Automobiles and pollution

While the motor car has become an indispensable part of modern life, there is increasing concern about its environmental impact, particularly the negative effects of automotive exhaust emissions on air quality and human health. It has long been acknowledged that pollutants emitted from gasoline-driven vehicles contribute to a decline in air quality. Carbon monoxide, nitrogen oxide and hydrocarbons are all known to be toxic to humans or damaging to the environment.

The proportion of pollutants in the air which are directly attributable to vehicle emissions has risen significantly in line with the growth in car ownership and the increase in the number of kilometres driven per car.

Sources of the principal pollutants:

	CO	NOx	HC
Gasoline vehicles	90 %	52 %	40 %
Domestic	5 %	3 %	2 %
Power stations	1 %	26 %	< 1 %
Industry	4 %	11 %	56 %
Others	-	8 %	1 %

Impact of air pollution on health and environment

Numerous studies have been undertaken in Europe to determine the impact of car emissions on human health and the environment. The results are alarming. In Europe, the 1999 WHO report on Health costs due to road traffic-related air pollution revealed that car-related pollution kills more people than car accidents in the three European countries where the study took place (Austria, France, Switzerland).

The main findings of this report were:

- long-term exposure to air pollution from cars in adults over 30 years of age caused an extra 21,000 premature deaths per year from respiratory or heart disease. This is more than the total annual deaths from road traffic accidents in the countries studied (9,900)

- each year, air pollution from cars causes 300,000 extra cases of bronchitis in children, plus 15,000 hospital admissions for heart disease, 395,000 asthma attacks in adults and 162,000 attacks in children.

The potential harmful effects, both on health and the environment, of the main automobile exhaust pollutants are summarised as follows:

	Health effects	Environmental Effects
Carbon monoxide (CO)	Lethal at high doses. At low doses can impair concentration and neuro-behavioural function. Increases the likelihood of exercise-related heart pain in people with coronary heart disease	Greenhouse gas contributing to global warming
Nitrogen oxides (NOx)	May exacerbate asthma and possibly increase susceptibility to infections	Acid rainGround level ozone precursor
Hydrocarbons (HC)	Low molecular weight compounds cause eye irritation, coughing and drowsiness High molecular weight compounds can be mutagenic or carcinogenic	Ground level ozone precursor
Benzene (C6H6)	Classified as a human carcinogen (Group 1) by the International Agency for Research on Cancer
Ground-level ozone (O3)	Irritates the eyes and air passages. Increases the sensitivity of the airways to allergic triggers in people with asthma. May increase susceptibility to infection	Oxidants to plants, impairs growth and maturation
Lead (Pb)	Impairs the normal intellectual development and learning ability of children	Ground water pollution and particulates in air

Most major cities in Europe now face vehicle-related smog problems. In urban areas, traffic represents an extremely high proportion of emissions. Some of these areas have therefore introduced emergency restrictions on vehicles at weak periods but in our car-dependent society, severe restrictions on private transport are unattractive, yet the serious effects of poor air quality call for action. A significant reduction in air pollution can be achieved by the use of cleaner-burning gasoline and diesel fuels, and this is the decision that the European Union took in 1998 with the adoption of the "Auto/Oil Directive" (Directive 98/70/EC), which came into force in January 2000.