Kim Preshoff |
Smog is a type of air pollutant. The word “smog” was coined in the early 20th century as a portmanteau of the words smoke and fog to refer to smoky fog, its opacity, and odour.
The word was then intended to refer to what was sometimes known as pea soup fog, a familiar and serious problem in London from the 19th century to the mid 20th century.
This kind of visible air pollution is composed of nitrogen oxides, sulphur oxides, ozone, smoke or particulates among others (less visible pollutants include carbon monoxide, CFCs and radioactive sources).
On July 26, 1943, Los Angeles was blanketed by a thick gas that stung people’s eyes and blocked out the Sun. Panicked residents believed their city had been attacked using chemical warfare. But the cloud wasn’t an act of war. It was smog. So what is this thick gray haze actually made of? And why does it affect some cities and not others? Kim Preshoff details the science behind smog.