G. Urban environments - Urban stress

Urban stress

Urban microclimate

Urban heat island

Urbanization negatively impacts the environment mainly by the production of pollution, the modification of the physical and chemical properties of the atmosphere, and the covering of the soil surface. Considered to be a cumulative effect of all these impacts is the UHI, defined as the rise in temperature of any man-made area, resulting in a well-defined, distinct "warm island" among the "cool sea" represented by the lower temperature of the area’s nearby natural landscape. Though heat islands may form on any rural or urban area, and at any spatial scale, cities are favoured, since their surfaces are prone to release large quantities of heat. Nonetheless, the UHI negatively impacts not only residents of urban-related environs, but also humans and their associated ecosystems located far away from cities.

Source: http://www.urbanheatislands.com/

Source: http://climate.ncsu.edu/edu/k12/.albedo

Causes

It is well-known that the progressive replacement of natural surfaces by builtsurfaces, through urbanization, constitutes the main cause of UHI formation. Natural surfaces are often composed of vegetation and moisture-trapping soils. Therefore, they utilize a relatively large proportion of the absorbed radiation in the evapotranspiration process and release water vapour that contributes to cool the air in their vicinity. In contrast, built surfaces are composed of a high percentage of non-reflective and water-resistant construction materials. As consequence, they tend to absorb a significant proportion of the incident radiation, which is released as heat.

Vegetation intercepts radiation and produces shade that also contributes to reduce urban heat release. The decrease and fragmentation of large vegetated areas such as parks, not only reduces these benefits, but also inhibits atmospheric cooling due to horizontal air circulation generated by the temperature gradient between vegetated and urbanized areas (i.e. advection), which is known as the park cool island effect. On the other hand, the narrow arrangement of buildings along the city’s streets form urban canyons that inhibit the escape of the reflected radiation from most of the three-dimensional urban surface to space. This radiation is ultimately absorbed by the building walls (i.e. reduced sky view factor), thus enhancing the urban heat release. Additional factors such as the scattered and emitted radiation from atmospheric pollutants to the urban area, the production of waste heat from air conditioning and refrigeration systems, as well from industrial processes and motorized vehicular traffic (i.e. anthropogenic heat), and the obstruction of rural air flows by the windward face of the built-up surfaces, have been recognized as additional causes of the UHI effect.

Source: http://www.urbanheatislands.com/

Source: https://www.researchgate.net/figure/220042607_fig3_Fig-3-Types-of-tree-form-shadow-pattern-above-Direct-radiation-control-and-impact-on

MEAN AIR TEMPERATURE IN PARIS, FRANCE AT 22:00 CESTIN SUMMER 2003. 

CREDITS: VITO, PLANETEK.

Source: https://www.gislounge.com/urban-heat-island-analysis/

Impacts

It has been largely demonstrated that cities with variable landscapes and climates can exhibit temperatures several degrees higher than their rural surroundings (i.e. UHI effect), a phenomenon which if increases in the future, may result in a doubling of the urban to rural thermal ratio in the following decades. Hence, assessment of the UHI and strategies to implement its mitigation are becoming increasingly important for government agencies and researchers of many affected countries. 

As it would be expected, the characteristic inclination towards warming of urban surfaces is exacerbated during hot days and heat waves, which reinforces the air temperature increase, particularly in ill-ventilated outdoor spaces or inner spaces of residential and commercial buildings with poor thermal isolation. This increases the overall energy consumption for cooling (i.e. refrigeration and air-conditioning), hence increasing the energy production by power plants, which leads to higher emissions of heat-trapping greenhouse gases such as carbon dioxide, as well as other pollutants such as sulfur dioxide, carbon monoxide and particulate matter. Furthermore, the increased energy demand means more costs to citizens and goverments, which in large metropolitan areas may induce significant economic impacts. On the other hand, UHIs promote high air temperatures that contribute to formation of ozone precursors, which combined photochemically produce ground level ozone.

A direct relationship has been found between UHI intensity peaks and heat-related illness and fatalities, due to the incidence of thermal discomfort on the human cardiovascular and respiratory systems. Heatstroke, heat exhaustion, heat syncope,and heat cramps, are some of the main stress events, while a wide number of diseases may become worse, particularly in the elderly and children. In a similar way, respiratory and lung diseases have shown to be related to high ozone levels induced by heat events. Several of the above mentioned impacts have been addressed by the US EPA (for further information see links in the “External link” section of this website).

