Sick of Soot (2004)

Solutions to California's diesel pollution
August 2004
Soot emitted from vehicles is a major health concern for many Californians.

Diesel soot, or particulate matter (PM), is a dangerous pollutant that can penetrate deep into the lungs. People exposed to diesel soot can suffer from severe respiratory and cardiovascular illnesses, chronic bronchitis, cancer, and premature death. California, with the largest population of people and diesel vehicles in the country, is in essence a microcosm of the national health risks of diesel emissions.

Diesel Soot: A California Killer

In 2000, the California Air Resources Board (CARB) estimated that diesel PM was responsible for 70 percent of the state's risk of cancer from airborne toxics (CARB, 2000c). Diesel engines often remain in operation for decades, with the older engines releasing the greatest amount of pollution. In 2004 alone, diesel pollution will cause an estimated 3,000 premature deaths in California—greater than the estimated 2,300 annual homicides in the state.1 In addition, diesel exhaust will cause an estimated 2,700 cases of chronic bronchitis and about 4,400 hospital admissions (including emergency room, or ER, visits) for cardiovascular and respiratory illnesses every year. The cost of these health impacts is $21.5 billion per year.

While Californians in every corner of the state are exposed to diesel pollution, the most densely populated and polluted air basins have the highest number of health problems. Roughly 90 percent of California’s population, and 80 percent of the state’s diesel pollution sources, are found in 5 of the 15 air basins: Sacramento Valley, San Diego, San Francisco Bay Area, San Joaquin Valley, and South Coast. This sets an important example for population centers nationwide.

Diesel Soot Reduction is Cost-Effective

In 2000, CARB developed the Diesel Risk Reduction Plan, which calls for reducing diesel PM 75 percent by 2010 and 85 percent by 2020 (from the base year 2000 level). UCS finds that implementing the Risk Reduction Plan could cut diesel-related health incidences and health costs by more than half from 2004 levels, and reduce cancer risk from exposure to diesel exhaust by 80 percent.

Using financial data from the U.S. Environmental Protection Agency (U.S. EPA, 2003), the Union of Concerned Scientists (UCS) has evaluated the economic impact of these diesel-related health problems and compares the costs to the benefits of reducing diesel pollution. UCS finds that California's plan to reduce diesel pollution, which calls for reducing emissions from engines on the road today, would prevent an estimated 11,000 premature deaths and 16,000 hospital admissions (including ER visits) by 2020. Cutting pollution from existing diesel engines would result in a cumulative savings of $48 billion to $70 billion between 2004 and 2020. This analysis represents a conservative estimate because many potential health and welfare impacts—such as smog-related respiratory problems, increasing asthma rates (especially for children), and damage to agricultural crops and forest habitats—are not quantified.

To meet these goals, the plan calls for stronger emission standards, retrofit regulations, and voluntary incentives such as a statewide clean school bus grant program and the "Moyer Program" which provides funding for diesel equipment owners to replace or rebuild high-polluting diesel engines. But the plan is in jeopardy of falling short of its goals due to regulatory gridlock and a lack of funding. Unless additional action is taken, diesel PM will only be cut about 30 percent by 2010, rather than the 75 percent target.2  

Policy Recommendations

California should fully implement its Diesel Risk Reduction Plan by requiring early retirement of the worst polluting vehicles and advanced pollution control retrofits where possible. Key sectors including ports, ships, trains, construction equipment, agricultural engines, and most highway trucks and buses need to be cleaned up. California’s successful incentive programs should receive sufficient and sustainable funding, rather than struggling every year with reduced budgets. In addition, the Moyer Program should be strengthened by allowing state funds to be used for projects that reduce PM only and by targeting funding to high-risk areas and populations.  

(1) Estimated Health Benefits from $100 million/yr. funding of Moyer Program
Number of homicides is for 2001, based on data from the California Department of Health Services.

(2) UCS's evaluation included the impact of recent diesel cleanup regulations passed by CARB but not yet finalized, federal highway tailpipe standards, and the federal highway nonroad rule passed in May.

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