When we see photos of brown smog in Beijing and New Delhi, it’s easy to forget that cities in the United States once had similar problems. However, through stricter emission standards, the advent of new technologies from automakers and a greater reliance on cleaner sources of energy like compressed natural gas, American cities have cleaned up their act so that today they serve as a model for urban centers in the developing world.

By 1960 perhaps no U.S. city was more notorious for its air pollution than Los Angeles. Ironically, LA’s problems started because of its reputation for fresh air. In the early 1900s savvy real estate speculators touted the city as a utopia of sunshine and healthy ocean breezes. Their pitch worked beyond even their wildest dreams, transforming LA from a modest city of around 100,000 people in 1900 to a full-fledged metropolis of almost 2.5 million by 1960 and about 3.8 million people today.

The number of cars also surged. In 1920 a mere 160,000 cars were registered in the city, but by 1950 there were nearly two million cars in Los Angeles County. Emissions from all those cars helped make smog LA’s new trademark.

The growth the city experienced throughout the 20th century is now being recreated in the 21st century by rapidly expanding cities across Asia and Africa. In 1950 only 30 percent of the world’s population was urban, but the United Nations predicts more than 65 percent of people will live in cities by 2050, with nearly 90 percent of the increase occurring in Africa and Asia. ExxonMobil’s latest Outlook for Energy report highlights that continuing urbanization trend, especially in China and India, stating that growing consumption by an expanding urban middle class will play a part in driving much of the increase in energy demand over the coming decades.

Fortunately, Los Angeles also provides a model for how cities can combat air pollution. As early as 1963 California required cars to have newly developed emission control devices. As the technology improved with, among other things, the introduction in 1975 of catalytic converters, so too did LA’s air quality. However, while emission controls continue to play an important role in fighting urban air pollution, technological improvements in the types of fuels used in transportation may play a critical role to clean up the air in the megacities of the 21st century.

Compressed natural gas (CNG) in particular has been adopted as an important element in reducing urban air pollution. Natural gas vehicles emit up to 21 percent fewer greenhouse gas emissions than comparable gasoline and diesel vehicles.

In fact, Los Angeles is arguably the global leader in CNG vehicles. The LA metro area has the greatest concentration of CNG fueling stations in the state of California, which in turn has the most CNG fueling stations in the United States. The city has a fleet of over 2,000 buses that run solely on CNG; the fleet has driven over a billion miles. Not coincidentally, LA’s average overall air quality is much improved since the adoption of new technologies and fuels like CNG, suggesting that in the future fuels like natural gas could play a major role in cleaning up the air of new megacities in the developing world.

What is Compressed Natural Gas (CNG)?

Taking natural gas and compressing it down to less than one percent of its naturally occurring volume makes compressed natural gas, or CNG, a cleaner and less expensive alternative to other conventional fuels.

In its Outlook for Energy report ExxonMobil predicts that the cost savings associated with CNG is already making the fuel a popular choice for heavy duty vehicles like transit buses. The report notes that while equipping a truck to run on CNG in the United States can cost about $30,000 more than a standard diesel vehicle, a lower price for CNG can help operators make their initial investment back.

Of course, the environmental advantages also make CNG attractive, especially for use in urban public transportation fleets. Compared to gasoline, CNG not only produces less CO2, but also pollutants like nitrogen oxides that are an important component of smog.


  • icon/text-size
You May Also Like

Explore More

Five trends in creating energy-efficient cities
The power of algae