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A man wearing a face mask crosses a street backdropped by the National Palace shrouded by haze, in the Zocalo, Mexico City’s main square, Thursday, May 16, 2019. A siege of air pollution blanketing the capital has led to school closures and the cancellation of professional sporting events. (AP Photo/Rebecca Blackwell)
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Cuban tourist Fernando Castillo wears a face mask as he sits on a bench on pedestrian Madero Street in the historic center of Mexico City, Thursday, May 16, 2019. Castillo and the three Cuban friends he is traveling with have all opted to use face masks while visiting the Mexican capital during a siege of air pollution that has led to the closure of schools and the cancellation of major sporting events. (AP Photo/Rebecca Blackwell)
MEXICO CITY – Mexico City officials have cancelled classes for millions of students as smoke from brush fires continues to choke the city of 9 million.
A light rain overnight has done little to cut the pollution, which remained at about 1 ½ times acceptable limits.
The city declared a partial driving ban, but activists of the Citizen Observatory on Air Quality called Thursday for officials to limit polluting activities like trucks and construction sites.
The activists said the city should include extremely small particles as a cause for imposing emergency measures. Such particles are frequently found in smoke, diesel exhaust and dust. Emergency measures are currently imposed mainly for ozone levels.
The group said "forest fires are unfortunately going to be an ever more frequent problem as a result of global warming."