NEW : Beijing recording `` hazardous '' levels of air pollution Monday . NEW : Children in worst-hit areas ordered to stop outdoor sports activities . Comment: U.S. Embassy in Beijing records an index of more than 700 micrograms Sunday .
NEW : Beijing recording `` hazardous '' levels of air pollution Monday . NEW : Children in worst-hit areas ordered to stop outdoor sports activities . Reports of respiratory problems -- and sale of masks -- skyrocket . U.S. Embassy in Beijing records an index of more than 700 micrograms Sunday .