Primary and secondary NAAQS

• Primary NAAQS protect everyone including “sensitive populations” from health risk.
• Secondary NAAQS address decreased visibility and damage to crops and vegetation, buildings and property, and ecosystems.

The Environmental Protection Agency (EPA) sets requirements for both primary and secondary national ambient air quality standards (NAAQS) at a national level. Primary NAAQS protect everyone including “sensitive populations” (e.g., children, people with asthma, and the elderly) from health risk. Secondary NAAQS address decreased visibility and damage to crops and vegetation, buildings and property, and ecosystems. The standards correspond to a specific averaging time, and some pollutants have standards for more than one averaging time.

The current primary and secondary NAAQS are listed in the table below. The units of measure are parts per million (ppm) by volume, parts per billion (ppb) by volume, and micrograms per cubic meter of air (µg/m3).

Attainment and nonattainment areas

• Facilities in nonattainment areas will be subject to more restrictive permitting, and to mandated federal pollution control measures.

The United States is divided into different geographic areas known as “attainment areas.” An area that does not meet its national ambient air quality standards (NAAQS) is called a nonattainment area, and the Clean Air Act (CAA) requires each state to develop a State Implementation Plan (SIP) to identify sources of pollution and determine which reductions are required to meet federal air quality standards. Being out of attainment (i.e., nonattainment) can result in an area losing federal funding for highways and other transportation projects.

Facilities in nonattainment areas will be subject to more restrictive permitting, and the area will be subject to mandated federal pollution control measures. In addition, the federal government can impose special requirements for vehicles, such as emissions testing, that can affect ordinary citizens. Certain fuel blends may also be required for the area.

Once an area is found to be in nonattainment, the state, county, or area has three years to address the pollution and create an implementation plan describing how it will meet and maintain the standards. The plan must address reducing the criteria pollutants through pollution controls for stationary sources and vehicle emissions testing requirements for mobile sources.

Global Warming Potential

• Gases with a higher GWP absorb more energy, per pound, than gases with a lower GWP, and thus contribute more to warming the Earth.

For each greenhouse gas (GHG), a Global Warming Potential (GWP) has been calculated to reflect how long it remains in the atmosphere (on average) and how strongly it absorbs energy. Gases with a higher GWP absorb more energy, per pound, than gases with a lower GWP, and thus contribute more to warming the Earth.

The GWP, also known as “carbon dioxide equivalent,” allows comparisons of the global warming impacts of different gases. Specifically, it measures how much energy the emissions of one ton of a gas will absorb over a given period relative to the emissions of one ton of carbon dioxide (CO2). The time period usually used for GWPs is 100 years.

• CO₂, by definition, has a GWP of one regardless of the time period used, because it is the gas being used as the reference. CO₂ remains in the climate system for a very long time; CO₂ emissions cause increases in atmospheric concentrations of CO2 that will last thousands of years.
• Methane (CH₄) is estimated to have a GWP of 28–36 over 100 years. CH₄ emitted today lasts about a decade on average, which is much less time than CO₂. But CH₄ also absorbs much more energy than CO₂. The net effect of the shorter lifetime and higher energy absorption is reflected in the GWP. The CH₄ GWP also accounts for some indirect effects, such as the fact that CH₄ is a precursor to ozone (O₃), and O₃ is itself a GHG.
• Nitrous oxide (N₂O) has a GWP 265–298 times that of CO2 for a 100-year timescale. N₂O emitted today remains in the atmosphere for more than 100 years, on average.
• Fluorinated gases such as chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF₆) are sometimes called high-GWP gases because, for a given amount of mass, they trap substantially more heat than CO₂. The GWPs for these gases can be in the thousands or tens of thousands.

Federal mandatory reporting

• GHG reporting is required for sources that emit 25,000 metric tons or more of CO₂ equivalent per year in the U.S.
• There are three type of greenhouse gas source categories “all-in”, threshold, and stationary fuel combustion sources.

The Environmental Protection Agency’s (EPA’s) 2009 Mandatory Reporting of Greenhouse Gases Rule at 40 CFR 98 requires large sources and suppliers to report their emissions of greenhouse gases (GHGs) to the EPA. The reporting program is called the Greenhouse Gas Reporting Program (GHGRP).

According to the EPA, more than 13,000 facilities in the U.S. are covered by the GHGRP.

Part 98

Part 98 is divided into 43 subparts. Subpart A lists the general reporting and recordkeeping requirements to apply to all facilities and suppliers subject to the rule. It also contains the applicability provisions, the reporting schedule, and definitions.

Subpart A also contains the overarching requirements of the rule. For example, there are flow meter accuracy and calibration provisions that apply when they are specified in a particular subpart. The specific types of monitoring equipment needed is defined in the source category subpart, however.

Subparts C through UU contain specific requirements for each of the source categories covered by the rule. The company must follow all the subparts that pertain to the facility. For example, if the facility produces adipic acid and has fuel combustion sources, the company needs to read subpart C, general stationary fuel combustion sources, and subpart R for adipic acid production.

Each subpart defines the specific source category it covers and lists the monitoring methods, equations to calculate emissions, and specific data elements to report or record for that source category.

Who’s covered?

40 CFR part 98 requires reporting by 41 industrial categories. Reporting is required for sources that emit 25,000 metric tons or more of carbon dioxide (CO₂) equivalent per year in the U.S. This includes 33 different types of direct emitters and six types of suppliers of fuel or industrial greenhouse gases. In addition, facilities that inject CO₂ underground for geologic sequestration, enhanced oil recovery, or other purpose are subject to mandatory GHG reporting.

Applicability for facilities depends on the source categories located at the facility and, for some facilities, the emission level or production capacity. Reporting is at the facility level except for certain suppliers of fossil fuels and industrial greenhouse gases.

The emissions reporting requirements for direct emitting facilities are found in 40 CFR 98.3(c)(4), and the emissions reporting requirements for suppliers are found in 98.3(c)(5)

A facility is defined as the physical property, plant, building, structure, source, or stationary equipment:

• On contiguous or adjacent properties;
• In actual physical contact or separated solely by public roadway or other public right of way; and
• Under common ownership or common control.

Once the company establishes the facility boundary, applicability depends on the source categories that are present. The rule defines three types of source categories:

• “All-in” source categories,
• Threshold categories, and
• Stationary fuel combustion sources.

If the company has multiple source categories on site, do not designate the facility as being a single source category (for example, based on determining the predominant operation). Rather, evaluate each source category to assess applicability. Keep in mind that a facility with multiple source categories can become subject to the rule because of just one category. But if the company is subject to the rule, then the GHG report must cover ALL source categories for which methods are provided in the rule — not just the source category that triggered applicability.

State GHG reporting

• At least 21 states have GHG reporting requirements that differ from the federal GHG reporting requirements.

