exceeded federal guidelines, according to county officials.

The San Diego Air Pollution Control District regularly monitors average hydrogen sulfide emissions in the Tijuana River Valley, and this is not the first time elevated emissions have been recorded amid the ongoing sewage crisis.

Air advisory in southern San Diego due to hydrogen sulfide

From 9 p.m. on Sunday to 1 a.m. on Monday, the district said sulfur emission levels were recorded at 384 parts per billion (ppb). The Level 1 Federal Acute Exposure Guideline Level is 360 ppb.

The emissions were recorded using a monitor on top of Berry Elementary School, which is closest to where Saturn Boulevard crosses the Tijuana River. County officials said a drop in elevation there creates a small waterfall that can cause wastewater to foam and boost emissions.

By 10 a.m., officials said ppb levels had dropped to five.

The U.S. Environmental Protection Agency says that emission levels that exceed the Level 1 Federal Guideline can cause notable discomfort and irritation.

The public can sign up for sulfur emission notifications and get email or text alerts when levels surpass 30 ppb on the San Diego County Air Pollution Control District website.

Copyright 2026 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

For the latest news, weather, sports, and streaming video, head to FOX 5 San Diego & KUSI News.