Outdoor air pollution is one of China's most serious environmental problems. Coal is still the major source of energy, constituting about 75% of all energy sources. Consequently, air pollution in China predominantly consists of coal smoke, with suspended particulate matter (PM) and sulfur dioxide (SO_2) as the principal air pollutants. In large cities, however, with the rapid increase in the number of motor vehicles, air pollution has gradually changed from the conventional coal combustion type to the mixed coal combustion/motor vehicle emission type. Currently, inhalable particles (PM <10 mum in aerodynamic diameter; PM_10), SO_2, and nitrogen dioxide (NO2) are the criteria pollutants of concern in China. Generally, PM levels in cities in the north are higher than those in the south, whereas SO_2 and NO_2 levels do not differ much. In 2004, the annual average PM_10 concentrations for major Chinese cities were 102 ug/m~3 in southern cities, 140 ug/m~3 in northern cities, and 121 ug/m~3 in cities nationwide. The annual average concentrations of SO_2 and NO_2 nationwide were 66 mumg/m~3 and 38 mumg/m~3, respectively (China State Environmental Protection Agency 2005).
展开▼
机译：室外空气污染是中国最严重的环境问题之一。煤炭仍然是主要的能源，约占所有能源的75％。因此，中国的空气污染主要包括煤烟，其中悬浮颗粒物（PM）和二氧化硫（SO_2）是主要的空气污染物。但是，在大城市中，随着机动车数量的迅速增加，空气污染已从传统的燃煤类型逐渐变为混合燃煤/机动车排放类型。目前，可吸入颗粒物（空气动力直径PM <10微米; PM_10），SO_2和二氧化氮（NO2）是中国关注的标准污染物。通常，北部城市的PM水平高于南部城市，而SO_2和NO_2的水平相差不大。 2004年，中国主要城市的年平均PM_10浓度在南部城市为102 ug / m〜3，在北部城市为140 ug / m〜3，在全国城市为121 ug / m〜3。全国SO_2和NO_2的年平均浓度分别为66μmg/ m〜3和38μmg/ m〜3（中国环境保护总局，2005）。
展开▼