At least 21 states have greenhouse gas (GHG) reporting requirements that differ from the federal GHG reporting requirements. For example, Washington State’s Clean Air Rule calls for industries to report on 10,000 metric tons or more of carbon dioxide (CO₂) or CO₂ equivalents — by contrast, the federal reporting threshold is 25,000 metric tons or more of CO₂ equivalents. North Carolina, however, encourages but does not require GHG reporting from large, permitted facilities.

Some states piggyback off the federal GHG Reporting Program (GHGRP) and extract state-specific data from the report, and states may also have GHG reporting deadlines that are different from the annual federal deadline of March 31.

The bottom line is that the company must know whether the state has additional GHG reporting requirements for the industry or the facility’s emissions. The following states have different or additional GHGRP requirements:

• California
• Colorado
• Connecticut
• Delaware
• Florida
• Hawaii
• Iowa
• Maine
• Maryland
• Massachusetts
• Minnesota
• New Hampshire
• New Jersey
• New Mexico
• New York
• North Carolina
• Oregon
• Pennsylvania
• Rhode Island
• Washington
• West Virginia

HAP list

• There are 187 HAPs that the EPA is required to regulate under the CAA.

The current list of hazardous air pollutants (HAPs) that the Environmental Protection Agency (EPA) is required to regulate under the Clean Air Act (CAA) includes 187 chemicals, enumerated in the table below by their Chemical Abstracts Service (CAS) numbers and chemical names.

NOTE: For all listings below which contain the word “compounds” and for glycol ethers, the following applies: Unless otherwise specified, these listings are defined as including any unique chemical substance that contains the named chemical (i.e., antimony, arsenic, etc.) as part of that chemical’s infrastructure.

Major and minor sources

• The EPA regulates major and minor stationary sources of HAPs.
• Major sources that take steps to upgrade their facilities or install pollution-reduction equipment can potentially be reclassified as area sources.
• While individual area sources have much lower emissions than individual major sources, these sources can be numerous and widespread.

The Environmental Protection Agency (EPA) regulates two types of stationary sources of hazardous air pollutants (HAPs):

• Major sources are those that emit 10 tons per year (tpy) of any of the 187 listed toxic air pollutants, or 25 tpy of a mixture of air toxics. These sources may release air toxics from equipment leaks, during the transfer of materials, or during discharge through emissions stacks or vents.
• Area sources (or minor sources) are smaller-sized facilities that release lesser amounts of toxic pollutants into the air. Area sources emit less than 10 tpy of a single air toxic or less than 25 tpy of a combination of air toxics.

The 1990 Clean Air Act (CAA) amendments directed the EPA to set standards for all major sources of air toxics and some area sources that are of particular concern.

Major sources

For major sources, the EPA establishes maximum achievable control technology (MACT) standards. The EPA applies MACT standards for most source categories based on the emission controls that are being achieved by the best-controlled sources in that category. While MACT standards for existing major sources may be less stringent than for new sources, existing sources must meet one of the following:

1. For sources in categories or subcategories containing 30 or more sources, at least as stringent as the average emission limitation met by the best performing 12 percent of existing sources.
2. For source in categories containing less than 30 sources, at least as stringent as the average emission limitation met by the best performing five sources.

MACT can be limits on emissions of HAPs, or it can involve technology requirements for controlling emissions. When setting MACTs, the EPA must consider the cost, energy consumption, and other environmental consequences such as waste disposal and water quality.

If the company is a major source of HAPs, they must meet certain emission performance standards, which involves:

1. Meeting air pollution control limits set by the federal government based on performance standards that have been achieved in practice by a similar industry, process, or equipment.
2. Obtaining a Title V operating permit.

In the past, once a business qualified as a major source, the business had to continue as a major source, even if it reduced its emissions to below major source levels. However, a January 2018 memo from the EPA reversed this long-standing policy known as “once in, always in.” This means that major sources can take steps to upgrade their facilities or install pollution-reduction equipment and potentially be reclassified as area sources.

Area (or minor) sources

A facility that cannot emit a level of criteria pollutants or HAPs equal to a major source is called an area source (or minor source). To be an area source, the business must:

• Have a potential to emit (PTE) below major source levels, or
• Have a PTE at or above major source levels, but limit its operations or emissions. These businesses must obtain an operating permit from the state air pollution control agency which places limits on the facility’s operations or emissions. This could include specific restrictions or requirements on:
  • The use, operation, and maintenance of air pollution control equipment;
  • Operating time;
  • The types and amounts of input materials used (e.g., fuel or solvents); and
  • Recordkeeping and reporting.

While individual area sources have much lower emissions than individual major sources, these sources can be numerous and widespread. The collective emissions from area sources can add up to more than the emissions from major sources. Examples of area sources are gas stations and dry cleaners, and these area sources may also be subject to regulation.

The EPA says that to use a limitation to reduce the maximum capacity and be considered an area source, the limitation must be an unchanging and unavoidable physical constraint. The constraint(s) must result in predictable upper limits on the facility operations and capacity.

Area sources must meet generally available control technology (GACT). These are less stringent standards than those required by major sources and are usually easier to meet.

NESHAP source category list

• There are numerous NESHAP source categories each with unique subparts under which they are regulated.

The following table lists source categories under the National Emissions Standards for Hazardous Air Pollutants (NESHAPs) and the subpart under which they are regulated.

Stationary source servicing (section 608)

• Only three types of releases of ODS or their substitutes are permitted.

Stationary refrigeration, air conditioning, and heat pump equipment is used in all types of buildings. The Environmental Protection Agency (EPA) regulations under 608 of the Clean Air Act (CAA) address the handling and recycling of refrigerants used in these types of equipment. These regulations are designed to:

• Prevent the release of ozone-depleting substances (ODS) when stationary equipment is being serviced, maintained, repaired, or disposed.
• Reduce the use and emission of ODS from stationary equipment.
• Maximize the recapture and recycling of ODS from stationary equipment.
• Ensure the safe disposal of ODS.

EPA regulations under section 608 prohibit anyone from intentionally venting ODS or their substitutes while maintaining, servicing, repairing, or disposing of air-conditioning or refrigeration equipment. Only three types of releases are permitted:

1. De minimis quantities of refrigerant released while making good faith attempts to recapture and recycle or safely dispose of refrigerant, including releases that occur when connecting or disconnecting hoses to charge or service appliances.
2. Refrigerant emitted during the normal operation of air-conditioning and refrigeration equipment (as opposed to during the maintenance, servicing, repair, or disposal of this equipment), such as from mechanical purging and leaks. However, the EPA requires that leaks above a certain size be repaired in equipment that contains 50 pounds of refrigerant or more.
3. Releases of substitute refrigerants that EPA has determined do not pose a threat to the environment.

