U.S. readings show ` ` hazardous '' air while Canada reports ` ` slight . '' China 's readings do not include fine air . China 's state - run media expresses distrust over official smog data . China 's weather has compounded the problem in recent days .
U.S. readings show `` hazardous '' air while China reports `` slight pollution '' China 's readings do not include fine particles . China 's state-run media acknowledges distrust over official smog data . Beijing 's weather has compounded the problem in recent days .