The anomalous warm of the city creates relatively low air pressures that cause cooler, rural air to converge on the urban center, thus forcing warm air to ascend (i.e. convection), which at higher altitudes condensates and precipitates. Studies carried out in several cities of the United States such as Atlanta, New York, Chicago and Washington, have shown that urban-induced precipitation and thunderstorm events are mainly initiated by the UHI. Other meteorological impacts of the UHI are associated with reductions in snowfall frecuencies and intensities, as well as reductions in the diurnal and seasonal range of freezing temperatures. Lastly, high temperatures may produce physiological and phenological  disturbances on ornamental plants and urban forests. 

Although in wintertime the UHI can result in energy savings (i.e. winter penalty), there is a great consent among researchers that this benefit is outweighed by the detrimental effects that ocurr in summertime.

Source: http://www.urbanheatislands.com/

Urban outdoor air pollution

Source: http://www.desdemonadespair.net/2012/03/urban-air-pollution-to-become-top-cause.html

Ambient air pollution is a broader term used to describe air pollution in outdoor environments. Urban outdoor air pollution is a more specific term referring to the outdoor air pollution experienced by populations living in urban areas, typically in or around cities.

What are some of the major sources or causes of urban outdoor air pollution?

Both 'mobile' sources (i.e. cars) and 'stationary' sources (i.e. smoke stacks) make significant contributions to urban outdoor air pollution. Some of the major sources include exhaust fumes from vehicles, emissions from manufacturing facilities (i.e. factories) and power generation (i.e. smoke stacks of coal fired power plants). Also in those cities where residential use of coal and wood for cooking and heating is permitted, the emissions from households using these fuels can make an important contribution to the level of urban outdoor air pollution.

Source: http://www.who.int/phe/health_topics/outdoorair/databases/background_information/en/index4.html

Afr: Sub-Saharan Africa; Amr: Americas; Emr: Eastern Mediterranean; Eur: Europe; Sear: South-East Asia; Wpr: Western Pacific; HI: High income; LMI: Low and middle income; PM10: Fine particulate matter of 10 microns or less.

Source: http://www.who.int/phe/health_topics/outdoorair/databases/cities-2011/en/

Go to the urban outdoor air pollution database, by country and city (corrected version)

Source: http://www.slideshare.net/jpcik/semantic-data-layers-in-air-quality-monitoring-for-smarter-cities

Particulate matter

Definition and principal sources

PM affects more people than any other pollutant. The major components of PM are sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. It consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air. The most health-damaging particles are those with a diameter of 10 microns or less, (≤ PM10), which can penetrate and lodge deep inside the lungs. Chronic exposure to particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as of lung cancer.

Air quality measurements are typically reported in terms of daily or annual mean concentrations of PM10 particles per cubic meter of air volume (m3). Routine air quality measurements typically describe such PM concentrations in terms of micrograms per cubic meter (μg/m3). When sufficiently sensitive measurement tools are available, concentrations of fine particles (PM2.5 or smaller), are also reported.

Health effects

There is a close, quantitative relationship between exposure to high concentrations of small particulates (PM10 and PM2.5) and increased mortality or morbidity, both daily and over time. Conversely, when concentrations of small and fine particulates are reduced, related mortality will also go down – presuming other factors remain the same. This allows policymakers to project the population health improvements that could be expected if particulate air pollution is reduced.

Small particulate pollution have health impacts even at very low concentrations – indeed no threshold has been identified below which no damage to health is observed. Therefore, the WHO 2005 guideline limits aimed to achieve the lowest concentrations of PM possible.

Guideline values

PM2.5

10 μg/m3 annual mean

25 μg/m3 24-hour mean

PM10

20 μg/m3 annual mean

50 μg/m3 24-hour mean

In addition to guideline values, the Air Quality Guidelines provide interim targets for concentrations of PM10 and PM2.5 aimed at promoting a gradual shift from high to lower concentrations.

If these interim targets were to be achieved, significant reductions in risks for acute and chronic health effects from air pollution can be expected. Progress towards the guideline values, however, should be the ultimate objective.

The effects of PM on health occur at levels of exposure currently being experienced by many people both in urban and rural areas and in developed and developing countries – although exposures in many fast-developing cities today are often far higher than in developed cities of comparable size.

"WHO Air Quality Guidelines" estimate that reducing annual average particulate matter (PM10) concentrations from levels of 70 μg/m3, common in many developing cities, to the WHO guideline level of 20 μg/m3, could reduce air pollution-related deaths by around 15%. However, even in the European Union, where PM concentrations in many cities do comply with Guideline levels, it is estimated that average life expectancy is 8.6 months lower than it would otherwise be, due to PM exposures from human sources.