The EPA requires technicians who service stationary refrigeration and air-conditioning equipment to follow specific practices. These practices are meant to maximize recovery and recycling of refrigerants, which can be ODS or potent greenhouse gases. Different practices apply to different equipment, depending on their size and manufacture.

Refrigerant stationary source recordkeeping and technician certification

• Technicians must keep a copy of their proof of certification at their place of business.
• Technicians are required to pass an EPA-approved test to earn Section 608 Technician Certification.
• The EPA has developed four types of technician certifications.

Recordkeeping

EPA regulations under section 608 include recordkeeping requirements that are specific to different persons or companies involved with stationary refrigeration and air-conditioning equipment.

• Technicians must keep a copy of their proof of certification at their place of business. Technicians servicing appliances that contain 50 or more pounds of ozone-depleting refrigerant must provide the owner with an invoice that indicates the amount of refrigerant added to the appliance. This requirement also applies to HFC and other non-exempt substitute refrigerants. Technicians must provide records of leak inspections and tests performed to verify repairs of leaking appliances. Technicians disposing of appliances containing between five and 50 pounds of refrigerant must keep records of the disposal.
• Owners or operators of appliances that contain 50 or more pounds of ozone-depleting refrigerant must keep servicing records documenting the date and type of service, as well as the quantity of refrigerant added. This requirement also applies to HFC and other non-exempt substitute refrigerants. Owners or operators will also be required to maintain records of leak inspections and tests performed to verify repairs of leaking appliances and must submit a report to the EPA for any appliance containing 50 or more pounds of refrigerant that leaks 125 percent or more of the full charge in a calendar year. This report must describe efforts to identify leaks and repair the appliance.
• Reclaimers must maintain records of the names and addresses of persons sending them material for reclamation and the quantity of material sent to them for reclamation. This must be maintained on a transactional basis. Reclaimers must report to the EPA by the first of February annually the total quantity of refrigerant sent to them the previous year for reclamation, the mass of refrigerant reclaimed that year, and the mass of waste products generated that year.

Technician certification

Technicians are required to pass an EPA-approved test to earn Section 608 Technician Certification. The tests are specific to the type of equipment the technician seeks to work on. Tests must be administered by an EPA-approved certifying organization. Section 608 Technician Certification credentials do not expire.

A technician is an individual who performs any of the following activities:

• Attaching and detaching hoses and gauges to and from an appliance to measure pressure within the appliance.
• Adding refrigerant to or removing refrigerant from an appliance.
• Any other activity that violates the integrity of a motor vehicle air conditioner (MVAC)-like appliance or small appliance (other than disposal).

Apprentices are exempt from certification requirements provided they are closely and continually supervised by a certified technician.

The EPA has developed four types of certifications:

1. For servicing small appliances (Type I).
2. For servicing or disposing of high- or very high-pressure appliances, except small appliances and MVACs (Type II).
3. For servicing or disposing of low-pressure appliances (Type III).
4. For servicing all types of equipment (Universal).

Motor vehicle air-conditioner servicing (Section 609)

• The MVAC regulations are designed to prevent the release of refrigerants during servicing.
• Technicians who repair or service MVAC systems must be trained and certified under an EPA-approved technician training and certification program.
• New service shops or shops servicing MVAC systems for the first time must certify to their EPA Regional Office that they have acquired and are properly using approved refrigerant handling equipment.

Under 609 of the Clean Air Act (CAA), the Environmental Protection Agency (EPA) regulates the servicing of motor vehicle air conditioners (MVACs) and MVAC-like equipment used in farm and heavy-duty equipment. The EPA’s regulations are designed to prevent the release of refrigerants during servicing. Basic compliant points include:

• Refrigerant: Must be approved by the EPA and cannot be intentionally released (vented) to the environment.
• Servicing: When payment of any kind is involved (including non-monetary), any person working on an MVAC system must be certified under 609 of the CAA and they must use approved refrigerant handling equipment.
• Reusing Refrigerant: Refrigerant must be properly recycled or reclaimed before it can be reused, even if it is being returned to the vehicle from which it was removed.

The EPA evaluates alternative refrigerants under its Significant New Alternatives Policy (SNAP) program, established under 612 of the CAA. SNAP lists refrigerants for MVAC systems as either “acceptable subject to use conditions” or “unacceptable.” Each SNAP-approved refrigerant is required to be used with a unique set of fittings to prevent the accidental mixing of different refrigerants.

When an MVAC system enters the waste stream, the final person in the disposal chain must remove the refrigerant, or make certain that their customer has removed it, prior to disposal.

Technician training and certification

Technicians who repair or service MVAC systems for consideration (e.g., either payment or bartering), regardless of what refrigerant is used in the system, must be trained and certified under section 609 by an EPA-approved technician training and certification program. Technicians must use refrigerant handling equipment that has been certified by the EPA or an independent standards testing organization approved by the EPA to certify equipment.

Certified servicing equipment must be used to remove refrigerant prior to servicing or repairing an MVAC system or conducting any other service on a vehicle during which discharge of refrigerant can reasonably be expected. Recovered refrigerant must be either recycled or reclaimed before it can be recharged into an MVAC system, even if the refrigerant is being returned to the system from which it was removed.

Recovered refrigerant can either be recycled on-site using approved equipment designed to both recover and recycle refrigerant or sent off-site to a reclamation facility to be purified according to Air-Conditioning & Refrigeration Institute (ARI) Standard 700. Recycling removes impurities and oil, while reclamation returns the refrigerant to virgin specifications. Refrigerant sent off-site must be sent to an EPA-certified refrigerant reclaimer.

Recordkeeping requirements

New service shops or shops servicing MVAC systems for the first time must certify to their EPA Regional Office that they have acquired and are properly using approved refrigerant handling equipment. This is a one-time requirement. If a shop has certified ownership of a piece of chlorofluorocarbons (CFC)-12 or HFC-134a equipment at any time in the past, the shop is not required to re-submit certification to the EPA when they purchase new equipment. This applies even if the shop purchases equipment for a different refrigerant.

To certify equipment, provide a written statement signed by the person who acquired the equipment (this person may be the owner of the establishment or another responsible officer). Send the signed certification statement to the EPA Regional Office responsible for the state in which the establishment is located.

Service shops must maintain on-site records proving that each person using servicing equipment has been properly trained and certified under 609, as well as records of the name and address of any facility to which they send recovered refrigerant. These records must be maintained for three years.

CA Advanced Clean Fleets

The Advanced Clean Fleets (ACF) Regulation complements the California Air Resources Board’s (CARB’s) Advanced Clean Trucks regulation to speed up the adoption of zero-emission technologies into the state’s truck and bus fleets that are well-suited for electrification. The rules mandate that targeted fleets lower emissions by phasing in the use of zero-emission vehicles (ZEVs) and that manufacturers only make ZEV trucks beginning with model year (MY) 2026.

