Nitrogen Oxides Emission - An Important Environmental Protection Issue for China   

"If there is no control for nitrogen oxides (NOx) emission, China's effort to cut sulfur dioxide emissions by 10% during the Eleventh Five-year Program (2006-2010) will be entirely offset by the nation's rapidly increasing nitrogen oxides emission." This viewpoint was agreed upon by most experts who attended the Technology Seminar for the Control of Nitrogen Oxides Air Pollution held by the Science and Technology Standards department of the Ministry of Environmental Protection. A recent study shows that if China does not take effective measures to control the emission of nitrogen oxides, the emission will continue to go up in the next 15 years, possibly reaching 30 million tons in 2020. Such huge emissions will certainly have a serious influence on public health, the environment and the social economy.
   
Nitrogen oxides should be taken as the important pollutant to be controlled during the Twelfth Five-year Program (2011-2016)

In the seminar, the attending experts all agreed that China should strengthen the control on nitrogen oxides while not loosening control of sulfur dioxide. Through remote detection by satellite, it was found that the increment of nitrogen dioxide concentration in the eastern region of China is markedly higher than in any other region in the world. The air troposphere that covers the densely aggregated industrial area between Beijing and Shanghai has become the part of the world's troposphere most seriously polluted by nitrogen dioxide.
    Another study reported that the significant increment of nitrogen oxides emission turned the pollution mode of acid rain in China from the sulfuric acid-led one to one combining by sulfuric acid and nitric acid. The proportion of nitrate ions in acid rain gradually ascended from 1/10 in the 1980s to 1/3 in recent years, which shows that the emission of nitrogen oxides has become another serious pollutant in acid rain.

In addition to nitrogen dioxide, the emission of other nitrogen oxides such as NO, N2O, N2O4 and N2O5 also need to be controlled  

In 2000, the former State Environmental Protection Administration issued the Environmental Air Quality Standard, but not including the standard of nitrogen oxides and loosening the secondary standard of nitrogen dioxide. Now many of attending experts thought that this standard considered the first influence of nitrogen oxides pollution to the health of people only, but neglected the other multiple influences of nitrogen oxides to fine particles, ozone creation, etc. The highly rectified rate of nitrogen oxides in the air for most cities conceals to some extent the real pollution status of nitrogen oxides in China.

The main regions and industries that emit nitrogen oxides

According to estimates, between 1995 and 2005, the annual growth rate of nitrogen oxides emission in China was more than 6%. In 2005, China's overall emission of nitrogen oxides reached 19.90 million tons. The biggest share was contributed by the companies generating electricity by combustion (mostly coal), accounting for 36%, followed by the manufacturing and transportation industries, accounting for 23% and 20% respectively. Research and investigation shows that most enterprises are not aware of the serious influence of nitrogen oxides emission except the electric power generating enterprises, and the environmental protection departments do not give enough emphasis to supervising the emission of nitrogen oxides; neither enterprises nor the environmental protection departments are aware of the harmfulness of nitrogen oxides.
   Broken down by spatial distribution, nitrogen oxides are mainly emitted in China's eastern region. According to calculations, 80% of the nitrogen oxides emission comes from the middle and eastern regions which have dense population, concentrated industries and rapidly developing economies - including Guangdong, Liaoning, Hebei and Shandong provinces and Shanghai, Beijing and Tianjin municipalities. In emission intensity by unit of land area, Shanghai, Tianjin and Beijing ranked at the top.

China's environmental protection industrial level needs to be improved urgently, some key technologies and materials depend on importation

In the seminar, the attended experts put forwarded another issue that in order to control the sulfur dioxide pollution, many foreign technologies are imported, leading to a fact that the real earners are those foreign companies in the promotion of wiping off sulfur dioxide. To control the emission of nitrogen oxides, it means the flue gas needs to draw out nitrogen oxides before discharging. A lot of problems exist in the process of drawing out nitrogen oxides from flue gas for China. At present, the domestic environmental protection technology level needs to be improved urgently, some key technologies and materials depend mainly on importation.