|
| Block 8: Environmental Issues and Public Health - Air Pollution Chapter 9: Cleaner Production; Pollution Control And Economic Development |
 |
 |
 |
 |
The control of emissions from vehicles requires both cleaner fuels (a reduction on the sulphur content of petrol and diesel, the use of lead-free petrol) and the use of emission control devices such as catalytic converters on cars. A reduction in the sulphur content of diesel results in lower PM and SO2 emissions. The use of unleaded petrol not only eliminates lead emissions but enables the use of catalytic converters in car exhaust systems. Catalytic converters are capable of reducing CO, NOx and VOC emissions by about 90%.
The South African government has adopted a policy to introduce cleaner fuels - to stop the sale of leaded petrol, and to reduce the maximum sulphur content of diesel from the current level of 3000 ppm to 500 ppm - by January 2006, and to phase in the compulsory installation of catalytic converters in new cars. The average life of a car is over ten years. The vehicle population therefore changes relatively slowly, and the benefits of the new technology will therefore only gradually become apparent.
In the long term, the benefits of a reduction in vehicle emissions due to the introduction of emission control technology is likely to be reversed by the increase in the total number of vehicles. A long term solution to the problem of vehicle emissions must include a viable public transport system and other measures to reduce or limit both the number of private vehicles and the activity rate (number of kilometers travelled per year).
"Economic Development" may be interpreted to imply an increase in economic activity, with an attendant increase in the demand for energy, industrial activity and transport and the pollutant emissions associated with these activities. However the development and use of cleaner technologies and different approaches to satisfy energy and transport needs means that increasing economic activity and environmental impacts can be uncoupled. That is, an increase in ecoinomic activity does not have to lead to increase environmental impacts.
Modelling tools may be used to evaluate future scenarios, for example the impact of increased activity such as road traffic or the increased emissions arising out of new stationary sources. With the use of stricter emission controls (Best Available Technology or Techniques), improved emission standards or Cleaner Production methods it is possible to progressively reduce impacts whilst allowing increased activity. Modelling can be used to evaluate the potential improvements of different options, and to do a cost-benefit analysis.
Three major areas of activity that have long-term implications for the relationship between development and environmental impacts (including human health impacts) are: solid waste generation and disposal systems, energy consumption and methods of energy generation and public transport.
As an example of the use of modelling tools to evaluate different scenarios, the following graph illustrates the beneficial impact of the introduction of 3-way catalytic controls and cleaner fuels on vehicle emissions in the Cape Metropolitan Area.
 |
| *kT/a = kilotons per annum |