How bad is pollution in China? So bad you can see it from space.

Wait, can't you do that in the US? Anyone who has flown into Los Angeles in the morning surely sees pollution. 

This is different. And worse. Plumes of several anthropogenic pollutants, especially particulate matter and carbon monoxide, at ground level over China can now be detected from space - something that was only possible higher up previously. The team used measurements by the Infrared Atmospheric Sounding Interferometer on board the MetOp satellite and the findings represent a crucial step towards improved monitoring of regional pollution and forecasting of local pollution episodes, especially in China.

China gets something of a cultural break from the rest of the world about its pollution. While American industry takes the blame for its CO2 emissions, Chinese industry is also blamed on...America. It's easy for environmentalists to blame the US for Chinese pollution but that won't reduce surface emissions or the estimated 300,000 premature deaths blamed on pollution each year. In January of 2013, Beijing suffered an unprecedented pollution episode, mainly due to seasonal coal consumption and unfavorable weather conditions (lack of wind plus temperature inversion) that trapped the pollutants at ground level.

In many regions, atmospheric concentrations of particulate matter (PM) reached values considered harmful to human health, sometimes exceeding the daily threshold recommended by the World Health Organization (25 µg/m3) by a factor of nearly 40. In 2008, for the Olympics, the Communist party had to mitigate pollution by banning cars except for elites.

China has an air quality monitoring network that continuously provides measurements of key pollutants including PM, carbon monoxide (CO) and sulfur dioxide (SO2) but the geographical distribution of measuring stations is patchy, which makes it difficult to predict the development of pollution episodes. Satellite observations have excellent geographical coverage and horizontal resolution but they are best at altitudes of 3 to 10 km. Using satellites to determine atmospheric composition near ground level was complicated until now.

The researchers found that, contrary to expectations, the IASI sounder is able to detect plumes of pollutants even near ground level as long as two conditions are met: weather conditions must be stable, which leads to a build-up of pollutants at ground level, and there must be a significant temperature difference between the ground and the air just above the Earth's surface. In January 2013, IASI measured very high concentrations of anthropogenic pollutants such as CO, SO2, ammonia (NH3) and ammonium sulfate aerosols over Beijing and neighboring cities. The IASI infrared sounder thus proves to be well suited to monitoring these pollutants in such conditions.

With the launch of IASI-B, two IASI sounders are now able to collect infrared data from space and twice as much information has therefore been available since the end of January 2013.

Published in Geophysical Research Letters.