California, Don’t Put the Brakes on Cleaner Diesel Trucks

, , research and deputy director, Clean Vehicles | April 22, 2014, 4:55 pm EDT
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California’s standards to reduce harmful diesel pollution from trucks and buses combined with a new generation of emission-control devices are delivering benefits to the state’s air quality and public health. Recent years have seen significant reductions in smog-forming emissions and particulate matter from these heavy duty vehicles — a leading source of diesel pollution in the state. To stay on track in meeting air quality standards and reducing adverse health impacts, California needs to maintain a strong diesel Truck and Bus Regulation.

By PRA (Own work) [CC-BY-SA-3.0 (], via Wikimedia Commons

By PRA (Own work) [CC-BY-SA-3.0 (], via Wikimedia Commons

Cleaner diesel engines and advanced emission controls are reducing emissions

As a result of California and Federal regulations, starting in 2007, new diesel trucks started being sold with filters that reduce particulate matter 90 percent or more as compared to an engine without a filter. In 2010, these standards were strengthened and additional emissions controls to reduce ozone-causing nitrogen oxides by 90 percent were added to new trucks as well. However, the standards driving these advances in emission controls only apply to new vehicles.

Diesel engines are notorious for their durability; diesel powered tractor-trailers often exceed more than a million miles of driving over the life the vehicle. As a result, diesel trucks tend to stay on the road for a long time — too long for new engine standards alone to meet federal health-based air quality standard deadlines especially in Los Angeles area and the Central Valley of California. And communities most impacted by truck pollution — located near freeways, rail yards, ports and warehouse districts — continue to suffer elevated health risks without addressing pollution from older engines.  These risks have been well documented in health risk assessments carried out for the state’s major rail yards, which show significantly elevated cancer risks near sources of diesel pollution.

California’s Diesel Risk Reduction Program is working

To accelerate the health benefits possible with new emission-control technologies, the Air Resources Board adopted a series of standards compelling owners of diesel trucks and buses currently being operated without these emission controls to clean up their vehicles, with the goal of reducing cancer risk from exposure to diesel particulate emissions by 85 percent by 2020. The most significant of these standards is the Truck and Bus regulation. Finalized in 2008, the rule applies to most heavy-duty diesel trucks and buses that travel California’s roads and highways. This standard requires trucks without modern emissions controls to eventually be upgraded by 2023.

According to estimates by the Air Resources Board, in 2010 diesel trucks emitted over 18 tons of particulate matter per day in California. These emissions have dropped by more than half and by the end of 2014, this regulation to clean up diesel trucks will have prevented 2,700 tons of diesel particulate matter from polluting the air.

Estimated reduction in diesel particulate matter as a result of California's Truck and Bus Rule. Source:  ARB presentation to the board in October 2013.

Estimated reduction in diesel particulate matter as a result of California’s Truck and Bus Rule. Source: ARB presentation to the board in October 2013.

Investments in cleaner trucks pay big dividends

The cost of air pollution is staggering. In the Central Valley and Southern California alone, researchers have estimated that the economic cost of living with polluted air exceeds $28 billion annually. These costs are the result of increased asthma attacks, acute bronchitis in children, heart and lung disease, cancer, more frequent emergency room visits, and lost productivity from school and work absences.

Cleaning up older trucks makes public health and economic sense. The economic savings in avoided health costs and lost work and school days from illness are estimated to be nine times higher than the money invested in equipment upgrades required under the standards. Fully implementing the diesel truck and bus regulation is expected to deliver $48 to $68 billion in economic benefits, and avoid an estimated 3,500 premature deaths by 2025.

Keeping California’s diesel clean–up efforts on track

Over the past several years, millions of dollars in state grants and loans have helped ease the transition to cleaner trucks. In addition, thousands of California truck operators have invested their own funds in emissions upgrades or purchasing newer trucks. These investments are delivering cleaner air. For example, researchers from UC Berkeley measured a 50 percent reduction in diesel soot and a 40 percent drop in smog-forming nitrogen oxide emissions near the Port of Oakland soon after the emission control program for port trucks went into effect in 2010.

The Air Resources Board is considering amendments to the truck and bus rule on April 24. These amendments would provide additional time for thousands of trucks to comply with the standards, delaying some emission reductions. The Air Board should limit any changes to the standards both to ensure continued progress in cleaning California’s air and to recognize the substantial investment that many businesses have already made to reduce the harmful emissions from their diesel trucks.

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  • Clean diesel is a success story in California. This CARB Board decision on the Truck and Bus rule may be controversial to some, but it is not a technology issue nor an options issue; there are plenty of both to go around.

    For those who want to stick with and upgrade existing truck engines, there are well over 40 level 3 verified and effective retrofit device solutions available for trucks. Properly installed and maintained, these will cut emissions of particulates by 85 percent.

    Investing in new technology has significant advantages in the form of saving fuel as well as having near zero emissions. The most recent registration data shows that more truckers are embracing the new generation of clean diesel technology than ever before – as of the end of 2013, 25 percent of all CA registered trucks Class 3-8 are 2007 and newer with about 10 percent 2010 and newer. The new engines deliver not only near-zero emissions, but also fuel savings and other advantages- ones that should especially appeal to fleets.

    Everyone in the state has an investment in clean diesel technology – from the truckers and manufacturers to the citizens and communities that depend on the delivery of goods and services, and the Air Resources Board itself.