In developing countries, indoor exposure to pollutants from the household combustion of solid fuels on open fires or traditional stoves increases the risk of acute lower respiratory infections and associated mortality among young children; indoor air pollution from solid fuel use is also a major risk factor for cardiovascular disease, chronic obstructive pulmonary disease and lung cancer among adults.

There are serious risks to health not only from exposure to PM, but also from exposure to ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2). As with PM, concentrations are often highest largely in the urban areas of low- and middle-income countries. Ozone is a major factor in asthma morbidity and mortality, while nitrogen dioxide and sulfur dioxide also can play a role in asthma, bronchial symptoms, lung inflammation and reduced lung function.

Ozone (O3)

Guideline values

O3

100 μg/m3 8-hour mean

The recommended limit in the 2005 Air Quality Guidelines was reduced from the previous level of 120 µg/m3 in previous editions of the "WHO Air Quality Guidelines" based on recent conclusive associations between daily mortality and lower ozone concentrations.

Definition and principal sources

Ozone at ground level – not to be confused with the ozone layer in the upper atmosphere – is one of the major constituents of photochemical smog. It is formed by the reaction with sunlight (photochemical reaction) of pollutants such as nitrogen oxides (NOx) from vehicle and industry emissions and volatile organic compounds (VOCs) emitted by vehicles, solvents and industry. As a result, the highest levels of ozone pollution occur during periods of sunny weather.

Health effects

Excessive ozone in the air can have a marked effect on human health. It can cause breathing problems, trigger asthma, reduce lung function and cause lung diseases. In Europe it is currently one of the air pollutants of most concern. Several European studies have reported that the daily mortality rises by 0.3% and that for heart diseases by 0.4%, per 10 µg/m3 increase in ozone exposure.

Nitrogen dioxide (NO2)

Guideline values

NO2

40 μg/m3 annual mean

200 μg/m3 1-hour mean

The current WHO guideline value of 40 µg/m3 (annual mean) was set to protect the public from the health effects of gaseous.

Definition and principal sources

As an air pollutant, NO2 has several correlated activities.

• At short-term concentrations exceeding 200 μg/m3, it is a toxic gas which causes significant inflammation of the airways.
• NO2 is the main source of nitrate aerosols, which form an important fraction of PM2.5 and, in the presence of ultraviolet light, of ozone.

The major sources of anthropogenic emissions of NO2 are combustion processes (heating, power generation, and engines in vehicles and ships).

Health effects

Epidemiological studies have shown that symptoms of bronchitis in asthmatic children increase in association with long-term exposure to NO2. Reduced lung function growth is also linked to NO2 at concentrations currently measured (or observed) in cities of Europe and North America.

Sulfur dioxide (SO2)

Guideline values

SO2

20 μg/m3 24-hour mean

500 μg/m3 10-minute mean

A SO2 concentration of 500 µg/m3 should not be exceeded over average periods of 10 minutes duration. Studies indicate that a proportion of people with asthma experience changes in pulmonary function and respiratory symptoms after periods of exposure to SO2 as short as 10 minutes.

The (2005) revision of the 24-hour guideline for SO2 concentrations from 125 to 20 μg/m3 was based on the following considerations.

• Health effects are now known to be associated with much lower levels of SO2 than previously believed.
• A greater degree of protection is needed.
• Although the causality of the effects of low concentrations of SO2 is still uncertain, reducing SO2 concentrations is likely to decrease exposure to co-pollutants.

Definition and principal sources

SO2 is a colourless gas with a sharp odour. It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores that contain sulfur. The main anthropogenic source of SO2 is the burning of sulfur-containing fossil fuels for domestic heating, power generation and motor vehicles.

Health effects

SO2 can affect the respiratory system and the functions of the lungs, and causes irritation of the eyes. Inflammation of the respiratory tract causes coughing, mucus secretion, aggravation of asthma and chronic bronchitis and makes people more prone to infections of the respiratory tract. Hospital admissions for cardiac disease and mortality increase on days with higher SO2 levels. When SO2 combines with water, it forms sulfuric acid; this is the main component of acid rain which is a cause of deforestation.

