 
 <prompt> Wetin be di size of di pollution cloud wey dem talk about? Given di previous question, write a context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: ```A thick wave of smog start for Central and Eastern part of China on 2 December 2013 across about 1,200 kilometres (750 mi), including Tianjin, Hebei, Shandong, Jiangsu, Anhui, Shanghai and Zhejiang. Because cold air no dey blow well, combined with slow-moving air wey dey carry industrial emissions, dem gather airborne pollutants to form thick layer of smog for the area. The heavy smog heavy pollute central and southern Jiangsu Province, especially for and around Nanjing, with AQI pollution Index for "severely polluted" for five straight days and "heavily polluted" for nine. On 3 December 2013, levels of PM2.5 particulate matter average over 943 micrograms per cubic metre, come fall to over 338 micrograms per cubic metre on 4 December 2013. Between 3:00 pm, 3 December and 2:00pm, 4 December local time, several expressways from Nanjing to other Jiangsu cities close, come trap plenty passenger buses for Zhongyangmen bus station. From 5 to 6 December, Nanjing issue red alert for air pollution and close down all kindergarten through middle schools. Children's Hospital outpatient services increase by 33 percent; general incidence of bronchitis, pneumonia, upper respiratory tract infections significantly increase. The smog clear 12 December. Officials blame the dense pollution on lack of wind, automobile exhaust emissions under low air pressure, and coal-powered district heating system for North China region. Prevailing winds blow low-hanging air masses of factory emissions (mostly SO2) towards China's east coast.``` 