Los Angeles has had air pollution problems since before smog was a term.

In 1943, people began to notice the smog when it covered Los Angeles so thickly that residents thought Japan had launched a chemical attack. The city continued to have smog problems for decades.

President Richard Nixon created the Environmental Protection Agency in 1970, which introduced air pollution regulations, and it was a major factor in combating the city's smog problem.

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The city of stars could be called the city of smog.

Los Angeles has had years of thick air pollution due to a ballooning population, unregulated industry, a booming car industry, and its natural geography.

The Washington Post described it as "eye-burning, lung-stinging, headache-inducing smog."

In 1943, during World War II, pollution blanketed the city so intensely residents thought Japan had launched a chemical attack. Over the next three decades, improvements came, but they were slow.

The biggest victory against smog came in 1970. President Richard Nixon created the Environmental Protection Agency, which led to air pollution regulations, and allowed California to make even stricter provisions within its state.

Here's what it used to be like.