The San Joaquin Air Pollution Control District (SJVAPCD) hosted a public workshop on February 24, 2026, that discussed potential amendments to Rule 4101 – Visible Emissions. Rule 4101 requires that “A person shall not discharge into the atmosphere from any single source of emission whatsoever, any air contaminant, other than uncombined water vapor, for a period or periods aggregating more than three (3) minutes in and one (1) hour which is:
- As dark or darker in shade as that designated as No. 1 on the Ringelmann Chart, as published by the United States Bureau of Mines, or
- Of such opacity as to obscure an observer’s view to a degree equal to or greater than the smoke described above [20% opacity].
Currently individuals conducting Visible Emissions Evaluations (VEE) are required to attend a training and certification procedure conducted in accordance with U.S. EPA Method 9 to ensure compliance with standards set by the Clean Air Act (CAA); this Method 9 training is often referred to as “smoke school.” Rule 4101 currently defines an observer as “A human observer certified and trained by the California Air Resources Board (CARB).” CARB has historically offered Smoke School sessions throughout the year at various locations to certify observers. Recently, CARB has reduced the number of locations where certification is offered, forcing District staff and other trained observers from the industry to travel further to maintain their certifications; re-certification is required every 6 months. The current definition of an observer unintentionally restricts the use of approved alternative certification methods and effectively limits all training and certification used for compliance in its jurisdiction to that certification directly provided by CARB.
Proposed amendments to Rule 4101 would redefine an observer as, “A qualified human observer certified and trained in accordance with the procedures in EPA Method 9 or other alternative methods approved by EPA and the APCO.” This new definition would allow individuals to become certified by organizations other than CARB provided that the training and certification meets the standards set in EPA Method 9 or an approved alternative method.
Private-sector smoke school is and has always been the norm in most other states and some California air districts. Many state air agencies do not offer state-sanctioned smoke school at all. The proposed change will greatly increase the options available for smoke school training and recertification in the SJVAPCD reduce the need for travel for observers to maintain their certification. Additionally, in August of 2023, the U.S EPA approved an alternative method (ALT-152) that provides for how VEE observers can be certified using a Virtual Reality (VR) headset in lieu of in-person outdoor training. The new definition would also allow for the implementation of ALT-152 and similar new technologies once approved by EPA and the District.
These proposed changes are scheduled to be brought to the Governing Board on April 16, 2026. We expect they will be approved.
If you are in need of a Visible Emissions Evaluation, Trinity has certified observers available in offices throughout California. Please contact your local Trinity office for more information.