Source: http://www.who.int/mediacentre/factsheets/fs313/en/

Source: http://www.slideshare.net/jpcik/semantic-data-layers-in-air-quality-monitoring-for-smarter-cities

Other types of environmental and social stress

Traffic congestion

Source: http://oppositelock.kinja.com/people-who-think-small-cars-are-the-answer-to-city-traf-1644139527

Causes

• The 'car culture'. e.g. Los Angeles, USA.
• Poor or lack of planning of city roads. e.g. Dhaka, Bangladesh.
• Inefficient and/or inadequate public transport. e.g. Sao Paulo, Brazil.
• Overpopulation. Beirut, Lebanon.

Effects

Delays

The first thing many people think of when it comes to congested roadways is the delay. During the morning commute there is additional stress because delays caused by traffic can make people late for work. And at the end of the day, the afternoon rush hour is again a frustrating time because the workday is done and people want to get home to relax, and traffic is preventing it. These delays are the effects most people feel because they are universal to everyone who has to maneuver through congested roads.

"Just In Case" Time

A secondary effect of traffic congestion related to delays is the inability to estimate travel times. Those who regularly travel congested areas know approximately how long it usually takes to get through a particular area depending on the time of day or the day of the week. These experienced city drivers have to build in time "just in case" the traffic is bad. This takes away from leisure time and time to do other tasks throughout the day. Also, on a day when the traffic is unusually light the built in extra time may be of no use and the person arrives too early.

Fuel Consumption And Pollution

The stopping and starting in traffic jams burns fuel at a higher rate than the smooth rate of travel on the open highway. This increase in fuel consumption costs commuters additional money for fuel and it also contributes to the amount of emissions released by the vehicles. These emissions create air pollution and are related to global warming.

Road Rage

Road rage is a senseless reaction to traffic that is common in congested traffic areas. If someone is not driving as fast as the person behind him thinks he should, or someone cuts in front of someone else it can lead to an incident that is dangerous to the offender and those around him on the road. Road rage often manifests itself as shouting matches on the road, intentional tailgating, retaliatory traffic maneuvers and mostly a lack of attention being paid to the traffic around the people involved. It is basically a temper tantrum by frustrated drivers in traffic.

Emergency Vehicles

When you dial 911 and request a police officer, an ambulance or a fire truck and the emergency vehicle is unable to respond in an appropriate amount of time because of traffic congestion it can be a danger to you and your property. Systems are available that help alleviate the problem by allowing the emergency crews to automatically change the traffic lights to keep the line moving.

Source: http://traveltips.usatoday.com/effects-traffic-congestion-61043.html

Overcrowding

Source: https://br.pinterest.com/pin/295196950547565732/

The promise of jobs and prosperity, among other factors, pulls people to cities. Half of the global population already lives in cities, and by 2050 two-thirds of the world's people are expected to live in urban areas. But in cities two of the most pressing problems facing the world today also come together: poverty and environmental degradation.

Poor air and water quality, insufficient water availability, waste-disposal problems, and high energy consumption are exacerbated by the increasing population density and demands of urban environments. Strong city planning will be essential in managing these and other difficulties as the world's urban areas swell.

Threats

• Intensive urban growth can lead to greater poverty, with local governments unable to provide services for all people.
• Concentrated energy use leads to greater air pollution with significant impact on human health.
• Automobile exhaust produces elevated lead levels in urban air.
• Large volumes of uncollected waste create multiple health hazards.
• Urban development can magnify the risk of environmental hazards such as flash flooding.
• Pollution and physical barriers to root growth promote loss of urban tree cover.
• Animal populations are inhibited by toxic substances, vehicles, and the loss of habitat and food sources.
• Shortage of housing (Source: Codrington, Stephen B. Planet Geography. Adelaide: Solid Star Press, 2002. Print.)

Solutions

• Combat poverty by promoting economic development and job creation.
• Involve local community in local government.
• Reduce air pollution by upgrading energy use and alternative transport systems.
• Create private-public partnerships to provide services such as waste disposal and housing.
• Plant trees and incorporate the care of city green spaces as a key element in urban planning.

Source: http://environment.nationalgeographic.com/environment/habitats/urban-threats2/

Noise

Source: https://en.wikipedia.org/wiki/Noise_pollution

Sources of Urban Noise

Cities have many sources of noise; many of the more significant and preventable sources arise from traffic and industry. Motor vehicle traffic is usually the single greatest contributor of noise in most cities.

TRAFFIC

Motor vehicle noise, including noise from automobiles, motorcycles, buses, and trains, is a result of  (1) vehicle traction systems including the engine, braking, exhaust (2) the interface of the wheel and the road or rail and (3) displacement of air, which is important at high speeds. 