It’s important to note that on January 13, 2025, California withdrew the state’s request for a Clean Air Act waiver for the ACF Regulation. CARB is considering its next actions. The agency isn’t enforcing the parts of the ACF rule that need federal permission, like the sections that apply to high-priority and drayage fleets. Not all parts of the ACF rule need this federal permission. ACF section for state and local government fleets is still in effect.

Requirements for state and local government fleets

The rule applies to agencies with authority in California that own, lease, or operate one or more vehicles in California that weigh more than 8,500 pounds. It can be a state or local government agency, including a city, county, public utility, special district, local agency or district, or a public agency of the State of California. It also applies to any department, division, public corporation, or public agency of the State of California.

Compliance requirements for state and local government fleets

Starting on January 1, 2024, half of a fleet’s annual vehicle purchases must be ZEVs. Beginning on January 1, 2027, all vehicle purchases should be ZEVs. Different parts of the same state or local government agency can meet these requirements together instead of separately.

Vehicles that are nearly zero-emission and have the MY 2035 or earlier are counted the same as ZEVs for this requirement. Any new vehicles with internal combustion engines (ICE), MY 2024 or newer, added to the California fleet after 2023 must meet California emissions standards. Any used ICE vehicle added must have an engine MY between 2010 and 2023.

State and local governments can choose to use the ZEV Milestones Option (available until January 1, 2030), which allows them to gradually introduce ZEVs into their fleets based on the suitability of different vehicles. If a fleet owner decides to use this option, they must report it. Once they choose this option, they can't switch back to the state or local government fleet requirements.

If a government fleet is small (with 10 or fewer vehicles) or operates in certain low-population areas and they're following the ZEV Purchase Schedule, they can wait until January 1, 2027, to start buying only ZEVs. But even these fleets have to start following other rules beginning on January 1, 2024, like reporting.

Recordkeeping and reporting requirements for state and local governments

Fleet owners need to complete and submit an annual report about their California fleet every year by April 1 through April 1, 2045. The report is based on the fleet as it stands on the first day of the year.

If a group of agencies decides to work together, each one still has to submit individual reports. The group may consist of different departments, divisions, districts, subsidiaries, or agencies.

Fleet owners must maintain records of the information they report and any related documents for at least five years. They must provide an electronic or paper copy within 72 hours of a written or verbal audit request from CARB.

CA Air Toxics Program

• The Air Toxics Program is a California-specific program designed to identify and control the exposure of toxic air emissions from stationary, area, and mobile sources.
• The program consists of several different pieces of legislation, each with specific requirements.

In an effort to identify and control the exposure of toxic air emissions for all Californians, the California Air Resource Board (CARB) established the Air Toxics Program. This program consists of several components, including identification and notification as well as addressing the impacts on communities and children.

Key foundational legislation aimed at the reduction of exposure to air toxics in the state include the Toxic Air Contaminant Identification and Control Act (AB 1807), the Air Toxics “Hot Spots” Information and Assessment Act (AB 2588), the Children’s Environmental Health Protection Act (SB 25), and the Community Air Protection Program (AB 617).

CA Greenhouse Gas Emission Inventory Program

• The California-specific program was established as a means to combat climate change by tracking the historical progress of reducing greenhouse gas (GHG) emissions from economic sector sources.
• The program is part of the California Global Warming Solutions Act, which is designed to show progress towards the GHG reduction goals, including carbon neutrality.

The GHG Emission Inventory Program collects and compiles data on GHG emissions from economic sector sources including agriculture, commercial, forestry, electrical, industrial, residential, and transportation.

This program works in concert with various initiatives under the California Global Warming Solutions Act to show progress toward meeting the state’s GHG reduction goals and mitigation, with a goal of achieving carbon neutrality by 2045 or earlier.

Greenhouse Gas Inventory

California-specific legislation makes the California Air Resources Board (CARB) responsible for developing and maintaining an inventory of greenhouse gas (GHG) emissions to track progress toward the state’s GHG reduction goals, including carbon neutrality.

CARB must monitor and regulate the following GHGs, which are known as “high global warming potential gases":

• Carbon dioxide
• Methane
• Nitrous oxide
• Sulfur hexafluoride
• Hydrofluorocarbons
• Perfluorocarbons
• Nitrogen trifluoride

The GHG inventory is part of the state’s GHG Emission Inventory Program under the California Global Warming Solutions Act.

CA State Implementation Plans

Federal clean air laws require areas with unhealthy levels of ozone, particulate matter, carbon monoxide, nitrogen dioxide, and sulfur dioxide to develop State Implementation Plans (SIPs). These comprehensive plans outline how an area will achieve national air quality standards.

SIPs are a collection of plans, programs, rules, regulations, and controls. Many of California's SIPs rely on strategies like vehicle emission standards, fuel regulations, and limits on emissions from consumer products.

The California Air Resources Board (CARB) is the lead agency for SIP development. Local air districts and other agencies contribute to SIP elements, which are reviewed and approved by CARB. Approved SIP revisions are then submitted to the U.S. Environmental Protection Agency (U.S. EPA) for final approval.

California's SIP is complex due to its large population and diverse geography. The state has a long history of air pollution issues and has implemented numerous measures to improve air quality. These are key components of California's SIP:

• Emissions inventory: A detailed accounting of all air pollution sources.
• Attainment demonstrations: Analyses showing how the state will achieve air quality standards.
• Control measures: Specific actions to reduce emissions, such as vehicle regulations and industrial controls.
• Emergency plans: Procedures for responding to air pollution episodes.

Challenges and innovations

California has faced significant challenges in meeting air quality standards but has also been a leader in air pollution control. Innovative strategies include:

• Zero-emission vehicle mandates to promote electric vehicles;
• The Cap-and-Trade Program, a market-based approach to reduce greenhouse gas emissions; and
• Transportation control measures to reduce vehicle emissions through congestion pricing, public transportation, and active transportation infrastructure.

Statewide efforts

U.S. EPA has approved portions of California's 2018 Infrastructure SIP but has also proposed disapprovals and implemented federal plans. California is currently working on a 2024 Good Neighbor SIP to address these issues.

California's SIP is an ongoing process. The state's commitment to clean air has led to significant improvements, but challenges remain.

CA Clean Truck Check (HD I/M)

Under the California Air Resources Board’s (CARB’s) Clean Truck Check (CTC) regulation (originally known as the Heavy-Duty Inspection and Maintenance regulation, or HD I/M, regulation), owners of vehicles with a gross vehicle weight rating (GVWR) of 14,001 pounds or more that operate in California and are powered by a non-gasoline engine must register the vehicle in CARB’s Clean Truck Check–Vehicle Inspection System (CTC-VIS) database, pay an annual compliance fee, and upload onboard diagnostic (OBD) data to CARB twice a year.

