Though efforts to curb vehicle pollution have made an impact, much more remains to be done. Consider:

• Even if every vehicle on the road in 2009 met federal Tier 2 emission standards, the U.S. vehicle fleet would still emit 500,000 tons of smog-forming pollution every year.
• In 2020, when more than 75 percent of vehicles on the road will meet Tier 2 emission standards, passenger vehicles will still generate emissions that represent a cancer risk equivalent to 350,000 tons of benzene released into the atmosphere every year.
• Only four nations in the world produce more heat-trapping carbon dioxide than the U.S. vehicle fleet. This pollution is expected to cause worse smog, an increase in asthma-triggering pollens and molds, and a substantial rise in the number of heat-related illnesses and deaths.
• Diesel-powered vehicles account for nearly half of all nitrogen oxides and more than two-thirds of all particulate matter (soot) produced by the U.S. transportation sector. Soot irritates the eyes and nose and aggravates respiratory problems including asthma, which afflicts 13 million Americans.

This section offers detailed information on the current and projected consequences of vehicle pollution on public health and global warming, and what that might mean for you, your family, and the planet.

Light Trucks and Air Pollution

Pollution from light trucks is growing rapidly, with minivans, pickups, and sport utility vehicles (SUVs) now accounting for one of every two new vehicles purchased. Responding to the consensus that tailpipe standards were long overdue in catching up with market trends and engineering capabilities, both California regulators and the EPA recently adopted new rules requiring light trucks to become as clean as cars over the next seven to nine years. This briefing describes the air quality challenges and engineering solutions that prompted the new regulations.

The Clean Air Challenge

Despite decades of air pollution control efforts, at least 92 million Americans still live in areas with chronic smog problems. The EPA predicts that by the year 2010, even with the benefit of current and anticipated control programs, more than 93 million people will live in areas that violate health standards for ozone (urban smog), and more than 55 million Americans will suffer from unhealthy levels of fine particle pollution. This pollution is especially harmful to children and senior citizens.

While new cars and light trucks emit about 90 percent fewer pollutants than three decades ago, total vehicle miles driven have more than doubled since 1970 and are expected to increase another 25 percent by 2010. The emission reductions from individual vehicles have not adequately kept pace with the increase in miles driven and the market trend toward more polluting light trucks. As a result, cars and light trucks are still the largest single source of air pollution, accounting for one-quarter of emissions of smog-forming pollutants nationwide.

History of Light-Truck Emission Loopholes

Current federal tailpipe standards allow sport-utility vehicles and trucks to pollute over twice as much as the average new car. In 2001, this gap will more than double under the National Low Emission Vehicle (NLEV) program as cars become cleaner, while the larger light trucks continue to receive special pollution exemptions.

Pollution breaks were originally granted to light trucks because they were used primarily for hauling heavy cargo, they comprised a small share of the new vehicle market, and the state of engine and catalyst technologies were not advanced enough to achieve car-equivalent emissions. However, the situation has changed dramatically on all of these points in recent years.

An Air Pollution Liability

Today most light trucks are used as basic transportation by their owners, while the largest truck categories--those most likely to be used as work vehicles--comprise only one-third of the light truck market. In fact, a study by the former American Automobile Manufacturers Association found that only 15 percent of all sport-utility vehicles are ever used for towing. Light trucks are the new passenger cars of choice, representing half of new vehicle sales.

This trend toward light trucks has resulted in significant erosion in the benefits of government efforts to reduce air pollution from motor vehicles. UCS analysis shows that the light-truck loopholes, coupled with booming sales of sport-utility vehicles, have resulted in an additional 5,000 tons per day of smog-forming pollutants in our air during the summer smog season. This is equivalent to the pollution from 40 million cars, five times the number of cars sold last year.

Meeting the Same Standards as Cars

New emission standards must account for the fact that some light trucks are used to tow heavy loads. Fortunately, modern technology enables light trucks to meet car-equivalent emission standards while retaining their hauling capabilities, due to dramatic improvements in the technology to control air pollution from engines and the durability and efficiency of catalytic converters. Several studies have demonstrated that achieving car-equivalent tailpipe standards on trucks (the so-called Tier 2 standards) is technically feasible and will cost much less than other emission-reduction measures.