While modern vehicle are designed to limit noise, some people make illegal modifications to exhaust systems, which are designed to create obnoxious noise.

Traffic noise disproportionately affects residents living near highways and freight and transit routes A heavy truck will produce approximately twenty to thirty times more sound energy than a personal automobile.

Emergency response vehicles are problematic sources of noise for residents living near hospitals or police and fire stations. 

Public sanitation vehicles make loud noises when picking up or compacting refuse.

Alarms and back-up beepers are relatively new but highly obnoxious forms of traffic noise and are largely unregulated.

Traffic noise is not inevitable; cities can minimize traffic noise by maintaining roads, constructing sound barriers, reducing vehicle speeds, enforcing illegal vehicle modifications, carefully routing freight trucks, choosing electric buses, and increasing the use of public transit, bicycles, and walking.

INDUSTRY

Many noise complaints result from proximity of housing to businesses, industries, and institutional uses.

Residential-industrial noise conflicts arise from mechanical equipment, loading and unloading of delivery vehicles, heavy truck backup beepers, generators, and refrigeration equipment.

Mechanical ventilation systems, particularly those on rooftops can be a significant annoyance if there is an adjacent residential building that is higher. 

Modern construction involves diesel powered heavy equipment, loud electric and pneumatics tools and frequent freight delivery

Powered equipment, like gas powered leaf blowers used for property maintenance is a common source of noise annoyance.

Thoughtful planning and building rules and their strict enforcement can mitigate many noise conflicts.  Zoning codes can limit the incompatible proximal location of residential and commercial uses.  Building code can require acoustical insulation to keep sound inside bars and clubs and to keep living and sleeping areas quite while adequately ventilated.

Health Effects of Noise

Chronic exposure to elevated levels of community noise creates significant health risks.  These health impacts of noise depend on the intensity of noise, on the duration of exposure, and the context of exposure.   

Noise annoyance is defined as “a feeling of resentment, displeasure, discomfort, dissatisfaction, or offense when noise interferes with someone's thoughts, feelings, or actual activities”

Moderate levels of noise can limit or interfere with the ability to conduct daily tasks and activity — to have an ordinary conversation, enjoy a leisure activities, rest, sleep, concentrate or get tasks done.

Noise from moderate levels of road traffic impairs cognitive functioning in children, including attention, concentration, sound discrimination, memory, and reading ability.  Some children exposed to moderate levels of road traffic noise develop deficits in reading ability and suffer lower school in school performance.

Noise interferes with sleep. Noise can make it difficult to fall asleep, and abrupt noises can cause awakenings, which the sleeper may not sense or recall.  Even at levels below which awakening may occur, noise produces measurable physiological reactions, such as increase in heart rate and body movements and can cause disturbances of natural sleep patterns by causing shifts from deep to lighter stages. People affected by noise may get up "tired" or "not rested" in the morning.

Sleep disturbance can begin at relatively modest noise levels (40 dB). At the level of noise produced by a busy road, the proportion affected by sleep disturbance becomes significant.  Average nighttime noise level of 65 dB will result in self-reported disturbance of sleep in about 15% percent of the population. A single noise event at 80 DB will result in awakenings in about a third of the population.

Noise is a biological stressor; it triggers autonomic chemical mechanisms for arousal and alertness. Consequentially, noise may cause or aggravate conditions related to chronic stress.

While evidence is not yet conclusive, exposure to higher levels road traffic noise is associated with higher a risk for myocardial infarction and exposure air traffic noise is  associated with hypertension.

ACTIONS CITIES CAN TAKE TO MINIMIZE NOISE IMPACTS

INCOMPATIBLE LAND USES

 

Businesses including markets, restaurants, bars, shops, and auto services can generate noise conflicts because of delivery vehicles, ventilation or refrigeration equipment, the use of powered machines and tools, and musical equipment.

 

Cities can implement zoning controls and other land use policies to  limit or avoid the proximity of noisy and noise-sensitive uses.

Source: http://earthjournalism.net/resources/noise-pollution-managing-the-challenge-of-urban-sounds

CONSTRUCTION

 

Construction can be noisy because of heavy equipment such as pile drivers and bulldozers, as well as saws, jackhammers, and trucks, particularly when it occurs during evening and morning hours.

 

Cities can implement and enforce policies limiting the use of construction equipment at night.

Cities can require quiet equipment when construction occurs at night or near sensitive uses, such as hospitals.

TRAFFIC NOISE

 

Traffic is the single most important contributor to background noise levels inmost urban areas. 

