Declaring it the largest environmental investment ever undertaken by a cargo complex to wean itself off diesel dependency, Los Angeles and Long Beach port officials Wednesday unveiled their Clean Air Action Plan update, with a price tag that could reach $14 billion.

The latest installment in a decadelong effort to cut down pollution along the docks, which has already drastically reduced the toxic soup around the mammoth complex, aims to replace dirty-burning trucks and cargo-handling equipment with gear that produces zero, or almost zero, emissions.

Officials didn’t soft sell the price, acknowledging that it will place “an enormous financial burden on the ports and goods-movement industry,” even if government helps foot the bill.

CAAP is the heart of the joint vow made by Los Angeles Mayor Eric Garcetti and Long Beach Mayor Robert Garcia to make the nation’s busiest port complex a nearly no-pollutant zone by 2035.

If the promise is kept, the project will eliminate the region’s largest stationary source of pollution. Diesel emissions have been linked to higher rates of asthma and respiratory problems in communities around the ports, and Gov. Jerry Brown has staked his legacy on fighting climate change in the state.

Here’s how the long-awaited plan aims to work:

The strategy

The bottom line: CAAP would convert the port’s huge truck fleet from diesel to zero-emission fuels, develop and deploy green-burning gear to load and unload ships and assertively grow pollution-cutting programs for port-run vessels and other ships.

The timetable: Last fall’s draft version was broadly scrutinized and subsequently revised, and more review will come quickly. Los Angeles and Long Beach harbor commissions must approve the plan, and a vote is expected in November.

How you can get involved: A new public comment period for the plan extends through Sept. 18, and officials will be holding a public workshop on Aug. 30 at Banning’s Landing Community Center. For more info: www.cleanairactionplan.org.

The price — and how to pay it

The bottom line: Between $7 billion and $14 billion would be spent to rid the ports of machines now powered by fossil fuels.

The breakdown: As much as $8.2 billion would be spent to deploy zero-emissions big-rigs and another $1.03 bullion to deploy near-zero emissions vehicles.

Cargo handling: Green-burning equipment would cost as much as $2.1 billion. The infrastructure to support it? Another $2.2 billion.

At berth: As much as $138 million would be spent to reduce emissions where ships are moored.

Ships: As much as $137 million would pay for incentive programs to reduce emissions produced by cargo craft visiting the ports.

R&D: $22 million would fund research, development and demonstration of new gear.

Who pays for it?: Starting now, port officials are looking for support from the state and federal government.

Gov. Brown and the Democrat-dominated Legislature are likely proponents. But the reception from Washington, D.C., is likely to be a lot chillier. With Donald Trump in the White House, California can no longer rely on the administration for rubber-stamped support of its environmental goals.

Regardless, the plan makes it clear: “Outside of any state and federal funding … these costs will be borne by the ports themselves and private industry.”

How fast?: Officials will need much of the funding within five- to seven years to ensure there is the infrastructure in place to convert to zero emissions beyond that time.

Air — and how to clean it

The bottom line: The plan seeks to cut greenhouse gas emissions and rid the hub of harmful diesel pollutants. Why? In the areas closest to the ports, asthma hospitalization rates among children — who are more sensitive to toxic air — are higher than other parts of Los Angeles. One study suggests freight pollution costs Long Beach and Riverside, where much of the container traffic winds up, about $18 million annually to address asthma and respiratory problems.

The breakdown: Targeted cuts in greenhouse gases are 40 percent below 1990 levels by 2030 — and 80 percent below 1990 levels by 2050. The plan doesn’t create goals to further reduce diesel particulate matter, sulfur oxides or nitrogen oxides beyond those made in its 2010 plan. Instead, it relies on new, clean-burning technology to further slash emissions.

The response: The move is likely to upset environmentalists who wanted to see more aggressive efforts to eliminate the most toxic of pollutants.

“The mayors laid out a bold vision for what they expect. What people are going to look at is, ‘Does this plan live up to this vision?’ ” said Adrian Martinez, an attorney for Earthjustice. “You have to have a way to measure success otherwise it’s another policy plan that could be dismissed at the whim of future harbor commissions,” he said. “Emissions commitments are important.”

Trucks — and what they’ll run on

The bottom line: Since 2006, the clean ports program has focused on cleaning up diesel trucks, a major driver of harmful pollutants. The ports vow to intensify that effort.

