May 1, 2009
Asian emissions soar
China is currently experiencing one of the fastest industrial revolutions the world has ever seen - two new power stations open every week to meet rising energy demand. Accompanying this phenomenal growth is a huge rise in pollution. Now new measurements reveal just how rapidly China's skies are darkening, with some pollutants increasing by more than 50% over a five year period. The findings also raise concerns about the pollution billowing over the Pacific Ocean, contributing to smogs in cities on the West coast of the US.
Qiang Zhang, from the Argonne National Laboratory in Illinois, US, and his colleagues, estimated anthropogenic atmospheric emissions from Asia during 2006. They collected official statistics that represent measures of activity (for example tons of coal burned, tons of gasoline consumed, tons of steel produced and megawatts of electricity generated). By combining this with estimates of emission rates for various pieces of industrial equipment they were able to calculate the tons of pollutant emitted for each kind of activity.
In total the survey covered twenty-two countries, stretching from Pakistan in the West to Japan in the East and from Indonesia in the South to Mongolia in the North. However, the major focus of the research was on China, because of the rapid development occurring there.
Over the five year period between 2001 and 2006 the researchers found that all Chinese emissions had increased. They measured a 36% increase in sulphur dioxide emissions, 55% for nitrogen oxides, 18% for carbon monoxide, 29% for volatile organic compounds, 13% for PM10 (particulate matter smaller than 10 micrometres in diameter), and 14% for PM2.5 (particulate matter smaller than 2.5 micrometres in diameter), black carbon, and organic carbon. The results are published in the journal Atmospheric Chemistry and Physics Discussions.
"We believe that emissions of nitrogen oxides have increased the most due to a combination of rapid expansion of electricity generation (new power plants built) and increasingly more cars and trucks," David Streets, another member of the research team from the Argonne National Laboratory, told environmentalresearchweb. "Sulphur dioxide has not increased as fast because of the introduction of emission controls for sulphur dioxide on power plants."
Both sulphur dioxide and nitrogen oxides are involved in acid rain formation and cause human health problems, such as ozone formation, in urban environments. Volatile organic compounds, carbon monoxide and particulate matter are all bad for human health, while carbon monoxide is also a measure of poor combustion. Black carbon and organic carbon are aerosols and contribute to climate change.
Chinese cities are now renowned for their poor air quality, and it is clear that the ozone and toxic smogs are having a detrimental effect on human health. However, it is not just Chinese cities that are being choked by the fumes.
Some pollutants remain in the atmosphere for up to a month, often becoming entrained in weather systems and transported across the Pacific Ocean. Many arrive on the west coast of North America, and sometimes the Arctic. "It has been shown that Asian particles contribute to pollution levels on the west coast of North America. In extreme cases, the imported contribution can be sufficient to cause violation of local air quality standards," said Streets.
Zhang and his colleagues are using the new data to support a NASA-funded project known as Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), to better understand the outflow of pollution from the Asian continent and subsequent transport across the Pacific Ocean.
The new information will help policy makers decide how best to tackle the problem, and hopefully it will also encourage other countries to help out. "There are benefits both to China and to its neighbours to reducing emissions. The wealthier countries can contribute technology and experience to get the job done to the benefit of all," said Streets.
About the author
Kate Ravilious is a contributing editor to environmentalresearchweb.