While our highly industrialised, technological society has many benefits in terms of advanced medical care, economic growth and improved living standards, the Earth is paying a price that is already impacting upon our lives and will do so even more in the future. The 200 years of the Industrial Revolution have introduced waste products of an unprecedented nature and scale that threaten the stability of the whole Earth’s environment.

It was probably the photographs taken of the Earth from space that first made us realize that ours is really quite a small planet, limited in its capacity to absorb pollution. The composition of the whole atmosphere is endangered by destruction of the ozone layer, global warming and acid rain.

Ozone depletion

Ozone is a molecule of three oxygen atoms, formed by ultraviolet radiation splitting oxygen molecules in the upper atmosphere. The ‘ozone layer’ refers to a concentration of ozone in the stratosphere about 15-50 km/9-31 miles above
the surface of the Earth. This is a beneficial shield protecting life from the damaging effect of ultraviolet radiation emitted by the sun. In contrast, the ozone formed lower down in the atmosphere by sunlight reacting with pollution such as that from car exhausts, industry and the burning of fossil fuels is harmful to animal and plant life.

It is believed that the ozone layer formed some 400 million years ago as plants emitted oxygen, a byproduct of photosynthesis, the conversion of carbon dioxide and water into organic chemicals. By reducing the intensity of ultraviolet radiation, the ozone layer allowed life to venture out safely on to dry land from the protective waters.

The ozone layer has always been affected by environmental influences such as volcanic eruptions and solar flares. Now there is evidence that it is being reduced by human activity, mainly by the use of chemicals called CFCs (chlorofluorocarbons) in refrigeration, solvents and aerosols.

What happens?

Increased ultraviolet light multiplies the risk of skin cancer, cataracts and possibly genetic damage. It may damage micro-organisms, affecting fish populations and food production. However, much of this is still theory.

What can be done?

In 1992 more than 70 countries signed the Montreal Protocol, an agreement that Cl’CS would be phased out. However, because they remain in the atmosphere for decades, it will be many years before regeneration of the ozone layer is possible; a reduction in the speed of its decline is the most that can be achieved in the short term.

Global warming

The temperature of the world has always fluctuated and has been a major factor driving evolution. The Earth’s temperature depends largely on the insulating properties of the atmosphere and the balance between heat gained from the sun and heat lost by radiation from the earth. This balance is threatened by gases given off by industry, especially carbon dioxide, largely from burning coal and wood and from car exhausts; methane, from agriculture and rubbish tips; nitrous oxide, from burning coal and oil, and from nitrogen fertilizers; and era.

What will happen?

These gases trap more heat in the atmosphere leading, in theory, to global warming. The concentrations of these gases have risen as a consequence of the 100-fold increases in global energy use in the last 200 years. As the world emerged from the last ice age, global temperatures rose by about 5°C/9°F over several thousand years. Now, computer models used by the Intergovernmental Panel on Climate Change predict a rise in temperature of 1.5-4.50C/2.7-8.10F by the end of the 21st century – an astoundingly rapid and worrying rise. This rate of change is 2-5 times faster than that to which natural ecosystems are able to adapt.

It is believed that the result of global warming will be much more unstable weather, with more droughts, cyclones and Hoods, bringing increased susceptibility to disease and to heat-related deaths. Tropical diseases such as malaria may spread to previously temperate zones. Some low-lying islands may be lost altogether as polar icecaps melt and the sea levels rise.

What can be done?

The way ahead is not at all clear. Experts do not agree whether global warming is a true phenomenon or just a temporary blip in climate. There is not any worldwide agreement on the threat, let alone coordinated action to counter it. Many developing countries continue to rely on coal and wood burning, while in the developed world people remain wedded to their cars. Scientists fear that these pollutant gases will actually increase as a consequence of escalating industrialization.

Acid rain

This phrase is not a new invention of the modem Green movement but was first used in the 1850s in Manchester. Acid rain is mostly from sulphur dioxide dissolved in water, forming sulphuric or sulphurous acid. Some is from nitrogen oxides, from vehicle exhausts. These gases are given off in vast quantities by industrial processes that bum wood or coal: the worldwide output into the atmosphere has increased from 7 million tons per annum in 1860 to over 150 million tons by the late 1980s.
What does it do? By increasing the acidity of rivers and lakes, acid rain kills fish, damages forests and so indirectly affects human well-being. However, studies so far show that drinking slightly acidified water appears not to have any direct eflect on human health.

What can be done?

Stringent environmental industrial controls in the developed world are reducing the output of sulphur dioxide gases, albeit slowly. However, these are still major pollutants in the developing world, especially in newly industrial countries such as China and India.

Pollution – Localised issues

Our economy depends on thousands of industrial processes using thousands of chemicals, many of which are toxic if they escape into the air, food and water.
India, which killed 2500 people in 1984. However, general atmospheric pollution is responsible for a great increase in asthma, chest conditions and eye irritation, particularly among children. Carbon monoxide is emitted by vehicles, cookers and heating devices; an excess causes headaches, drowsiness and even coma and death.

Lead pollution was much greater in previous centuries than now; output has more than halved in the last 25 years thanks to control of lead in petrol, paints, toys and plumbing. The effect of lead in the air is controversial but it does appear to reduce 10 in children. If eaten, lead can cause anaemia, abdominal pains and nausea.

Dust is another serious pollutant. Its effects are linked with asthma and chronic chest diseases such as bronchitis. There is increasing concern about dust produced by diesel fumes.

Water

The negligent disposal of waste – chemical residues, pesticides and metals such as lead, copper and mercury -almost inevitably ends in pollution of rivers, lakes or seas, thereby reducing fish stocks and aquatic life in general. Specific examples of toxic effects on humans are harder to come by. The worst documented example was in Japan in the 1950s, where the discharge of mercury wastes into Minamata Bay was linked to hundreds of deaths and deformities.

Otherwise, evidence is more circumstantial, for example inhabitants of polluted areas of the former USSR have worse infant mortality, lower life expectancy and greater incidence of cancers, although socio-economic factors do complicate the picture.

Food

From contamination of water it is a short step to the contamination of food, again with heavy metals such as lead, mercury and other organic compounds. It is hard to show examples of definite general harm except where a single food is involved. However, much current concern revolves around organophosphate pesticides, which may contaminate via air or skin, causing nausea, muscle weakness, breathing difficulty and depression.

Air

Our air is contaminated by gases, dusts and tiny particles called particulates. It appears not so much that one single component causes damage, but rather a cocktail of pollutants if they arc further degraded by ultraviolet light. This can cause photochemical smog, as in Los Angeles.

The effect on health of the output of a single factory or power station is hard to measure except in the case of unusual accidents, for example the release of toxic fumes at Bhopal in

The future

Many lessons have been learnt about the safe disposal of chemicals and control of industrial gases and dust, although the controls set in place are not totally effective. The biggest questions remain unanswered regarding the future of the ozone layer and global warning, the effects of which may transform climatic conditions in ways that still cannot be accurately predicted.