Registration

The Clean Truck Check program requires all non-gasoline-powered internal combustion engine (ICE) vehicles that operate in California with a GVWR of 14,001 pounds or more to be registered in CARB’s CTC-VIS database. Part of registering includes paying a per-vehicle annual compliance fee ($30 per vehicle for 2023 and 2024). Here is the schedule for the fees:

• 2023 fees were due by January 31, 2024.
• 2024 fees were due between July and December 2024.
• 2025 fees are due between January and June 2025.

The month the registration fee is due is based on the “compliance months.” For a California-registered vehicle, the compliance months will be based on the month the vehicle registration expires and six months later. Here is a table that shows this:

Emissions tests/OBD downloads

Vehicle owners or operators must upload onboard diagnostic (OBD) downloads twice a year to CARB. The purpose of this test is to prove the vehicle is operating within its designed emissions parameters.

If the vehicle does not have an acceptable OBD system, such as the vehicle has an engine older than model year 2013, the tester must do a smoke opacity test and visual inspection of all emissions components.

The OBD/smoke opacity test submissions are due based on the vehicle's plate expiration date (if registered/plated in California) or the last digit of the VIN (if registered/plated in another state). See the compliance months tables above. The test and submission can be done up to 90 days in advance of the due date.

The OBD or smoke opacity test must be done by a CARB-licensed HD I/M tester. Becoming a licensed tester involves completing the CARB Heavy Duty Inspection and Maintenance Tester Course, passing the final examination, and being issued an HD I/M Tester Identification Number by CARB. Licensed testers must use CARB-approved electronic OBD download devices or smoke opacity testers.

If the vehicle has a malfunction indicator lamp or an active trouble code related to emissions, the vehicle will not pass the test and must be repaired.

Also, if the vehicle had a diagnostic trouble code that was reset prior to the test, the software the tester uses will verify that the vehicle has done at least five warm-up cycles without the trouble code returning. If the trouble code was a permanent diagnostic trouble code, the vehicle must have undergone at least 15 warm-up cycles without the trouble code returning to pass the test.

Exemptions from the Clean Truck Check program include:

• Zero-emission vehicles,
• Military tactical vehicles,
• Emergency vehicles,
• Historical vehicles,
• New vehicles with engines certified to the most stringent optional NO_x standard (only during the first four years of Clean Truck Check implementation),
• Motorhomes registered outside of California,
• Vehicles operating under an experimental permit, and
• Vehicles operating in California under a five-day temporary pass.

CA Diesel Enforcement

The California Air Resources Board (CARB) adopts a compliance-focused strategy to identify and tackle the most significant instances of noncompliance. This approach is complemented by effective deterrent measures to encourage adherence to regulations. CARB is actively investing in and improving technologies to enhance the detection of emission sources. For instance, the Portable Emissions Acquisition System (or PEAQS) is a mobile emissions monitoring device that identifies high-emitting vehicles in real time. These initiatives not only ensure compliance but also support CARB's commitment to environmental justice by providing communities with valuable information to advocate for positive change.

Under the CARB diesel enforcement (CDE) programs, drivers are required to comply with various regulations related to diesel emissions and vehicle maintenance. Here are some key requirements:

• Periodic Smoke Inspection Program (or PSIP): Diesel-powered vehicles with a Gross Vehicle Weight Rating (GVWR) of 6,001 pounds or more are subject to annual emissions inspections once the vehicle is four years old. Certain vehicles with a GVWR of 6,001 to 14,000 pounds may be eligible for every-other-year testing.
• Heavy-Duty Diesel Vehicle Inspection Program (or HDVIP): Heavy-duty diesel vehicles operating in California can be inspected at any time to ensure they meet the emissions standards that were in place when the engine was manufactured. The inspection also includes verifying the presence and integrity of required emission control system components.
• Idling Reduction Program: Idling of heavy-duty vehicles is limited to no more than five minutes in California. Vehicles with a model year 2008 or newer engine must have an automatic shutdown feature that turns off the engine after five minutes of idling, with some exceptions.
• Transport Refrigeration Units (TRUs): TRUs, which are refrigeration systems powered by diesel engines used in the transportation of goods, must meet specific emissions standards. This includes limiting emissions to 0.02 grams per brake horsepower-hour or being equipped with an emission system meeting the Level 3 verified diesel emission control strategy (or VDECS) retrofit standards.

Impact

CARB's CDE programs have successfully reduced diesel emissions, improving air quality and protecting public health. They've also promoted cleaner diesel technologies and supported the adoption of alternative fuels.

Challenges and future directions

CARB faces challenges such as the need for ongoing inspections and staying ahead of emerging technologies. Future directions may include expanding its focus to newer diesel technologies and continuing to promote education and outreach.

CA Diesel Vehicles

The U.S. Environmental Protection Agency (U.S. EPA) and California Air Resources Board (CARB) both regulate the emissions from diesel-powered vehicles. U.S. EPA regulations apply nationwide, and the CARB regulations apply to vehicles operating in California.

U.S. EPA

U.S. EPA has traditionally:

• Placed emissions limits on vehicle emissions that manufacturers must meet, and
• Enforced rules that make it illegal to tamper with the emissions systems on vehicles.

The emissions limits placed on diesel power vehicles over the years (since the 1990s) have required a reduction in:

• PM emissions — Particulate matter (PM), also known as diesel particulate matter, is the solid emission released by a diesel-powered vehicle. Additionally called diesel soot, PM emissions are the black exhaust that older diesel vehicles release.
• NO_x emissions — Nitrogen oxides (NO_x) and other gaseous exhaust emissions are released from an internal combustion engine that are damaging to the atmosphere.
• CO₂ emissions — Carbon dioxide (CO₂) is a gaseous exhaust that is released from an internal combustion engine that is damaging to the atmosphere.

Major changes in the limits and their impact include the following:

• 2007: The required reduction in PM emissions (PM emissions were limited to 0.25 grams per brake horsepower-hour (g/bhp-hr)) led to the installation of diesel particulate filters on most diesel-powered vehicles.
• 2010: The required reduction in specific gases (NO_x limited to 1.2 g/bhp-hr based on the manufacturer’s fleet average) led to the installation of selective catalytic reduction (SCR) systems on most diesel-powered vehicles. These systems inject diesel exhaust fluid (DEF) into the exhaust stream, resulting in the NO_x being broken into nitrogen and water.

Under the legacy U.S. EPA rules, a vehicle must meet the emissions standards that were in place the year the engine was manufactured and have all the emissions control components on it that were required the year the vehicle was manufactured.

U.S. EPA's Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards rule was finalized in 2022. These regulations apply to the manufacturers of on-highway heavy-duty trucks and engines and implement more stringent emissions standards over a wider range of operational conditions. Implementation begins with model year (MY) 2027.

Technically, this was the first rule in U.S. EPA's Clean Truck Plan. The second was the more stringent emissions standards for light- and medium-duty trucks, and the third was the Greenhouse Gas (GHG) Emissions Standards for Heavy-Duty Vehicles - Phase 3.

