Smoke School History

In 1944, the Los Angeles city council discussed moving LAX to a higher elevation area to alleviate flight interruptions caused by increasing smog problems.

Los Angeles already had a history of air pollution. In 1903, smog was so thick that residents thought it was an eclipse of the sun. In 1943, the city suffered a "gas attack" where smoke and fumes covered downtown and cut visibility to three blocks — an almost unbearable phenomenon that produced stinging eyes and severe sore throats.

The City of Los Angeles developed the equivalent opacity concept, extending smoke density measurements to white smoke and associating it to the Ringelmann scale in terms of how much obscuring power the black or white plume had.

In 1945, the council began debating how to address air pollution. In 1946, the Los Angeles Times hired an air pollution expert who developed 23 recommendations to reduce the pollution.

By 1947, the city established the first governmental agency to address air quality — the Los Angeles County Air Pollution Control Board, which later became the LA County Air Pollution Control District.

On October 27, 1948, a yellow fog enveloped the city of Donora and the nearby village of Webster. The Donora smog was caused by an air inversion, lasted four days, and was the worst air pollution event in U.S. history. The smog resulted in 20 deaths and 7,000 illnesses. The Donora smog is considered the catalyst for clean air programs in the United States. Following the disaster, a congressional investigation was instituted and President Truman convened the first national air pollution conference in 1950.

The Great Smog of London occurred December 5–9, 1952. A 30-mile-wide air mass created by a temperature inversion trapped cold air at ground level, producing a noxious smog that smelled like rotten eggs and reduced visibility to a degree where people could not see their feet as they walked. Death estimates range from 8,000 to 12,000. The Great Smog led to the passing of the UK's Clean Air Act in 1956.

After the Donora disaster, pollution gained an audience at the federal level. In 1949, President Truman established a federal committee on air pollution coordinated by the Secretary of the Interior. The first conference on air pollution was held in May 1950 in Washington, D.C.

The first significant legislation was the Air Pollution Control Act of 1955, which provided federal funds for government research on air pollution. Many environmental historians consider this legislation the precursor to the Clean Air Act (CAA) and Clean Air Act amendments (CAAa).

In 1950, California Rule 50A was passed, designed to limit pollution by requiring use of the Ringelmann system in reading smoke. Rule 50A was important because it provided a basis used by all U.S. states and was referenced in 1970 to develop the New Source Performance Standards (NSPS).

In 1953, Los Angeles County began conducting smoke schools. Their program was used as a model for standardization of visible emissions observation (VEO) programs throughout the U.S.