III. ENVIRONMENT MONITORING AND URBAN PLANNING
C. Survey on automobile exhaust gas emissions and study on control strategies in ShanghaiIt took five years for the number of automobiles in Shanghai to increase from 100,000 in 1985 to 200,000 m 1990, but only another three years to add another l00,000. More recently, an additional 120,000 was added in two years, making the total number in excess of 420,000 by the end of 1995. Emissions of exhaust fumes from the increasing number of automobiles seriously threatens the air environment of Shanghai. With support from the World Bank, studies of automobile exhaust gas pollution in Shanghai were carried out in order to understand the status quo and trends of such pollution, and so to develop appropriate control strategies.
1. Areas of study and survey
2. Research methodologyNearly 30 sites along the Inner Ring Road were chosen to obtain data identifying air pollution by CO, NMHC, NOx and Pb. The survey on the urban road traffic situation and the study of the general running condition of vehicles were carried out simultaneously. In addition, other key aspects concerning the formation of the final control strategies were also undertaken, such as to determine the coefficient of pollutant emission by vehicles, to investigate the management of pollutant emissions and the maintenance of vehicles . On the basis of above knowledge, the study provided an estimate of the emission volume of automobile exhaust gas and its contribution to urban air pollution, and an analysis of the changing trends of such volume and contribution. Finally, control strategies for automobile exhaust gas pollution are put forward.
3. Interesting facts and results of analysis(a) Severe air pollution has been caused by automobile exhaust gas
The average daily concentration of CO near urban main traffic lines
exceeded the national class 2 standard by 27 per cent, with the maximum
concentration surpassing the standard by 2.13 times. The figures for NMHC
were 87 per cent and 3.4 times and for NOx were 85 per cent and 9.0 times.
Figure 35. The research framework for control strategies for urban automobiles exhaust gas pollution in Shanghai
(b) The emission volume of exhaust gas will increase even faster
The emission volume of CO by automobiles m 1995 increased by 23 times compared to the end of the 1980s while NMHC increased by 0.95 times and NOx by 3.2 times. Based on the estimate that the total number of automobiles in 2010 will reach 1.4 million, the emission volume of CO, NMHC and NOx at that time will increase another 3.2, 3.1 and 2.8 times respectively against 1995.
(c) The automobiles exhaust gas has become the main pollutant source in air pollution
In 1995, the contribution of CO, NMHC and NOx emitted from automobiles to the total of all air pollutants reached 76 per cent, 93 per cent and 44 per cent respectively, and these figures are estimated to reach 94 per cent, 98 per cent and 75 per cent by 2010 (table 18). Thus, automobile exhaust gas pollution is going to cause even worse air pollution if not strictly controlled.
Table 18. The emission volume and contribution by urban fixed pollutant sources and automobile exhaust gas
4. Control strategies for automobile exhaust gas pollution in ShanghaiThough the total number of automobiles in Shanghai is much less than that of large cities in developed countries, the contribution of exhaust gas pollution to air pollution is much higher. The main reasons are identified as follows:
Introducing strict exhaust gas emission standards will be helpful in
increasing the future competitive capability and sustainability of the
automobile industry. This is not only demanded by environmental protection,
but also by development of itself.