U.S. EPA’s GHG Emissions - Phase 3 final rules are emissions standards new vehicles must meet. The regulations apply to the manufacturers of on-highway heavy-duty trucks. Reductions in emissions required under this rulemaking do not start for day cabs until MY 2028. As of MY 2028, manufacturers must reduce GHG emissions across their day cab offerings by 8 percent. That increases annually until 2032, by which time the manufacturers must decrease GHG across their day cab offerings by 40 percent. Sleeper cab tractors have a delayed timeline.

CARB

CARB regulates air emissions in California. It has several long-standing programs in place and three newer programs.

Advanced Clean Truck (ACT): Under this rule, manufacturers must sell a specific percentage of zero-emission vehicles (ZEVs) to be able to sell vehicles in California. Other states are or will be adopting regulations similar to CARB’s ACT.

Advanced Clean Fleet (ACF): Under this rule, state and local government fleets must register their California fleet (vehicles used in California) in CARB’s TRUCRS system. This program requires covered fleets to begin replacing the internal combustion engine (ICE) units used in their California fleet with ZEVs.

Clean Truck Check (also known as the HD I/M regulations): This program requires all non-gasoline powered ICE vehicles that operate in California with a GVWR of 14,001 pounds or more to be registered in CARB’s Clean Truck Check–Vehicle Inspection System (or CTC-VIS) database. Part of registering includes paying a per-vehicle annual compliance fee ($30 in 2023 and 2024). This program also requires vehicle owners or operators to upload onboard diagnostic (OBD) downloads twice a year to CARB, proving that the vehicle is operating within its designed emissions parameters. The OBD download/upload must be done by a CARB-licensed HD I/M tester. Becoming a licensed tester involves taking a CARB training class, passing the final exam, and acquiring the approved equipment.

Truck and Bus regulation: This requires all diesel-powered vehicles with a GVWR of 14,001 pounds to have a MY 2010 or newer engine.

Greenhouse Gas Reduction: This program requires van-type trailers that are over 50 feet in length and the tractors pulling them to have full aerodynamics and low rolling resistance tires.

Drayage Truck regulation: All trucks that operate into, out of, and inside of rail ramps and ports (called drayage trucks) must be registered in the CARB Drayage Truck database and be equipped with a 2010 or newer engine. These trucks are also subject to ACF requirements.

Periodic Smoke Inspection Program (PSIP): This regulation requires fleet owners/operators to have their California-based diesel-powered vehicles with a GVWR of 6,001 pounds or more undergo an annual smoke opacity test once the vehicle reaches four years old (based on model year). This program will remain in place until the Clean Truck Check program is fully implemented in 2025.

Transport Refrigeration Unit (TRU) regulations: To operate in California, a diesel-powered TRU must meet the ULETRU emissions standards, be registered in CARB’s ARBER database, and display an ARB-assigned ID number. TRUs from MY 2023 and newer must meet the next round of PM standards and use Lower Global Warming Refrigerant. Fleets that use truck-mounted reefers (TRUs on straight trucks) must begin transitioning away from diesel reefers and to zero-emission reefers.

CA Electric Vehicle Charging Infrastructure

The California Electric Infrastructure Charging Station Program (CTIP), also known as the Clean Transportation Incentive Program, is a state-funded initiative in California. It provides financial incentives to businesses, government agencies, and individuals to install and operate EV charging stations. The goal of this program is to accelerate the adoption of EVs by making it easier and more affordable for people to charge their vehicles.

The Electric Vehicle Supply Equipment (EVSE or EV Charging Station) Standards Regulation, which implements the Electric Vehicle Charging Stations Open Access Act, sets the requirements for public EV charging stations.

The program ensures that all locations of public EV chargers:

• Can be found through mapping tools,
• Post the costs associated with charging and parking,
• Don’t require a membership to use, and
• Provide multiple payment methods.

EVSE labeling requirements include the following:

• If the EVSE requires payment for use, the electric vehicle service provider (EVSP) must disclose the applicable information at the point of sale:
  • A fee for use of the parking space;
  • A nonmember plug-in fee from the EVSP;
  • The price to refuel in U.S. dollars per kilowatt-hour or megajoule;
  • Any potential changes in the price to refuel, in U.S. dollars per kilowatt-hour or megajoule, due to variable pricing (which may be specified as a range of prices); and
  • Any other fees charged for a refueling session.
• The EVSE must have a credit card reader device physically located on either the EVSE or a kiosk used to service the EVSE..
• The EVSP must provide and display a toll-free number on each EVSE or kiosk used to service that EVSE that allows users to initiate a charging session and submit payment at any time that the EVSE is operational and publicly available.
• The EVSP may not require a subscription or membership to initiate a charging session for an EVSE subject to this section.

About the regulations

On July 10, 2023, a new law was passed called Senate Bill 123 (SB 123). This law made some changes to an earlier law, SB 454, also known as the Electric Vehicle Charging Stations Open Access Act.

It aligns the requirements of the EVSE Standards Regulation with the federal funding requirements of the National Electric Vehicle Infrastructure (NEVI) Program, which was set up in 2022. In addition, SB 123 allows the California Energy Commission (CEC) to create a new rule that will replace the current rule adopted by CARB. Until the CEC sets a new regulation, SB 123 gives CARB the power to change and enforce the rule in line with the new law.

The new SB 123 law took effect shortly after it became mandatory for new Level 2 AC chargers in California to have an EMV chip reader. From now on, CARB will make sure that the payment hardware requirements described in SB 123 are met. For instance, if any Level 2 charging stations were installed after July 1, 2023, without an EMV chip reader required by the current EVSE Standards Regulation, CARB won’t enforce the chip reader requirement for those stations because SB 123 doesn’t require it.

SB 123 is the law and takes precedence over CARB's EVSE Standards Regulation. CARB is currently looking into any other impacts the new law might have on the current EVSE Standards Regulation and may make changes to the EVSE Standards Regulation in the future for more clarity until the CEC sets a new rule.

CA Enforcement of Clean Truck Check HD I/M Regulation

• California’s Clean Truck Check program combines periodic vehicle testing requirements, other emissions monitoring techniques, and expanded enforcement strategies to identify vehicles in need of emissions-related repairs and ensure any needed repairs are performed.
• Clean Truck Check applies to nearly all diesel and alternative fuel heavy-duty vehicles with a gross vehicle weight rating (GVWR) of over 14,000 pounds that operate on California public roads, including both in-state and out-of-state vehicles.

The California Air Resources Board's (CARB's) enforcement of the Clean Truck Check program (originally known as the Heavy-Duty Inspection and Maintenance regulation, or HD I/M, regulation) began in January 2023. The program is intended to:

• Ensure that polluting, poorly maintained heavy-duty vehicles operating in California are quickly identified and repaired; and
• Promote a level playing field for businesses that operate compliant vehicles.

