A cyclist adjusts his protective face mask as he cycles in central London April 2, 2014. Britain's Meteorological Office has forecast that London would be affected by smog this week, caused by ... more 
A cyclist adjusts his protective face mask as he cycles in central London April 2, 2014. Britain's Meteorological Office has forecast that London would be affected by smog this week, caused by powerful dust storms and strong winds in the Sahara. REUTERS/Neil Hall (BRITAIN - Tags: ENVIRONMENT HEALTH SOCIETY) less 
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Reuters | Photo By NEIL HALL / Reuters
Wed, Apr 2, 2014 10:16 AM EDT