Under the California test program, it took less than a year to modify a Ford Expedition--which falls into the heaviest light-truck emission category--to meet the proposed Tier 2 standards. The engineers reduced the pollution level by 90 percent from the emissions standards by simply reprogramming the air/fuel system and adding a more durable catalyst. Furthermore, they subjected the catalyst system to rigorous testing under a "worst case" drive cycle that simulated heavy towing of up to 14,000 pounds, representing use on a "work truck."

The total added costs of these improvements were estimated to be about $200 per vehicle on a full-size sport-utility vehicle. This $200 for improved pollution-control equipment is just a fraction of the price paid by consumers--or of the profit margin enjoyed by automakers--for most sport-utility vehicles. This is one of the cheapest air pollution mitigation investments that can be made.

Real-World Emissions

This is the executive summary from the 1997 UCS report "Are Cars Still a Problem?: Real-World Emission Reductions from Passenger Vehicles Over the Past 30 Years"

In 1996, auto and oil industry groups claimed that modern cars emit 96 percent less pollution than 1960s-era cars built before emissions were regulated. These claims were misleading. In fact, 30 years of motor-vehicle pollution control regulations have reduced pollution from the entire US passenger vehicle fleet far less than one would expect. Here's why:

• A significant gap exists between emission standards and what cars emit in the real world. The primary sources of these excess real-world emissions are malfunctioning emission control equipment, aggressive driving behavior, and air conditioning operation. None of these "off-cycle" emissions are captured in the regulatory test cycle.
• Total miles driven by all passenger vehicles in the US (cars and light trucks) increased 2.7 times between 1965 and 1995, offsetting substantial amounts of the pollution reductions achieved on a per vehicle basis.
• The market share of light trucks (pickups, minivans, and SUVs) increased from 15% to 40% between 1970 and 1995. These light trucks have less stringent emission standards than passenger cars, especially for nitrogen oxides. In addition, the number of miles light trucks drive has increased at a much faster rate than the number of miles cars drive: 5.9 times for light trucks versus 2.2 times for cars.

Key Findings

• The claim that an individual modern car is 96% cleaner for carbon monoxide and hydrocarbons and 90% cleaner for nitrogen oxides than its precontrol-era (1960s) counterpart is overstated. Over its lifetime, the average emission rate for a car is much higher than its emission standard. A modern car will likely emit 4 times more carbon monoxide, 2 times more hydrocarbons, and 3 times more nitrogen oxides (Figure 1).
• For the entire US passenger vehicle fleet, emissions reductions have been considerably more modest or nonexistent. While emissions of hydrocarbons have been reduced by about two-thirds, emissions of carbon monoxide have dropped only a third, and nitrogen oxide emissions have actually increased more than a fifth over the past 30 years (Figure 2).
• The light truck fleet's share of US passenger vehicle emissions has increased by 1.7 times for carbon monoxide, 2.3 times for hydrocarbons, and 1.3 times for nitrogen oxides over the past 30 years. For the combined inventory of smog-forming pollutants (hydrocarbons and nitrogen oxides), the share contributed by the light truck fleet has doubled.
• The passenger vehicle fleet is still the largest single source of carbon monoxide and smog-forming pollutants nationwide. For hydrocarbons and nitrogen oxides separately, it is the second largest source, and its shares of these inventories have not changed appreciably since 1970.

Conclusion

With half of all Americans living in areas that violate national clean air standards, clearly emissions from the passenger vehicle fleet must be reduced. The main strategies that state and federal governments must adopt to reduce pollution from cars and trucks are

• lower emission standards to treat light trucks and cars equally
• implement well-run inspection and maintenance programs
• increase regulatory focus on emission control system durability and off-cycle emissions
• promote the introduction of truly advanced, intrinsically-clean vehicle technologies that have lifetime, real-world zero or near-zero emissions