Major Environmental Pros and Cons of Urban Areas

Because urbanization changes the landscape, it also changes the relationships between biological and physical aspects of the environment.

In terms of resource use, most of the world’s cities are not self-sustaining systems because of their high resource input and high waste output.

Traffic congestion, increased pollution, limited real estate, and decreasing resources are all possible side effects of urbanization.

Urbanization obviously destroys farmland where it occurs and concentrates pollution. Although urban dwellers occupy only about 2% of the Earth’s land area, they consume about 75% of the Earth’s resources. In addition, large areas of the Earth’s land area must be disturbed and degraded to provide urban dwellers with food, water, energy, minerals, and other resources. This decreases and degrades the Earth’s biodiversity.

When an area expands rapidly, it can cause great environmental damage. As cities expand they destroy rural croplands, fertile soil, forests, wetlands, and wildlife habitats.

Peoples' desire for more personal space is leading real-estate developers to buy up land and clear it for housing developments. The destruction of farm land is becoming more and more of an issue.

Habitat is changed and the wildlife with it. With urbanization comes more building, which means loss of habitat. Urbanization through habitat destruction reduces wildlife populations and can lead species to become endangered in certain areas.

Most cities have few trees, shrubs, or other plants that absorb air pollutants, give off oxygen, help cool the air as water transpires from their leaves, provide shade, reduce soil erosion, muffle noise, provide wildlife habitats, and give aesthetic pleasure.

Many urban areas have water resource problems. As cities grow their water demands increase.  Increased demand is met through heavy extraction of groundwater that depletes this resource faster than it is replenished. Many cities have water supply problems. In urban areas of many developing countries, 50—70% of water is lost or wasted because of leaks and poor management of water distribution systems.                                                

City pavement increases the chances of local flooding within the city by overloading the storm drains, and the increased runoff from the city to the countryside can increase the chances of flooding downstream. Paved city streets and city buildings prevent water infiltration. Flooding tends to be greater in cities. One reason is that many cities are built on floodplain areas or along low-lying coastal areas subject to natural flooding. Another reason is that covering land with buildings, asphalt, and concrete causes precipitation to run off quickly and overload storm drains.

Urbanization changes the type of pollution, more so than the amount. There is less nutrient pollution and siltation, more metals and petroleum pollution.

Urbanization increases both surface and ground water pollution as well.

Everything is concentrated in a city, including pollution. Because of their high population densities and high resource consumption, urban dwellers produce most of the world’s air pollution, water pollution, solid and hazardous wastes. Some of this comes from motor vehicles, which have contributed lead in gasoline, nitrogen oxides, ozone, carbon monoxide, and other air pollutants from exhaust. Stationary power sources also produce air pollutants. Home heating is a third source, contributing particulates, sulfur oxides, nitrogen oxides, and other toxic gases. Industries are a fourth source. In addition, high population densities in urban areas can increase spread of infectious diseases and physical injuries. This environment makes life riskier, causing hundreds and thousands of premature deaths each year.

Many urban areas of developing countries have no proper sewer facilities, meaning huge amounts of human waste are deposited in gutters and vacant lots everyday attracting armies of rats and swarms of flies. When the winds pick up dried excrement, a fecal snow often falls on parts of city. This bacteria-laden fallout leads to widespread salmonella and hepatitis infections, especially among children.  In general, life in a city is riskier because of higher concentrations of pollutants and pollutant-related diseases.

                                          

Fig: Massive urbanization in Dhaka resulted in tremendous strain on the city’s infrastructure.

Urban areas suffer from high unemployment, deafening noise, and a soaring rate of crime. Unwanted, disturbing, or harmful sound that impairs or interferes with hearing, causes stress, hampers concentration and work efficiency, or cause accidents. Noise levels above 65 dbA are considered unacceptable, and prolonged exposure to levels above 85 dbA can cause permanent hearing damage. Many of urban population (may be one-third) live in crowded slums or squatter settlements, without running water, or electricity.

An urban heat island is formed when industrial and urban areas are developed resulting in greater production and retention of heat. A large proportion of solar energy that affects rural areas is consumed evaporating water from vegetation and soil. In cities, where there is less vegetation and exposed soil, the majority of the sun’s energy is absorbed by urban structures and asphalt. Hence, during warm daylight hours, less evaporative cooling in cities results in higher surface temperatures than in rural areas. Vehicles and factories release additional city heat, as do industrial and domestic heating and cooling units. As a result, cities are often 2 to 10 °F (1 to 6 °C) warmer than surrounding landscapes. Impacts also include reducing soil moisture and a reduction in re-uptake of carbon dioxide emissions.

Finally, urban areas can intensify poverty and social problems. For example, rapid urban growth can increase urban poverty and inequality, which can increase civil unrest and undermine governments. Crime rates also tend to be higher in urban areas than in rural areas.

However, urban areas have better sanitation, public water supplies, and medical care that have slashed death rates and the prevalence of sickness from malnutrition and transmittable diseases such as measles, diphtheria, typhoid fever, pneumonia, and tuberculosis. Urban dwellers have better access to family planning, education, and social services than do people in rural areas. To many environmentalists and urban planners, the primary problem is not urbanization but our failure to make most cities more sustainable and livable.