Air Pollution                                                      Cymraeg

The other pollutants from petrol, diesel and alternative fuel engines are mainly Carbon Monoxide, Oxides of Nitrogen, un-burnt Hydrocarbons and fine particles. The first three are gases and are invisible. Fine particles are usually invisible although in certain operating conditions diesels will produce visible particles, appearing as smoke. Petrol engines will also produce visible particles if they are burning engine oil or running rich, for example, following a cold start. Unlike CO₂, emissions of these pollutants are not directly linked to fuel consumption. Pollutant levels are more dependant on vehicle technology and the state of maintenance of the vehicle. Other factors, such as driving style, driving conditions and ambient temperature also affect emission of pollutants. However, as a starting point new passenger cars must meet minimum EU emissions standards.

The main exhaust gas pollutants and their effects are described in more detail below:

CO - Carbon Monoxide reduces the blood’s Oxygen carrying capacity which can reduce availability of Oxygen to key organs. Extreme levels of exposure, such as might occur due to blocked flues in domestic boilers, can be fatal. At lower concentrations CO may pose a health risk, particularly to those suffering from heart disease.

NOx - Oxides of Nitrogen react in the atmosphere to form Nitrogen Dioxide (NO2) which can have adverse effects on health, particularly among people with respiratory illness. High levels of exposure have been linked with increased hospital admissions due to respiratory problems, while long term exposure may affect lung function and increase the response to allergens in sensitive people. NOx also contributes to smog formation, acid rain, can damage vegetation and contributes to ground level Ozone formation.

Particles - Fine particles can have an adverse effect on human health, particularly among those with existing respiratory disorders. Particles have been associated with increased hospital admissions due to respiratory problems and bringing forward the deaths of those suffering from respiratory illnesses.

HC - Hydrocarbons, contribute to ground level Ozone formation leading to risk of damage to the human respiratory system. In addition, some kinds of HCs are carcinogenic and they are also indirect greenhouse gases.

Of the above, Nitrogen Dioxide and fine particles are considered to be two of the most significant air pollutants, especially in urban areas. The Government is convinced that action to reduce harmful emissions must continue. Its approach to tackling air pollution is set out in the Air Quality Strategy for England, Scotland, Wales and Northern Ireland. This sets health based standards for eight main air pollutants, from which air quality objectives are derived, together with a timescale for their achievement. The Strategy identifies the action required at a national and international level, and the contribution industry, transport and local government can make to ensure objectives are met.

Emissions of the above pollutants are being reduced by improving the quality of fuels and by setting increasingly stringent emission limits for new vehicles. As an example it would take 50 new cars to produce the same emissions per kilometre as a vehicle made in 1970. For the last twenty years emission limits have been set at a European level and are quoted in grams of pollutant per kilometre travelled.

In 1992 exhaust emission limits, (generally referred to as the Euro I standards) were introduced for new cars which resulted in the fitting of advanced emission control techniques, e.g. catalysts. More stringent emission limits came into effect in 1997 and 1998, depending on vehicle type, and are known as Euro II.

Stricter emission requirements, generally referred to as Euro III, were introduced with effect from 1st January 2000 and, for the majority of vehicles, came into full effect on 1st January 2001. Vehicles which meet this standard are listed in Part B of the booklet. A further tightening of the emissions limits, referred to as Euro IV, began on the 1st January 2005 and will be fully in force by 1st January 2007. Some manufacturers have chosen to approve cars to Euro IV limits ahead of time and these are listed in Part A of the booklet.

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