California Air Resources Board

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CARB has a need to collect more emissions data from the California on-road motorcycle fleet. Prior to 2019 CARB’s emissions factor model (EMFAC) had not been updated for motorcycle exhaust and evaporative emissions for inventory since 2000 prompting the need to test more current models to reflect new technologies and emission rates. A recent 2019 CARB motorcycle project provided emissions data from 13 on-road motorcycles ranging from model year 2008 to 2019 used to update the current EMFAC model.

A new surveillance program is being developed to start by spring of 2024 to continue testing to provide more current emissions data to represent the newer models and technologies of the in-use fleet. The objective of this program is to solicit and procure privately owned motorcycles from the in-use CA fleet and test them for exhaust and evaporative emissions in CARB’s Riverside laboratory. The makes and models of the motorcycles selected to be procured and tested would represent the highest DMV registration populations and technology groups. Data collected from this test program will be used to update base emission rates and evaporative emission rates in EMFAC.

If you have questions, please contact the LDVSP Project Engineer, Steven Magbuhat (steven.magbuhat@arb.ca.gov) at (951) 542-3275 or Section Manager, Satya Sardar (satya.sardar@arb.ca.gov) at (951) 542-3376.

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CARB has a need to collect more data to characterize emissions from Class 2b-3 vehicles (8,501 lbs.-14,000 lbs. gross vehicle weight rating (GVWR)) that fall under the light heavy-duty (LHD) category. Under California’s EMissions FACtor inventory model (EMFAC), these vehicles are characterized as Light Heavy-Duty 1 (LHD1) (GVWR: 8,501 lbs. – 10,000 lbs.) and Light Heavy-Duty 2 (LHD2) (GVWR: 10,001 lbs. – 14,000 lbs.). These two vehicle classes make up about 4 percent of the California on-road fleet and are responsible for about 17 percent of statewide nitrogen oxides (NO_x) and about 18 percent of statewide on-road vehicle fine particulate matter (PM_2.5) emissions.

Considering LHD1 and LHD2 trucks will be part of CARB’s technology forcing regulations (e.g., CA Phase 2 GHG standards, Advanced Clean Cars II (ACC II) and Advanced Clean Truck (ACT) regulations), testing this class of vehicles is necessary to assess in-use emissions from light heavy-duty engines that are powered by gasoline and diesel under different driving conditions. In 2017, CARB conducted a research project to solicit and procure twelve diesel and gasoline light heavy-duty vehicles to collect emissions data that was used to update EMFAC.

Starting in 2023, CARB staff will be conducting a new LHD surveillance program to collect emissions data from this class of vehicles. The collected test data will be used to evaluate emission rates from chassis dynamometer testing and portable emissions measurement systems (PEMS) testing. A selected test vehicle from each class will be tested on-road with PEMS with and without towing a trailer. Additional testing over arterial and freeway driving cycles will help evaluate and update the model’s light-duty vehicle speed correction factors. Particulate matter (PM) and speciated emissions data will be collected to support air quality planning.

If you have questions, please contact the LDVSP Project Engineer, Steven Magbuhat (steven.magbuhat@arb.ca.gov) at (951) 542-3275 or Section Manager, Satya Sardar (satya.sardar@arb.ca.gov) at (951) 542-3376.

                                                                                                                                                                                            < BACK TO CURRENT ACTIVITIES

CARB has conducted light-duty surveillance programs since the 1970’s to solicit and procure a representative sample of the in-use fleet to collect emissions data that is used to update the CA emissions inventory models. The primary objective of a surveillance program is to collect emissions data that represent the in-use fleet. The data is used to update the current EMisson FACtor model (EMFAC) on a continual basis. This program tests passenger cars and trucks at CARB’s Southern California laboratory. Motor vehicle exhaust and evaporative emissions are measured and analyzed to support emissions inventory improvement and better understand the emission trends due to new vehicle technologies, populations and driving activity.

The current LDVSP is a three-year project and will begin in the fall of 2023. The collected test data will be used to evaluate engine start emissions (after varied periods of soak) and running exhaust emissions. Data collected from evaporative tests will be used to evaluate hot soak, diurnal, running loss and permeation emission factors used in the model. Additional testing over arterial and freeway driving cycles will help evaluate and update the model’s light-duty vehicle speed correction factors. This program also includes on-road emissions testing using portable emissions measurement systems (PEMS).

Special testing of vehicles under varying outside ambient temperatures at different relative humidity settings with the air conditioning on and off will be used to develop temperature, RH and AC correction factors used in the model. Particulate matter (PM) and speciated emissions data will be collected to support air quality planning. Additionally, the collection of ammonia (NH₃) data from exhaust emissions testing will be used to update the model.

