A disputed regulation from the California Air Resources Board is under heavy fire from the produce industry, and an upcoming release of proposed amendments will tell if any of the bullets hit.

After controversy over the data used to shape the California Air Resources Board’s regulations for diesel truck emissions, the board is pushing things back a little and drafting revised regulations.

Current regulations require diesel trucks in California to be retrofitted with filters that can cost up to $40,000 per truck and replace engines older than 2010 by the year 2023. A new engine runs $50,000 to $150,000, said Kelly McKechnie, government affairs analyst for Western Growers.

The Irvine-based association has been at odds with the regulatory board, arguing that controversies over the emissions estimates and public health data on which the regulations are based undermine the credibility of the regulations, and the board itself.

“I don’t think there is a tremendous amount of confidence in the regulatory process forming this rule or the science beneath it,” said Dave Puglia, senior vice president of government affairs and communications at Western Growers. “Our office is expecting them to adjust the emissions estimates downward. We don’t know how much, and that will be a critical piece of the equation.”

The air resources board is charged with implementing, overseeing and enforcing the regulations. It is expected to release amendments to the rule by the first week of November. In recent weeks, the board scheduled public workshops on the amendments.

“The fresh produce industry relies on trucking to move product from the fields to the cooler, processing facility and to market,” Puglia said. “The cost of trucking would go far higher if you’re mandating replacement of a perfectly good truck made in 2009, forcing it out of service prematurely. And the reality of the produce marketplace is these costs are not going to be borne by the consumer.”

The regulations also create a high marketplace demand for 2010 or newer trucks, driving the price upward, and an artificial glut of used trucks 2009 or older.

Authorized by the Environmental Protection Agency under the Clean Air Act, the regulations set emissions limits on diesel trucks and buses. Those limits are based on studies that link emissions with some premature deaths, but Puglia said researchers involved in the studies are not credible.

As written now, particulate matter reduction requirements start Jan. 1, and vehicle engine replacement requirements to reduce nitrogen oxides start in 2013.

The tiered implementation program requires vehicles to retrofit or replace engines at different stages, requiring all trucks to have a 2010 engine or equivalent by Jan. 1, 2023.

Growers are cut some slack with certain agricultural vehicles, including those used exclusively to transport unprocessed products to the first point of processing, with a delay until 2023. In the original rule, only 1,100 vehicles in the San Joaquin Valley and 2,200 statewide would be considered agricultural vehicles, but McKechnie said that limit would likely be left out of the amended rule.

The air resources board intends to bring the rule before its full board of directors in December.

“We can’t overlook it if California grower-shippers are going to be put at even more of an economic disadvantage than those in other states and countries,” Puglia said. “If you put yourself in the shoes of a buyer, this is one reason you’re going to think about sourcing from somewhere else and not in California.”