The Clean Truck Check (CTC) program applies to nearly all diesel and alternative fuel trucks and buses with a GVWR over 14,000 pounds operating on-road in California, including:

• Out-of-state and out-of-country vehicles,
• California-registered motorhomes, and
• Agricultural vehicles.

Owners of covered vehicles are required to:

• Report vehicles in the Clean Truck Check–Vehicle Inspection System (CTC-VIS),
• Pay the annual compliance fee, and
• Submit passing emissions by the applicable deadline.

Vehicle owners, operators, freight contractors, seaports, and railyards may become engaged in enforcement actions as a result of inspections, tests, or audits of vehicles, engines, and records.

Potential enforcement actions

Compliance with the regulation prior to enforcement can help avoid enforcement actions, which may include:

• Vehicle registration holds;
• Citations, penalties, or fines; and
• Possible public posting of settlements.

CA Department of Motor Vehicle registration holds are automatically placed on vehicles that are not compliant with CTC requirements.

Vehicles found to be in violation of this regulation are subject to removal from service by the Department of the California Highway Patrol if requested by a CARB inspector and if one or more unresolved citations issued under the program (13 Cal. Code Regs. Section 2198.2(b)(1)) exist at the time of inspection.

Any violation of the requirements may result in citations and penalties. The registered owner, vehicle operator, freight contractor, or other entity that receives a citation will have 45 calendar days (75 calendar days for owners of agricultural vehicles) to submit the applicable demonstration of compliance and any applicable penalties.

Steps to compliance

The CTC program requires all non-gasoline-powered vehicles that operate in California with a GVWR of 14,001 pounds or more to be registered in CARB’s CTC-VIS database. Part of registering includes paying a per-vehicle annual compliance fee.

This program also requires vehicle owners or operators to upload onboard diagnostic (OBD) data to CARB, proving that the vehicle is operating within its designed emissions parameters. The submission due dates are based on:

• The vehicle's plate expiration date if registered/plated in California, or
• The last digit of the vehicle identification number (or VIN) if registered/plated in another state.

In addition to routine testing and reporting, the owner of a vehicle passing through a roadside emissions monitoring device that meets at least one of the criteria specified in Section 2196.5(a) will receive a Notice to Submit to Testing. The owner will have 30 calendar days to submit a demonstration of compliance (specified in Section 2198.2(f)).

Failure to provide the demonstration of compliance by the due date may result in a violation.

Freight contractors, brokers, and freight facilities

The regulation requires freight contractors, brokers, and certain freight facilities to verify fleet compliance prior to doing business with companies or allowing them onto their property.

Brokers and freight contractors, including shippers, receivers, carriers, or governmental agencies, are also required to obtain copies of compliance documentation and maintain records of contracts with those they do business with in California.

Freight contractors must:

• Only contract with compliant vehicles or fleets, and
• Comply with applicable recordkeeping requirements.

Brokers:

• May only arrange transportation within California through motor carriers with compliant vehicles or fleets, and
• Must comply with the recordkeeping requirements.

CARB staff and peace officers have the right to enter freight contractor and broker facilities or sites (or request information) to verify compliance with the CTC recordkeeping requirements.

CA Enforcement Policy & Reports

• The CARB enforcement program is designed to deter noncompliance and to bring into compliance regulated entities that have not met regulatory requirements.
• To resolve violations, CARB uses civil litigation, administrative penalties, and criminal prosecution.

The California Air Resources Board (CARB) enforcement program is designed to deter noncompliance and to bring into compliance regulated entities that have not met CARB’s regulatory requirements.

CARB’s enforcement program:

• Identifies, assesses, and resolves violations; and
• Strives to ensure fair and consistent treatment of each responsible party when applying the laws and regulations to each case.

To resolve violations, CARB uses three types of legal processes:

• Civil litigation: In cases where a mutual settlement cannot be reached, CARB may refer the matter to the Attorney General for civil litigation. As part of the civil process, CARB can obtain a court order or injunction to stop ongoing violations.
• Administrative penalties: CARB has the authority to seek administrative penalties for some violations. In this process, administrative hearings are conducted by administrative law judges using CARB’s administrative hearing procedures.
• Criminal prosecution: In some cases, CARB may identify potential criminal violations. In those instances, the case may be referred to the Attorney General, a District Attorney, or other prosecutors for criminal prosecution.

To ensure fair and consistent treatment of each responsible party when applying the laws and regulations to each case, the CARB enforcement process includes several steps:

• Identify a potential violation. CARB learns about potential violations through inspections, tips from the public, data analysis, referrals from other agencies, mandatory emissions reporting, and voluntary disclosure.
• Evaluate relevant information. Enforcement staff evaluates the information collected to determine violations of requirements. When more information is needed, CARB works with the responsible party to obtain information to identify and assess potential violations.
• Notify the responsible party. CARB may issue a citation, notice of violation, or equivalent document when the evidence is sufficient and a violation could be proven in court. CARB may also initiate a vehicle registration hold through the Department of Motor Vehicles (DMV). Once issued, a registration hold precludes a vehicle from being registered until the violation is cleared.
• Discuss/negotiate the violation with the responsible party. The responsible party has the opportunity to provide evidence to prove a violation did not occur. The discussion often becomes the negotiation between CARB and the responsible party that leads to a mutual settlement and case resolution.

Penalties

A key component of the settlement process is the determination of an appropriate penalty. Penalties are designed to:

• Remove any economic benefit a responsible party obtained through noncompliance, and
• Deter future violations across the industry.

While maximum penalties are established by statute, CARB measures the severity of the violation by considering all relevant circumstances, including the eight statutory factors, together with general considerations that apply to all penalty determinations.

When imposing penalties, CARB considers the following factors:

• The extent of harm to public health, safety, and welfare caused by the violation;
• The nature and persistence of the violation, including the magnitude of the excess emissions;
• The compliance history of the defendant, including the frequency of past violations;
• The preventative efforts taken by the defendant, including the record of maintenance and any program to ensure compliance;
• The innovative nature and the magnitude of the effort required to comply as well as the accuracy, reproducibility, and repeatability of the available test methods;
• The efforts of the defendant to attain, or provide for, compliance prior to the violation;
• The cooperation of the defendant during the investigation and any action taken by the defendant, including the nature, extent, and time of response of any action taken to mitigate the violation; and
• The financial burden to the defendant.

Maximum penalties are adjusted annually based on the California Consumer Price Index (California CPI). Each year, the CARB Enforcement Division publishes a memo documenting the changes to the California CPI and the resultant adjusted maximum penalties.

Public enforcement reports

CARB’s Enforcement Data Portal highlights CARB's enforcement efforts across the state, summarizes recently closed cases, and reports detailed statistics about enforcement-related program activities.