Trucks, buses, and trams are much louder than other vehicles. 

Vehicles that clean streets and collect refuse and recyclables, and compost often operate in the early morning hours.

 

Federal and State agencies limit how much the noise may be emitted by motor vehicle engines; however, no laws limit the number of vehicles on a street or the times they operate.

Municipalities can purchase quieter public service and transit vehicles (e.g. electric and hybrid buses). They can also monitor and regulate private refuse service vehicles.

Control of vehicle speed and maintenance of  streets can limit general traffic noise.

Local regulations can limit the use of vehicle alarms and back up beepers .

MACHINERY AND EQUIPMENT

 

Commercial and residential buildings have fixed mechanized and powered equipment for either operation of a business or for ventilation, air conditioning, refrigeration, transport, and other needs.

 

Cities can ensure machinery and equipment installed in new buildings are as quiet as possible.

Cities can implement and enforce noise standards for loud machinery and equipment and can restrict on the use, location, or timing of specific equipment or activities to protect health and sleep.

PROTECTION OF RESIDENTIAL INTERIORS

 

Noise in residential interiors can come from sources within the building such as other occupants or building systems, or from external sources such as traffic and nearby businesses.

 

Cities can adopt building standards to require quiet interiors (e.g. 55 dBA Day and 40dbA Night).

Cities can monitor and enforce noise standards in residential areas

Subsidize acoustical retrofits (e.g. double pane windows, mechanical ventilation) for existing residential buildings near traffic noise sources.

ENTERTAINMENT

 

Amplified sound systems in bars, restaurants, and clubs generate significant noise.

Outdoor gatherings and events  at stadiums and entertainment venues are often disruptive to surrounding neighborhoods.

 

 

Cities can permit and monitors entertainment venues requiring building insulation and limiting hours of operation.

Cities can permit and regulate outdoor public events to limit noise impacts.

Source: http://earthjournalism.net/resources/noise-pollution-managing-the-challenge-of-urban-sounds

Depletion of green space

Source: http://blogdadani-se.blogspot.com.br/2014_01_01_archive.html

Definition:

The depletion of green space involves the use of natural, environmentally friendly land for other developmental causes 

e.g. new factories, industrial buildings, offices, tourist attractions 

Causes:

• Limited spacing 

Some areas in the world are overpopulated and the land available is small. Thus, the supply of land is increased through centrifugal expansion of the urban areas.

• Increased demand for housing

Due to the large population of some areas in the world and limited land (e.g. Lagos and Hong Kong), the demand and price for housing is significant. This can cause the construction of more housing spaces in nearby Greenfield sites.

Effects and Impacts:

Effects of having green space Effects of depleting the green space

Improved ecology/environment of the urban area Destruction of natural habitat

Improvement in quality of environment Loss of species and habitat of animals and plants

Creates job opportunities Building on greenfield sites leads to the need for transport, facilities, etc. 

Growth of businesses within the company (especially tourism)

Managing these Issues:

To manage the issues of green space depletion, there are multiple things that can be done to preserve or create a better environment especially for urban areas.

These methods include:

• Building public parks

• Awareness campaigns for green space preservation and protection

• Awareness campaigns for the damage done through the depletion of green space.

Source: https://www.google.com.br/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwj0hOOVj_3NAhWHxpAKHav0BH4QFghBMAA&url=https%3A%2F%2Fmrphillipsibgeog.wikispaces.com%2Ffile%2Fview%2Fdepletionofgreenspace_infosheet.docx&usg=AFQjCNFw4uqeWSnb-eyn1BY2J9ohLPwtbg&bvm=bv.127178174,d.Y2I

Waste overburden

Source: http://urbanomnibus.net/2014/02/on-waste/

Rapid population growth and urbanization in developing countries has led to people generating enormous quantities of solid waste and consequent environmental degradation. The waste is normally disposed in open dumpscreating nuisance and environmental degradation. Solid wastes cause a major risk to public health and the environment. Management of solid wastes is important in order to minimize the adverse effects posed by their indiscriminate disposal.

Types of solid wastes: Depending on the nature of origin, solid wastes are classified into

URBAN OR MUNICIPAL WASTES

INDUSTRIAL WASTES and

HAZARDOUS WASTES

SOURCES OF URBAN WASTES

Urban wastes include the following wastes:

Domestic wastes containing a variety of materials thrown out from homes

Ex: Food waste, Cloth, Waste paper, Glass bottles, Polythene bags, Waste metals, etc.