The breakdown: Truckers must register their big rigs with the ports to bring loads in and out. Next year, all new trucks that register must meet 2014 emissions standards. The standard will be upped to near-zero emission in 2023 for newly registered trucks. But that leaves thousands of trucks with older engines that belt out pollutants. There are about 16,000 trucks serving the port, and every year about 5 percent — or 800 trucks — in the fleet are new. So, the conversion to cleaner trucks will move at a deliberate pace.

Penalties: In 2035, big-rig drivers not meeting zero-emissions goals at the port must pay a fee.

Waiting: An appointment system for truckers aims to prevent drivers waiting hours for a load to arrive while their idling engines stir up pollutants.

The loophole: Port officials earlier proposed an even more stringent regulation that would have imposed fees and restrictions on all trucks 10 years or older but had to nix the idea because of a concession the Legislature gave the trucking industry.

The industry supported Brown’s $5 billion a year plan to fix crumbling transportation infrastructure by raising fees on vehicles and gas. In exchange, the trucking industry could keep dirtier burning trucks that have 800,000 miles — or up to 18 years of service — without having to worry about testing.

“Without the state moving forward on new requirements,” said Heather Tomley, director of environmental planning at Long Beach’s port, “we are not in a position to accelerate what they have done.”

On the dock — and at the shore

The bottom line: Ports will sink millions of dollars into testing and developing near-zero emissions technology with the hope of bringing to market a new generation of equipment to make the ports run faster and cleaner.

The breakdown: Officials aims to fill the docks with zero-emission terminal equipment by 2030, another goal of the governor.

Rail: Port officials hope to get half of all the containers coming in from Asia and other markets on rail, rather than on truck trailers, to ease congestion on freeways and eliminate some pollution.

Ships: The ports can’t control the fuel burned by ships that bring in cargo. But they will extend the vessel-speed reduction program, which keeps ships from burning excessive amounts of fuel. And ports will continue to encourage shippers to use plug-in technology while along the docks.

The response

From the ports: “A major part of our success is going to be getting as much funding as we can to support this transition,” said Long Beach’s Tomley, who helped put together the plan.

From shippers: “The CAAP puts all its eggs in one basket by unrealistically assuming that nonexistent, nonautomated, zero-emissions electric cargo handling equipment technology will be developed, tested, work as planned and be affordably mass produced to meet the ports’ rigid timelines,” John McLaurin, president of the Pacific Merchant Shipping Association, said in a released statement. “That’s a pretty big assumption with no margin for error and no Plan B if and when something goes wrong.”

From the trucking industry: “It is important to set goals that are reasonable and attainable, and that we don’t saddle an industry that has invested billions of dollars in clean technology with a mandate that is not viable commercially or operationally,” said Weston LaBar, executive director of the Harbor Trucking Association. “There are still many questions regarding zero-emissions truck technology. It is important that the ports ensure the final plan paves a path forward for affordable and efficient movement of cargo through the San Pedro Bay Complex first, and that sustainability is a byproduct of a healthy supply-chain in the region.”

From lawmakers: “Our port can be the global model for clean air, healthy communities and effective operations — that’s why I set a goal for zero emissions trucks and equipment at the Port of L.A. by 2035,” said L.A.’s Garcetti. “The Draft Clean Air Action Plan is a critical first step, and we will continue our work toward a final document that enables us to meet our ambitious goals.”

“The draft CAAP is a positive next step toward our goal of zero emissions and improving efficiency at the Ports of Long Beach and Los Angeles,” said Long Beach’s Garcia. “We will continue to work collaboratively to implement the CAAP’s innovative approaches, ensuring cleaner, greener seaports.”

From environmentalists: “While the ports estimate short-term costs as high as $14 billion for new technologies, the cost of looking into your child’s eyes searching for you to help them breathe cannot be measured in dollars,” said Sylvia Betancourt, a project manager at Long Beach Alliance for Children with Asthma. “Families pay with increased anxiety, health care costs and missed school and work days. If community health and quality of life is truly at the forefront, the ports must go one step further in this document and prioritize investment in zero-emission technologies now.”

Editor’s note: A previous version of this story included an incorrect estimate for the cost of cargo-handling equipment and misspelled John McLaurin’s name.