Persistent heavy smog on Tuesday caused massive flight delays in and around Beijing, snarling traffic and even pushing up vegetable prices in the capital, according to The South China Morning Post. By 6pm, 359 flights at Beijing Capital International Airport had been cancelled, according to an airport statement. At least 23 cities in the north had issued red alerts for air pollution, and smog covered a seventh of the country, China News Service reported. In smog-bound Tianjin, 243 flights were cancelled and 63 delayed by 5pm. Massive delays were also reported in Jinan and Qingdao in Shandong province. In Beijing, visibility fell to below 200 metres and some highways on the sixth ring road and main roads connecting the capital to neighbouring cities in Hebei and Tianjin were closed.