The dust from the plains in the “dust bowl” in the 30s reached all the way to NYC with reduced sunlight
The dust from China’s western deserts combines with chemical pollution (mostly coal burning power plants) fouling Beijing’s air constantly. If Beijing was in the west of China and it’s deserts in the east, Beijing’s air would be only partially as bad as it often is. Again - the earth’s rotation determines a lot about airflows in the atmosphere. Its not mysterious.