EPA Air · stack tests by county and year

Air-emissions stack tests in San Joaquin County, California, 2026

• 187Stack tests

A stack test measures what a source actually emits, at the stack, against the limit in its permit. Each row below is one stack test recorded against a source in San Joaquin County, California during 2026. A facility can appear several times: this is the year’s record of what happened, not a list of places. The sources themselves are on the San Joaquin County facility page.

San Joaquin County, California, 2026

• Inspections 334

Air-emissions stack tests in San Joaquin County, other years

• 2025 413
• 2024 5,176
• 2023 551
• 2022 547
• 2021 2,302
• 2020 977
• 2019 385
• 2018 584
• 2017 581

Air-emissions stack tests recorded in San Joaquin County, California, 2026

Dates as filed by the agency that recorded the stack test. Figures from EPA’s ICIS-AIR download.