A strong cold front is expected to clear up lingering smog in Beijing on Tuesday night, the city's meteorological bureau said Monday. According to Xinhua, the Chinese capital has been shrouded in heavy smog for five straight days. As the city's air quality has hovered at hazardous levels, the public has been advised to stay indoors and to avoid strenuous exercise. The density of PM2.5 -- airborne particles with a diameter of 2.5 microns or less that can deeply penetrate the lungs -- reached over 900 micrograms per square meter at some monitoring stations on Saturday evening. The municipal meteorological bureau continued to issue the highest alert on smog Monday morning, as the city's downtown and southern areas reported PM2.5 levels of over 250 micrograms per square meter.
