Titolo: St. Paul's Cathedral is seen among the s

Descrizione: St. Paul's Cathedral is seen among the skyline through the smog in central London on April 22, 2011. The British Government have warned of potentially dangerous levels of air pollution with a "smog alert" for the Easter weekend predicted throughout England and Wales. The combination of hot weather and still conditions brought on by the current high pressure system means levels of ozone and polluting particles known as PM10s, which can affect people's health, are expected to increase. AFP PHOTO / LEON NEAL (Photo credit should read LEON NEAL/AFP/Getty Images)

Crediti immagine: AFP/Getty Images - © 2011 AFP