CA Federal Clean Air Act - Title V operating permits

Title V of the federal Clean Air Act (CAA) creates an operating permits program that’s implemented by the states.

California air districts, which the California Health and Safety Code authorized to issue stationary source permits, were required to develop and submit to the U.S. Environmental Protection Agency (U.S. EPA) operating permit programs by November 15, 1993. The California Air Resources Board (or CARB) consulted with the California Air Pollution Control Officers Association (or CAPCOA) Title V Task Force to develop a model Title V operating permit program and rule. Many California districts use the model program and rule as the basis for the Title V operating permit programs.

Permit applications

In general, the sources that must submit Title V operating permit applications include:

• Any "major source" covered by the CAA’s general definitions,
• Any "affected source" subject to CAA Title IV’s acid rain requirements,
• Any solid waste incinerator subject to CAA Section 129(e), or
• Any source in a source category designated by U.S. EPA rule.

Owners or operators of sources required to obtain Title V operating permits had to prepare and submit applications within one year after U.S. EPA approved the state/district program. However, many California districts required certain sources to apply within three or six months of program approval.

The permit applications contained:

• Descriptions of emissions points, emissions rates, and other emissions-related information as required by the district;
• A description (or citation) of all applicable federal air pollution control requirements, including test methods to determine compliance;
• Any exemptions from federal requirements;
• A compliance plan for all sources;
• Proposed methods for certifying compliance and a statement of the source's compliance status;
• A certification statement; and
• Other information.

CA Heavy-Duty In-Use Compliance Program

The Heavy-Duty In-Use Compliance Program (or HDIUC) is intended to determine if engine families operating on the roadways in California are meeting the emissions standards they were designed to meet. As an example, if the vehicle has a model year (MY) 2020 engine, the emissions testing under this program is done to verify the vehicle is still in compliance with the emissions standards applicable to a MY 2020 engine.

Participation in this program is voluntary. Vehicles and companies are selected at random. If selected, the company will be contacted by CARB, and details about the testing process and participation will be discussed.

The testing process involves:

• Inspecting the emissions components on the vehicle (to verify they have not been altered or tampered with),
• Downloading onboard diagnostic (OBD) data (to confirm the engine is operating as designed), and
• Fitting the vehicle with a portable emission measurement system (PEMS).

The vehicle is then operated on routes used by large freight-carrying trucks. The data from the PEMS is then collected and used to determine if the engine was operating within the appropriate emissions standards. After several vehicles with engines from the same engine family have been tested, CARB will determine if the engine family is meeting the applicable emissions standards.

If a family of engines is found to be noncompliant, CARB will work with the manufacturer to correct the discovered issues. Vehicle owners will then receive a recall notice, so vehicles with that engine family can be repaired (at no cost to the owners) and brought back into compliance.

This program is separate from the similarly named Heavy-Duty Vehicle Inspection Program (HDVIP). The HDVIP is a roadside inspection program that determines if a specific vehicle is in compliance with the applicable emissions standards. When a vehicle is selected for an inspection under the HDVIP, participation is mandatory. Vehicles are normally selected for a roadside emissions inspection under the HDVIP due to evidence of possible emissions violations (such as discharging black soot in the exhaust).

CA Onboard Diagnostic (OBD) Program

The California Air Resources Board (CARB) Onboard Diagnostic Program and associate regulations require the onboard diagnostic (OBD) system on a vehicle to meet specific performance standards, collect specific data, be fully functional, and not be tampered with. The U.S. Environmental Protection Agency (or U.S. EPA) has similar regulations at the federal level.

The OBD system on a vehicle continuously monitors the vehicle, engine, and emissions system, watching for malfunctions. When one occurs, a trouble code is created and stored in the OBD’s memory, and the driver is alerted via a malfunction indicator lamp (MIL).

Some trouble codes are temporary (also known as pending). In these situations, the OBD is monitoring the situation to see if the malfunction is real and if it continues. These codes can be cleared by a technician if the malfunction is no longer present.

Other codes are permanent codes, and these can only be corrected by addressing the issue that created the code.

Under the applicable CARB and federal regulations, tampering with the OBD to alter the engine performance in such a way that emissions are affected is not allowed. Also, any tampering that affects the emissions system or how trouble codes are collected, stored, and presented is not allowed.

The OBD system plays a key role in emissions testing in many states, including California. Under the Clean Truck Check program, a vehicle owner must download the OBD data from the vehicle and upload it to the CARB Clean Truck Check–Vehicle Inspection System (or CTC-VIS) database twice a year. Other states also use the OBD to verify emissions compliance, rather than doing the traditional smoke opacity testing (also referred to as the tailpipe smog check).

CA Tractor-Trailer Greenhouse Gas Regulation

The California Air Resources Board (CARB) Tractor-Trailer Greenhouse Gas (GHG) Regulation requires 53-foot-or-longer box-type trailers and the tractors pulling them to be equipped with aerodynamic technologies and low rolling resistance tires when operating on California highways.

The intention of this regulation is to reduce overall emissions, including GHGs, by improving fuel mileage (less fuel burned means less emissions generated). The regulation applies to any tractor-trailer combination that includes a box-type trailer (dry van or van-type refrigerated trailer) that is 53 feet or more in length. Specific regulatory requirements include the following:

• Trailers covered by this regulation must be equipped with:
  • Aerodynamic equipment that improves the fuel mileage, and
  • Low rolling resistance tires.
• Sleeper-berth-equipped tractors that pull covered trailers on a California highway must be equipped with:
  • Full aerodynamics meeting the U.S. Environmental Protection Agency (or U.S. EPA) SmartWay standards, and
  • Low rolling resistance tires.
• Day-cab tractors that pull covered trailers on a California highway must be equipped with low rolling resistance tires.

There are exemptions available for short-haul, local-haul, and storage trailers. To qualify as short-haul or local-haul trailer, the trailer must operate entirely within 100 miles of its normal base of operations. To use any of the exemptions, the carrier must register the trailer in the Tractor-Trailer GHG Portal (Trailer Reporting) system.

CA Zero-Emission Vehicle Fleet program

The California Air Resources Board (CARB) Zero-Emission Vehicle Fleet program is California’s overall plan to transition the vehicle fleets in use in California to zero-emission vehicles (ZEVs).

There are two programs that are part of the Zero-Emission Vehicle Fleet program that affect motor carriers: the Advanced Clean Trucks (ACT) and Advanced Clean Fleet (ACF) regulations.

Under the ACT rule, manufacturers must sell a specific percentage of ZEVs to be able to sell vehicles in California. Note that many other states are or will be adopting regulations similar to CARB’s ACT.

Under the ACF regulation, state and local government fleets must transition to ZEVs. The transition and timeline will depend on the type of fleet and the type of vehicles the fleet operates.