Newly proposed air quality regulations could dramatically alter the fleet of heavy-duty diesel trucks on California’s roads and highways, including those used to transport farm inputs and harvested agricultural products.

New regulations in development by the State Air Board will require significant and expensive retrofitting of older diesel engines to bring trucks into compliance, including seasonal diesel trucks used to transport harvested almonds and other agricultural commodities to and from the field and processing facilities. It may also impact delivery costs for farm inputs if suppliers pass on the cost of retrofitting their fleets to their customers.

Air Board staff are currently surveying diesel truck operators, including a separate survey for agricultural vehicles, to obtain information about truck ages, mileage, and vehicle use patterns in advance of submitting a formal proposal to the Air Board by mid-2008.

Commodity groups, such as the Almond Board of California, California Grape & Tree Fruit League, and California Cotton Growers and Ginners Association, are working to provide ARB staff with information on heavy-duty diesel trucks within their industries. The Almond Board will be asking its members to provide information in advance of issuing a summary report to ARB. When asked, please take a few minutes to fill out these surveys to ensure your industry is accurately represented.

The new regulations are intended to move the State Air Board toward achieving mandates in the California Diesel Risk Reduction Plan to reduce emissions of diesel particulate matter (

The Air Board also in late September adopted a new State Implementation Plan (SIP) for meeting federal clean air deadlines for ozone reduction under the Clean Air Act. That SIP calls for a 62-ton reduction in NOx from trucks by 2017 in the San Joaquin Valley and a 76-ton reduction by 2014 in the South Coast.

To achieve this, under the current proposal, heavy-duty diesel vehicle owners will have to either replace older engines or retrofit them with a Verified Diesel Emission Control Strategy to bring them into emissions compliance.

All on-road heavy-duty diesel vehicles with pre-2007 engines must eventually be brought into compliance through the use of “Best Available Control Technology (BACT)”, such as emissions-reducing filters or exhaust recirculating systems.

The first phase of the current proposal would require trucks with diesel engines built before 1998 to be retrofitted to reduce NOx and particulate matter emissions to the equivalent of a 2007 model-year engine. Truck owners will have until Dec. 31, 2009 to bring pre-1998 vehicles into compliance. Then, engine model years from 1998 to 2002 will have until the end of 2011, and so on, until all trucks with pre-2007 engines are in compliance by Dec. 31, 2013.

A second phase will require truck engines to meet emissions at or below a 2010 model-year engine by Dec. 31, 2020.

It is important that each sector in the ag industry provide input about their use of heavy-duty diesel on-road vehicles and what impacts proposed new regulations might have on the industry. ARB may consider the time of use in determining when a retrofit is needed for seasonal ag users.