science · 14 October 1947 · 77 years ago
In 1947, the Los Angeles County Board of Supervisors established the first U.S. air pollution control program by creating the L.A. County Air Pollution Control District. It responsed to the serious smog in the city on 26 Jul 1943 when a noxious haze of smoke and exhaust fumes reduced visibility to under three blocks. From Oct 1943, a Smoke and Fumes Commission studied the problem. It named many cause: locomotive smoke, diesel truck fumes, back-yard rubbish burning plus the mountain topography, stagnant winds and atmospheric temperature inversions. On 31 Jul 1954, a six-year research program reported that the smog was caused by the chemical reaction of sunlight on auto and industrial emissions. London's killer Great Smog on 5 Dec 1952, led to the Clean Air Act of 1956.
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