Beijing, Dec 25, IRNA - Dense air pollution has cancelled IranAir's Beijing-Tehran flight in the Chinese capital on Friday. Talking to IRNA, an IranAir Director in Beijing Behrouz Saadati said the Bejing-Tehran flight is awaiting the permit from Chinese capital's airport. Saadati reiterated that Beijing airport has cancelled over 500 flights after dense smog reduced visibility in the Chinese capital on Thursday night. He also expressed hope that IranAir flight could receive the flight permit soon. According to reports by UN, Beijing is considered to be one of the most polluted cities in the world. The high level of air pollution comes from burning fossil fuels, particularly coal, and from vehicle emissions. By IRNA