Commercial wastes: It includes wastes coming out from shops, markets, hotels, offices, institutions, etc.

Ex: Waste paper, packaging material, cans, bottle, polythene bags, etc.

Construction wastes: It includes wastes of construction materials.

Ex: Wood, Concrete, Debris, etc.

Biomedical wastes: It includes mostly waste organic materials

Ex: Anatomical wastes, Infectious wastes, etc.

Classification of urban wastes

Urban wastes are classified into:

Bio-degradable wastes - Those wastes that can be degraded by micro organisms are called bio-degradable wastes

Ex: Food, vegetables, tea leaves, dry leaves, etc.

Non-biodegradable wastes: Urban solid waste materials that cannot be degraded by micro organisms are called non-biodegradable wastes.

Ex: Polythene bags, scrap materials, glass bottles, etc.

SOURCES OF INDUSTRIAL WASTES

The main source of industrial wastes are chemical industries, metal and mineral processing industries.

Ex:

Nuclear plants: It generated radioactive wastes

Thermal power plants: It produces fly ash in large quantities

Chemical Industries: It produces large quantities of hazardous and toxic materials.

Other industries: Other industries produce packing materials, rubbish, organic wastes, acid, alkali, scrap metals, rubber, plastic, paper, glass, wood, oils, paints, dyes, etc.

EFFECT OF IMPROPER SOLID WASTE MANAGEMENT

1. Due to improper disposal of municipal solid waste on the roads and immediate surroundings, biodegradable materials undergo decomposition producing foul smell and become a breeding ground for disease vectors.
2. Industrial solid wastes are the source for toxic metals and hazardous wastes that affect soil characteristics and productivity of soils when they are dumped on the soil
3. Toxic substances may percolate into the ground and contaminate the groundwater.
4. Burning of industrial or domestic wastes (cans, pesticides, plastics, radioactive materials and batteries) produce furans, dioxins and polychlorinated biphenyls that are harmful to human beings.

Solid waste management involves waste generation, mode of collection, transportation, segregation of wastes and disposal techniques.

DISCARDING WASTES:

The following methods are adopted for discarding wastes:

• Landfill
• Incineration and
• Composting

LANDFILL: Solid wastes are placed in a sanitary landfill in which alternate layers of 80 cm thick refuse is covered with selected earth-fill of 20 cm thickness. After 2-3 years solid waste volume shrinks by 25-30% and land is used for parks, roads and small buildings. This is the most common and cheapest cheapest method of waste disposal and is mostly employed in Indian cities.

Advantages:

It is simple and economical

Segregation of wastes is not required

Landfilled areas can be reclaimed and used for other purposes

Converts low-lying, marshy waste-land into useful areas.

Natural resources are returned to soil and recycled.

Disadvantages:

Large area is required

Land availability is away from the town, tansportation costs are high

Leads to bad odour if landfill is not properly managed.

Land filled areas will be sources of mosquitoes and flies requiring application of insecticides and pesticides at regular intervals.

Causes fire hazard due to formation of methane in wet weather.

INCINERATION:

It is a hygenic way of disposing solid waste. It is suitable if waste contains more hazardous material and organic content. It is a thermal process and very effective for detoxification of all combustible pathogens. It is expensive when compared to composting or land-filling.

In this method municipal solid wastes are burnt in a furnace called incinerator. Combustibe substances such as rubbish, garbage, dead organisms and non-combustibe matter such as glass, porcelain and metals are separated before feeding to incinerators. The non-combustible materials can be left out for recycling and reuse. The leftover ashes and clinkers may account for about 10 to 20% which need further disposal by sanitary landfill or some other means.

The heat produced in the incinerator during burning of refuse is used in the form of steam power for generation of electricity through turbines. Municipal solid waste is generally wet and has a high calorific value. Therefore, it has to be dried first before burning. Waste is dried in a preheater from where it is taken to a large incinerating furnace called "destructor" which can incinerate about 100 to 150 tonnes per hour. Temperature normally maintained in a combustion chamber is about 700 C which may be increased to 1000 C when electricity is to be generated.

ADVANTAGES

Residue is only 20-25% of the original and can be used as clinker after treatment

Requires very little space

Cost of transportation is not high if the incinerator is located within city limits

Safest from hygenic point of view

An incinerator plant of 3000 tonnes per day capacity can generate 3MW of power.

DISADVANTAGES

Its capital and operating cost is high

Operation needs skilled personnel

Formation of smoke, dust and ashes needs further disposal and that may cause air pollution.

