Problems and Concerns caused by Human Influences on the Environment

Domestic Wastes

The millions of people living in large cities produce a lot of waste. Some of this waste is biodegradable. This means it can be broken down by decomposers, such as bacteria. Other types of waste, including some plastics and metals, cannot be decomposed.

Some cities burn waste. The energy released is used to heat homes in the area of the incinerator. Burning waste, however, releases carbon dioxide and other pollutant gases into the atmosphere. This is why incinerators have tall chimneys to make sure that these gases are released at height, away from the population at ground level.

Other cities have waste dumps on their outskirts. The waste is piled up using bulldozers. These dumps attract rats and other vermin, as well as birds. These can carry disease into the cities.

In recent years some European cities have introduced two types of waste bins. The new, green bins are for waste paper which can be recycled.

FACT 1

Since the beginning of the 18th century the human population has increased by 700% and the average life expectancy has doubled. In 1950 the population was 2,5 billion and by the year 2000 the number has passed 6 billion. It has been estimated that the number will be as high as 8,5 billion in the year 2025. Mexico city is the world's largest city; it had a population of 19,4 million in 1990 and this number was expected to reach 24,4 million by 2001.

FACT 2

In 1990 there were three births each second. This means a total of 250000 births each day.

World Population Clock

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© Paul Billiet, Shirley Burchill, Alan Damon and Deborah James 2009