Clean Cars in California
Four Decades of Progress in the Unfinished Battle to Clean Up Our Air

Executive Summary

California’s efforts to reduce air pollution from cars and trucks have made the state’s air cleaner than it has been in decades – and Californians are healthier as a result. Clean car standards have helped cut total automobile air pollution in California by more than 85 percent since 1975, despite rapid growth in population and vehicle travel.

However, many Californians are still exposed to some of the worst air pollution in the United States – contributing to high asthma rates and shortened life spans. Passenger cars and trucks produce nearly 2 million pounds of health-threatening air pollution statewide every day.

To continue progress, state officials should update California’s vehicle emission standards and ensure that they remain strong and effective. Given the size of California’s vehicle population, the state needs to make sure that new cars are as clean as possible – and to encourage auto manufacturers to rapidly commercialize vehicles that produce no pollution whatsoever.

Unhealthy air has been a life-or-death problem facing Californians for decades.

  • During the summer of 1943, a cloud of smog cut visibility in the Los Angeles area to only three blocks. People exposed to the hazy, acrid cloud suffered from eye irritation, respiratory problems, nausea and vomiting. Eventually, scientists recognized that smog was caused by pollution from fossil fuel combustion and gases evaporating from fuels and solvents, reacting together in sunlight.
  • As California’s population grew and more cars were driven more miles each year, the state’s smog problem grew worse. In the 1970s and early 1980s, for example, peak smog levels in the Los Angeles area were routinely five times higher than the state’s current air quality standard. As state population grew, high smog levels expanded to other areas, including the Central Valley and the Inland Empire.
  • Extreme smog levels caused serious harm to public health – including premature death, increased hospital admissions and emergency room visits, more asthma diagnoses and asthma attacks, and more frequent missed school and work days due to respiratory illness.

To protect public health, state officials required auto manufacturers to develop and install new technologies to control emissions from their vehicles.

  • California created the world’s first tailpipe emission standards in 1966. State officials have regularly updated and strengthened the standards over the years, adding evaporative emission standards and requiring increased emission control system durability. In 1990, state officials added a requirement for automakers to develop and market advanced technologies, including “zero-emission vehicles” with superior emission control systems and even new kinds of fuels and engines.
  • These standards forced automakers to innovate. In response to the requirements, automakers invented and refined the catalytic converter – now standard equipment on every gasoline-powered car in the United States and most in the world – and a variety of other enhanced emission control technologies. The standards also spurred automakers to introduce super-clean gasoline-electric hybrid cars – such as the Toyota Prius.

California’s vehicle air pollution standards have been extremely effective. Today’s cars and trucks are much cleaner, and overall vehicle emissions have dramatically declined.

  • A typical new car sold in California in the 1960s produced about one ton of smog-forming pollution for every 100,000 miles of driving. Today, under California’s Clean Car standards, a typical new car is more than 99 percent cleaner, producing about 10 pounds of smog-forming emissions driven over the same distance.
  • Total annual emissions of smog-forming pollution from passenger cars and trucks in California have dropped more than 85 percent since 1975, even as the number of miles driven in the state has more than doubled.
  • California’s Clean Car standards have cleaned up our air without crippling the economy or making cars too expensive. Automakers have tended to overestimate the cost of emission controls by a factor of two to 10.
  • Investments in cleaner air have been worth it. According to the U.S. Environmental Protection Agency, the health benefits of clean air advances achieved since the 1970s exceed the cost of emissions controls by as much as 100 to 1.

Clean car standards have helped to reduce smog levels in major metropolitan areas, including Los Angeles, the San Francisco Bay Area, San Diego, and cities in the Central Valley – improving public health.

  • Since 1980, peak smog levels have dropped by 70 percent in the Los Angeles area; 50 percent in the San Diego area and in the Sacramento Valley; 40 percent in the San Francisco Bay Area; and 33 percent in the San Joaquin Valley.
  • Cleaner air prevents asthma attacks and cancers, reduces the burden of respiratory disease, and saves lives.

Despite the state’s tremendous progress, California still suffers from air that is unhealthy to breathe.

  • California still has the worst smog pollution in the country. All 10 of the most polluted counties nationwide are located in California. Smog levels still exceed state health-based standards for more than one-third of the year in the Los Angeles area and the San Joaquin Valley.
  • Passenger cars and trucks are still an important part of the problem. These vehicles emit nearly 2 million pounds of smog-forming pollution daily across the state – almost 20 percent of total smog-forming emissions.
  • Scientists are also continually uncovering evidence that smog can harm our health at very low levels of exposure. New information may lead to tighter health standards, requiring greater emission reductions.

New technologies can make our cars even cleaner, and cleaner cars are a critical piece of reducing our exposure to unhealthy air. The California Air Resources Board should ensure that the next round of vehicle emission standards are strong and effective.

  • Updated Clean Car standards should ensure that future cars are as clean as possible, requiring all internal combustion engines to meet “Super-Ultra Low Emission Vehicle” performance, with emission control systems durable up to 150,000 miles.
  • The standards should also chart a course for widespread commercialization of next-generation cars with no tailpipes or emissions – such as electric cars.
  • Finally, the standards should facilitate reducing vehicle global warming pollution in accordance with state goals to reduce overall emissions 80 percent below 2005 levels by 2050.