London was hit by a health alert Wednesday, as a dirty cocktail of dust, car fumes and pollutants swept across the city.
The deluge of the so-called 'Sahara Rain' means people should be braced for "very high" levels of air pollution over the next few days, experts have warned.
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The fine dust, swept from 2,000 miles away, is causing air pollution that can trigger hayfever-like symptoms and cause respiratory problems to flare up.
The dirtiest air was expected to slip to the east of London affecting East Anglia and the East Midlands.
The pollution is expected to start clearing later this week when winds change direction and bring in fresher air from the Atlantic, but for now, here are some pictures of London looking especially grubby: