Chinese standards, in tandem with the topography (mountains surrounding the city on three sides), leads to particularly oppressive summer weather and the city being named as a candidate for the fourth "furnace", c.e. Three Furnaces. Extremes since 1951 have ranged from on 17 January 1953 to on 24 July 1955. Air quality According to the National Environmental Analysis released by Tsinghua University and The Asian Development Bank in January 2013, Jinan is one of ten most air polluted cities in the world. Also according to this report, 7 of 10 most air polluted cities are in China, including Taiyuan, Beijing, Urumqi, Lanzhou, Chongqing, Jinan and Shijiazhuang. As air pollution in China is at an all-time high, several northern cities are among the most polluted cities and have some of the worst air quality in China. Reporting on China's air quality has been accompanied by what seems like a monochromatic slideshow of the country's several cities smothered in thick smog. According to a survey made by "Global voices China" in February 2013, Jinan is among China's 10 most polluted cities, and is the only Shandong city to be on this list. Other cities on the blacklist includes major Chinese cities like Beijing, Shijiazhuang, Zhengzhou, and 6 other prefectural cities all in Hebei Province. These cities are all situated in traditional geographic subdivision of "Huabei (North China) Region". A dense wave of smog began in the Central and Eastern part of China on 2 December 2013 across a distance of around , including Jinan and surrounding Shandong area. A lack of cold air flow, combined with slow-moving air masses carrying industrial emissions, collected airborne pollutants to form a thick layer of smog over the region. Officials blamed the dense pollution on lack of wind, automobile exhaust emissions under low air pressure, and coal-powered district heating system in North China region. Prevailing winds blew low-hanging air masses of factory emissions (mostly SO2) towards China's east coast. Administrative divisions The sub-provincial city of Jinan has direct jurisdiction over ten districts and 2 counties after the annexation of Laiwu to Jinan in 2019: These are further divided into 146 township-level divisions, including 65 towns, 27 townships and 54 subdistricts. Economy With the shift of the Yellow River to a new bed right to the north of Jinan (in 1852) and the establishment of a railroad hub, the city became a major market for agricultural products