Geoloblog

Environmental science, traveling, and the sociology of the unraveling American dream.

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If you're looking for more about me, I'm pretty much hanging out over at my livejournal these days. I use this account for commenting on other people's blogs.

Saturday, January 15, 2005

Smoke and fog

The Great Smog of 1952 sounds rather like a poorly conceived disaster movie -- but even if no Hollywood funding would go into such a title, the event did happen. The historic pea souper fogs of London one reads about in Dickens and Doyle were actually what we today think of as smog -- a mixture of smoke and fog. In one particular incident in London, in December of 1952, an estimated 4,000 people died as the result of a particularly nasty smog attack, the result of a stagnant weather system and increased coal consumption during a cold snap.

That night and on the Sunday and Monday nights, the fog again thickened. In many parts of London, it was impossible at night for pedestrians to find their way, even in familiar districts. In the Isle of Dogs, the visibility was at times nil. The fog there was so thick that people could not see their own feet! Even in the drier thoroughfares of central London, the fog was exceptionally thick.

From Historical Weather Events.

The air, we're told, is cleaner nowadays, which is true, the result of new and improved baghouses on coal-fired power plants to filter out particulate, increased restrictions on emissions from vehicles, and other such measures. But most of the improvements have come in the larger particulate in the air -- the stuff larger than 2.5 microns -- whereas the majority of the health effects are thought by many to come from the stuff smaller than 2.5 (more commonly referred to as PM 2.5). PM 2.5 is smaller -- harder for both the mechanical filters used to control particulate air emissions and the mucus membranes that serve as your natural defense filters.

Maps of current PM 2.5 and ozone concentrations in your area are available from the EPA.