Scholastic News Online

Scholastic News Online is a free resource with breaking news and highlights from the print magazine.

Available for grades 1-6, Scholastic News magazine brings high-interest current events and nonfiction to millions of classrooms each week.

Additionally, our subscribers have FREE access to Scholastic News Interactive, an exclusive online learning tool featuring digital editions, videos, interactive features, differentiated articles, and much more.

Scientists say chemicals released by motor vehicles, especially cars, caused the smog problem in Los Angeles. (iStockphoto)

Clearer Skies Over Los Angeles

Environmental laws help clean the air in Los Angeles

By Joe Bubar | null null , null

Los Angeles, California, is a city known for having movie stars, warm weather, and very thick smog. Smog is a hazy layer of pollution that hangs in the air. In L.A. and many other cities around the world, smog can be thick enough to darken the sky, make people’s eyes sting, and hurt people’s throats just from breathing.

But these days, people in L.A. are seeing things much more clearly. A recently published study found that the air pollution in the city has decreased even though there are more cars in the city than ever before.

“L.A.'s air has lost a lot of its ‘sting,’ ” says Ilana Pollack, the scientist who led the study. She works for the National Oceanographic and Atmospheric Administration, which monitors water and sky conditions in the United States. Pollack adds that California’s strict laws on motor vehicles have had a lot to do with the good news.


California is often called the “smog capital of the United States.” Fifty years ago, the pollution would sometimes get so bad that schools would have to shut down until the air cleared up.

Scientists at that time found that cars were to blame for the smog. L.A. and its surrounding area have more cars than any other urban area in the world. All these cars can be bad for the environment. Cars release a chemical called peroyxacetyl (per-ok-see-a-SEE-tel) nitrate, also known as PAN. PAN makes eyes sting when too much of it gets in the air.

In 1963, California lawmakers decided to do something about the smog. They passed a law that limited the amount of PAN and other harmful chemicals that cars were allowed to emit (produce, or give off).

In the half century since then, the amount of smog in the air has actually decreased—even though three times as many cars are on the roads in Southern California today as there were 40 years ago. Scientists say the decrease in smog is a sign that the laws have been working.


Los Angeles still has some work to do, though. It remains the worst city in America for ozone pollution.

Along with PAN, ozone is a major chemical found in smog. Chemicals from cars help produce ozone. Though it is good for the Earth when it’s high above the planet, ozone is bad when it’s closer to Earth’s surface. A coating of ozone, called the ozone layer, covers Earth’s atmosphere and blocks dangerous rays of the sun from reaching the planet’s surface. Yet when ozone is too close to the surface, it can be harmful to your lungs and to plants.

But L.A.’s citizens can breathe a little easier: The study found that the city’s ozone levels are also decreasing.

“To most people,” says Pollack, “the big deal is that things have gotten a lot better.”

Privacy Policy




Here's something interesting from