Mobile Source Program
Over 70% of the total air pollution in San Diego County is generated from mobile sources. The purpose of the Mobile Source Program is to reduce public exposure to diesel particulate matter (PM) and smog-forming Nitrogen Oxide (NOx) emissions from diesel-powered trucks, buses, and other heavy duty equipment.
What Mobile Equipment Is Regulated and How?
Diesel-fueled vehicles weighing more than 10,000 lbs. are prohibited from idling for greater than 5 minutes unless the engine meets a low-NOx idling emission standard and the truck is labeled with a "Certified Clean Idle" sticker. This sticker is invalid when the truck is idling within a restricted area. School buses and other heavy duty vehicles must turn off the engine immediately upon arriving at a school and depart within 30 seconds of starting the engine.
Full Regulation (Commercial Vehicles)
Heavy-Duty Diesel Vehicle Idling Information
The In-Use Off-Road Diesel-Fueled Fleets Regulation (Off-Road Regulation) applies to all self-propelled off-road diesel vehicles 25 horsepower or greater used in California and most two-engine vehicles (except on-road two-engine sweepers). This includes vehicles that are rented or leased (rental or leased fleets). Equipment must be registered under the current owner with the California Air Resources Board(CARB) Diesel Off-Road Online Reporting System (DOORS ).Each vehicle is assigned anEquipment Identification Number (EIN) which must be labeled on both sides of the vehicle. Fleets must meet emission targets.
The California Air Resources Board (CARB) approved amendments to the In-Use Off-Road Diesel-Fueled Fleets Regulation (Off-Road Regulation) on November 17, 2022, aimed at further reducing emissions from the off-road sector.
2022 Amendments Regulatory Language
Off-Road Regulation Knowledge Center
- CARB Online Training
MS504 Online - How to Comply with the Off-Road Regulation - Overview (ca.gov)
The District was authorized in 2021 to conduct commercial harbor craft inspections including, but not limited to, ferries, excursion vessels, tugboats (including ocean-going tugs), towboats, push boats, crew and supply vessels, barge and dredge vessels, work boats, pilot vessels, and commercial passenger fishing vessels in San Diego County. A Compliance Advisory was issued on April 14, 2022 to notify vessel operators of these inspections.
The purpose of the Commercial Harbor Craft regulation is to reduce emissions of oxides of nitrogen (NOx), a key precursor to ozone formation, and diesel particulate matter (PM) from harbor craft engines. San Diego County is not in attainment with a federal and state health-based ground-level ozone standard. Ground-level ozone (or smog) is a respiratory irritant that negatively impacts at-risk people, including children, the elderly, and people with respiratory ailments. Reducing exposure to diesel PM can lower cancer risks and reducing exposure to ground level ozone will help to improve the health of all San Diego County residents and visitors.
2022 CHC Regulation Amendments Approved by Office of Administrative Law, Effective January 1, 2023.
On December 30, 2022, the Office of Administrative Law (OAL) approved amendments to the Commercial Harbor Craft (CHC) Regulation, section 2299.5, title 13, division 3, chapter 5.1 and section 93118.5, title 17, chapter 1, subchapter 7.5 of the California Code of Regulations (CCR). The amended CHC Regulation is effective January 1, 2023.
New Amended Regulation Text
Final Regulation Order (ca.gov)
The amended CHC Regulation will reduce emissions from harbor craft operated near California’s coast and improve public health in nearby communities, many of which are disadvantaged. By 2035, the amended CHC Regulation is expected to result in an 89 percent reduction of diesel particulate matter and a 52 percent reduction in nitrogen oxides. The amended regulation will also reduce the cancer risk to over 22 million residents who live near the coast and up to 50 miles inland.
To assist regulated parties with implementation, CARB staff is preparing several “fact sheet” documents to explain the core requirements of the amended regulation and posting the fact sheets on the CHC Program Factsheet Page as they become available.
Fact Sheets
Commercial Harbor Craft Factsheets | California Air Resources Board
Implementation Dates for the 2022 Amendments to the CHC Regulation
CHC Factsheet: Implementation Timeline | California Air Resources Board
How Do We Ensure Compliance?
The District has a Memorandum of Understanding in place with the California Air Resources Board to inspect certain mobile sources including off-road vehicles (construction equipment) and commercial harbor craft. This MOU and the California Health and Safety Code grants District staff the right of entry to conduct inspections and enforce air pollution regulations. District inspectors enforce mobile source requirements through unannounced inspections of on-road and off-road equipment and scheduled inspections of commercial harbor craft. Inspections of mobile sources may also occur concurrently with inspections of permitted stationary equipment.
How Can I Learn More?
CARB hosts informational trainings about these regulations at various locations throughout the year. To browse the training calendar navigate to the CARB training page, select Log In, then select "Prefer to browse first" under the New Students section.
You can also subscribe to receive CARB Training Updates via email or via text messages.
How Should I Respond to an SDAPCD Citation?
For more information about District violations please see our Violation Information page.
Off-Road Vehicle Violations
| Violation | Recommended Action |
| Failure to Report Vehicle in DOORS | Register the vehicle to your company in DOORS. If the vehicle has already been assigned an EIN you must move that EIN into your fleet. Vehicles should be registered within two weeks of the citation issuance. |
| Failure to Display EIN | The EIN should be properly displayed on both sides of the vehicle. Send pictures of both sides of the vehicle with the labels in place to the Air Quality Inspector within two weeks of the citation issuance. |
What Incentives are Offered for Mobile Source Compliance?
For eligible mobile source operators, the District administers a number of grant programs for partially funding the replacement of older engines or vehicles with new, less polluting models. Learn more
Compliance Division Contact
If you have any questions, please contact the SDAPCD Mobile Source Coordinator at apcdcomp@sdapcd.org or phone at (858) 586-2650.