Image: AIRS/JPL, NASA
The Beijing Municipal Environment Protection Bureau can diminish man-made pollution by shutting down factories and keeping drivers out of cars, but it cannot fight geology. As Donald Morrison of the New York Times puts it, “Beijing is built on dust.”
It is loess, silt and clay from of the erosion of cultivated land to the north and west, quartz, feldspar, calcite, chlorite and mica. It is a problem in the wind-eroded farmlands, and a problem in the city. Spring duststorms are a feature of Beijing life in the spring, from March to June, but despite the claims of local chamber-of-commerce types, the spring rains do not entirely rinse the city’s dust away. Summer winds from the east will bring fresh dust, and any breeze will raise dust deposits from springs past.
Beijing dust is well-known to millions of Chinese people and travelers, and apparently everyone but the International Olympic Committee. Perhaps the IOC visited during the winter.
Beijing dust is so famous that it has a dish named after it. Why should athletes apologize for wearing face masks?
NotionsCapital 
August 16, 2008 at 7:39 pm
[…] when AQI is generally better. Much of the fine particulates in the Beijing air consist of mineral dust prevailing winds carry from the Gobi desert and western plains, not products of factory […]
January 4, 2012 at 12:42 am
UPDATE:
“Weather deserves medal for clean air during 2008 Olympics,” Mary Beckman, Pacific Northwest National Laboratory