The smoke is an unwelcome visitor from south of the Rio Grande and from across the Gulf of Mexico. Fires have destroyed more than a million acres of vegetation in drought-stricken Mexico and Central America this year. Some have been caused naturally, but many are being blamed on farmers clearing the land, and on drug traffickers intent on diverting state resources away from drug-detection and into firefighting operations.
We in Britain are spared from such horrors, but that has not always been the case. Right up to the 1960s coal-fired power stations and factories, as well as millions of domestic coal fires in the middle of our cities helped to produce smoky fogs that are almost unimaginable today.
In London, between 5 December and 8 December 1952, the visibility was so bad that movement on foot was impossible, and in the Isle of Dogs, according to The Weather of Britain, the bible of weather lore by Robin Stirling, it was reported that people lost sight of their own feet, and blowing your nose left a black mark on the handkerchief for some days.
Such pea-soupers are now rare. The last coal-fired power station in London, Battersea, closed 18 years ago and it is illegal in many conurbations to burn raw coal in domestic fires. Sadly, the increase in traffic is helping to push air quality down again.