The report on the levels of pollution in Beijing comes from a report issued by the World Health Organization (WHO) and is based on various monitoring stations located throughout China's capital city, USA Today
The latest concern relates to readings taken on Saturday January 12, when the air, a BBC reporter
has stated, is thick with smog and where the "air tastes of coal dust and car fumes".
An assessment of air pollution is made, according to WHO guidelines
, based on the concentration of microscopic particles in a given volume of air. For an area to be satisfactory, WHO recommends that the average concentrations of the tiniest pollution particles (termed PM2.5 for particulate matter of 2.5 microns), should be no more than 25 microgrammes per cubic metre. This size of this particle is about 1/30th the average width of a human hair.
The small size of particle is used as a global measure because it represents the size of particles which can penetrate deep into the lungs. According to WHO
"Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere. Household combustion devices, motor vehicles, industrial facilities and forest fires are common sources of air pollution. Pollutants of major public health concern include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide. Outdoor and indoor air pollution cause respiratory and other diseases, which can be fatal."
The WHO map of global air pollution is illustrated below:
An unhealthy rating is applied when the level of these tiny particles moves above 100 microgrammes. At levels above 300 microgrammes vulnerable groups, like children and the elderly are advised to remain indoors. In Beijing, the official level of pollution, reported via the Beijing Municipal Environmental Monitoring Center, is in excess of 400 microgrammes. However, an assessment by the U.S. embassy, released via a special Twitter account
, puts the level at over 800 microgrammes.
The high levels of pollution in the largest Chinese cities are likely to be a consequence
of China's rapid economic growth including, as the Wall Street Journal
notes, the burning of fuels in vehicles and power plants. As a way of comparison
, an industrialized U.S. city like Detroit recorded an average of 20 microgrammes in 2010 (according to a WHO index
). ABC Net
reports that the most polluted places on the plant include cites in China, India, and Indonesia.