Beginning on the evening of February 21, a large-scale temperature inversion blanketed much of North China in a heavy fog, which in urban areas quickly became a choking smog. Visibility in some areas fell as low as 200 meters, leading to multi-vehicle traffic accidents on some expressways, and many canceled flights at regional airports. Although the last few years have seen some improvement, Beijing s winter air quality still suffers from the use of coal for household heating. Dry, windy days are clearer than humid, calmer days.
Pollution is generally most severe in the late fall, when temperature inversions are common.
Springtime duststorms also sometimes contribute to especially low air-quality days. The summer months are ozone season. China needs to unify its five separate regional power grids, according to a People's Daily editorial on February 12. According to the People s Daily , the Three Gorges Dam will begin dispatching power on 500-kilovolt high tension lines to eastern and central China, Chongqing and Sichuan in 2010, and a completely integrated national electric power grid will be set up by 2015. Boost Drug Resistance Widespread reckless use of antibiotics has greatly increased resistance to the most commonly used antibiotics, a Zhejiang Province researcher reported recently.