World Pollutionwatch

An apartment building rises above the smog
An apartment building rises above the fog in Hefei, Anhui province, China. Photograph: Jianan Yu/REUTERS

The twitter feed from the pollution monitor on the roof of the US embassy keeps Beijing's air pollution in the international spotlight. Less attention is paid to the measurements from the Beijing Environment Bureau. This reveals some impressive reductions in traffic pollution in the last decade and attributes a lot of the city's particle pollution to industrial coal and perhaps wood burning in the surrounding regions. With particle pollution able to stay in the air for a week or more it comes as no surprise that China's air pollution problems go beyond Beijing; nine other cities in China had worse air pollution than Beijing during 2013. The US embassy service has extended their pollution information in China; you can now follow tweets from the roof of their embassy in Shanghai.

Although the current focus of the world's media is on Beijing, other cities have been in the air pollution limelight recently, including Paris and London. These are places where we have good measurements, but huge knowledge gaps exist outside Europe and North America. Satellites can measure total air pollution below them but they struggle to resolve the air that we breathe in the bottom one or two kilometres of the atmosphere and in our towns and cities.

Despite this, initial attempts to measure air pollution from satellites have revealed more areas of the world with dense populations and high air pollution. In addition to east China, these include sub-Saharan Africa and central South America, where biomass burning is commonly used for heating and cooking, and northern parts of India and Bangladesh, especially during winter.