If you have questions, please contact the LDVSP Project Engineer, Steven Magbuhat (steven.magbuhat@arb.ca.gov) at (951) 542-3275 or Section Manager, Satya Sardar (satya.sardar@arb.ca.gov) at (951) 542-3376.

Demonstrations of the impacts of exceptional events have been compiled by CARB and by individual air quality management districts (AQMD) and air pollution control districts (APCD).  Several examples are given below. 

Air Districts

Feather River AQMD

• 2020 and 2021 wildfire smoke impacts on PM2.5 monitors in Yuba City-Marysville Planning Area (District website)

Great Basin Unified APCD

• 2020 wildfire smoke impacts on PM10 monitors in Mammoth Lakes Planning Area (pdf on District website)

Imperial County APCD

• 2019 high wind dust impacts on PM10 monitors in Imperial Valley Planning Area (District website)

Mariposa County APCD

• 2021 and 2022 wildfire smoke impacts on ozone monitors in Mariposa County (District website)

Northern Sierra AQMD

• 2021 prescribed fire impacts on Grass Valley PM2.5 monitor in Nevada County (EPA website) 

Sacramento Metro APCD

• 2018 wildfire smoke impacts on PM10 monitors in Sacramento County (pdf on District website)

San Joaquin Valley APCD

• 2020 wildfire smoke impacts on PM2.5 monitors in the San Joaquin Valley (District website)

Siskiyou County APCD

• 2022 wildfire smoke impacts on the Yreka PM2.5 monitor in Siskiyou County (District website)

South Coast AQMD

• 2023 wildfire smoke impacts on Palm Springs ozone monitor in Coachella Valley (pdf on District website)

California Air Resources Board

2018 Ozone Exceptional Events

Southern Region

• CARB Demonstration (No public comments received prior to October 4, 2021 deadline)
• CARB Final Transmittal Letter

Northern Region

• CARB Demonstration (No public comments received prior to October 18, 2021 deadline)
• CARB Final Transmittal Letter
• Tuscan Buttes Q/D Addendum
  • Attachment A

2020 Ozone Exceptional Events

Southern Region

• CARB Demonstration (No public comments received prior to January 10, 2022 deadline)
• CARB Final Transmittal Letter 

Northern Region

• CARB Demonstration (No public comments received prior to December 20, 2021 deadline)
• CARB Final Transmittal Letter

Subject Matter Expert Review Panel on Nitrogenous Emissions from Soils: Final Report Completed with Public Workshop Anticipated late June 2025

The California Air Resources Board (CARB) invites you to participate in a public workshop to review the Final Report for the Soil Nitrogenous Emissions "Subject Matter Expert Review Panel (SMERP)" Contract (23RD017). As part of the SMERP, Dr. William Horwath (University of California [UC] Davis), Dr. Whendee Silver (UC Berkeley), Dr. Xia Zhu-Barker (University of Wisconsin -Madison), Dr. Martin Burger (California Department of Food and Agriculture [recently retired]; UC Davis), and Dr. Viney Aneja (North Carolina State University) conducted a comprehensive review of scientific literature, pertinent databases, and emission estimation methodologies that pertain to nitrogenous emissions from soils.”

Subject Matter Expert Review Panel on Nitrogenous Emissions from Soils 

CARB is seeking five technical experts to serve in the Subject Matter Expert Review Panel (SMERP) that will independently evaluate existing data and science to improve our current understanding of nitrogenous emissions, including oxides of nitrogen, nitrous oxide, and ammonia, from soils, particularly in California. 

Interested parties are encouraged to nominate their peers or apply themselves to be a member of the SMERP. Self-applicants must fill out the Conflict-of-Interest (COI) section prior to submission. Otherwise, CARB staff will contact the nominees to collect such information prior to SMERP member selection. Complete and submit this Form to abhishek.dhiman@arb.ca.gov by the deadline on 8/21/2023 at 5:00 PM PDT.  

Panel de Revisión de Expertos en la Materia sobre Emisiones Nitrogenadas del Suelo  

CARB está buscando cinco expertos técnicos para trabajar y ser parte del Panel de Revisión de Expertos en la Materia (SMERP, por sus siglas en Ingles) que evaluarán de forma independiente los datos y la ciencia existente para mejorar nuestra comprensión actual de las emisiones nitrogenadas, que incluye los óxidos de nitrógeno, el óxido nitroso y el amoníaco, de los suelos, en particular en California.  

Se le anima a las partes interesadas que nominen a colegas o apliquen para ser miembros del SMERP. Los autosolicitantes deben completar la sección de Conflicto de Intereses (COI). De lo contrario, el personal de CARB se comunicará con los nominados para recopilar dicha información antes de la selección de los miembros de SMERP. Complete y envíe este formulario a  abhishek.dhiman@arb.ca.gov antes de la fecha límite del Agosto 21 de 2023 a las 5:00 PM PDT. 

Meetings and Workshops