Sahara desert dust shrouds London as 'perfect storm' for air pollution hits

Saharan dust blowing in from North Africa shrouded skyscrapers in London's financial district, coated residents' cars and pushed pollution to high levels yesterday.

The city's pollution index reached seven on a scale of 1-10, meaning those with lung and heart problems should reduce exercise, according to government recommendations.

London faced "high" pollution levels, the state Met Office forecaster said.

Cars outside Prime Minister David Cameron's Downing Street residence were covered with dust blown in from the desert 3,320 kilometres to the south, and the offices of some of the world's biggest banks faded into the haze in east London's Canary Wharf. Dust was thrown up by sandstorms in northwest Africa at the end of March and deposited in rains, the Met Office said in a blog.

"Weather conditions have conspired to create a perfect storm for air pollution," Helen Dacre, a meteorologist at the University of Reading, said.

"British car drivers and heavy industry create bad enough smog on their own, but the weather is also importing pollution."