COMPOSTING

It is another popular method practiced in many cities in our country. In this method, bulk organic waste is converted into fertilizer by biological action.

Separated compostible waste is dumped in underground trenches in layers of 1.5m and finally covered with earth of 20cm and left for decomposition. Sometimes, actinomycetes are introduced for active decomposition. Within 2 to 3 days biological action starts. Organic matter is destroyed by actinomycetes and lot of heat is liberated increasing the temperature of compost by 75C and the refuse is finally converted into powdery brown coloured odourless mass called humus that has a fertilizing value and can be used in agriculture. Humus contains lot of Nitrogen essential for plant growth apart from phosphates and other minerals.

ADVANTAGES

Manure added to soil increases water retention and ion-exchange capacity of soil.

This method can be used to treat several industrial solid wastes.

Manure can be sold thereby reducing cost of disposing wastes

Recycling can be done

DISADVANTAGES

Non-consumables have to be disposed separately

The technology has not caught-up with the farmers and hence does not have an assured market.

Source: http://mjcetenvsci.blogspot.com.br/2013/11/thermal-pullution-source-effects-and.html

Poor quality housing

Source: http://www.ipsnews.net/2008/04/rights-cambodia-property-boom-forces-evictions-of-urban-poor/

Although urban sprawl has occurred in many cities in developing countries, average population densities are still higher than in most cities in Europe, Australia and North America. Rapid population growth has led to overcrowding, which can be defined as too many people occupying too little space and competing for too few services or jobs.

One of the main consequences of overcrowding is a shortage of housing, a characteristic of every city in every LEDC. Although some cities have pavement dwellers, the more common evidence of the housing shortage is shanty settlements with possibly no building or sanitation standards.  The lack of basic services such as water and sewage may lead to health problems and the spread of diseases.

Source: Codrington, Stephen B. Planet Geography. Adelaide: Solid Star Press, 2002. Print.

Some causes of urban overcrowding/sprawl leading to the existence of poor quality housing are:

• Population growth
• Economic growth 
• Industrialization
• Speculation
• Legal disputes
• Physical geography
• Urban development
• Taxes
• Living and property cost
• Lack of affordable options for housing
• Demand for more living space
• Public regulation
• Lack of transportation
• (Lack of) urban planning

Source: Bhatta, B. Analysis Of Urban Growth And Sprawl From Remote Sensing Data. Heidelberg: Springer, 2010. Print.

Improving housing policy to help the urban poor: an expanded goal for the post-2015 agenda

Social deprivation, crime and inequality

Source: http://www.dailymail.co.uk/news/article-2281567/Nearly-half-children-Britains-deprived-urban-areas-living-poverty-line-new-report-reveals.html

Decay & deprivation is a relative concept depending on how deprived the area is in relation to more prosperous areas.

Inner city areas suffer

Poverty

Pollution

Crime

Overcrowding

Poor housing conditions

Unemployment

Racial tension

Causes of Deprivation

Inner city areas were once thriving communities with a mixture of land-use and rich living alongside poor. There were shops & houses, services, community spirit & little crime. However there were high levels of pollution – land, air & water. Poor sanitation led to a high death rate.

Cycle of deprivation

After the industrial revolution people became increasingly affluent. This led to social segregation – rich move out of inner city to the suburbs. People left in the inner city:

Older residents

Single parent families

Students

Poorer families

Ethnic minorities left behind – formation of ghettos.

Decentralisation increases the problem: 

Movement of businesses out of inner city – unemployment – Dead Heart.

Removal of businesses causes a loss of money from the area so there is little money available to invest in improvements.

Out-of-town shopping centres means less wealthy are deprived of better shops – less mobile.

Inner city Problems

Social Problems

Properties have deteriorated

High percentage of overcrowded households

Higher death & infant mortality rates

Lower life expectancy

Social segregation – Racial discrimination e.g. Brixton. People are socially excluded.

Persistent unemployment – culture of poverty

High levels of stress due to poverty – family breakdowns.

Economic problems

Loss of business & industry – massive unemployment (51% above national average.

Few people can afford to own their own houses or invest any money.

Local authorities have little taxes so lack of investment in the local area.

Environmental decay – spiral of decline.

Businesses put off by high land prices, lack of space, high crime & traffic congestion.

Environmental Problems

Decay & deprivation of factories – seedbeds for crime e.g. drugs.

Lack of open space

Dereliction and poor state of repair causes depressing environment.

Air pollution

Local watercourses often badly polluted by factories.

Overall the problem was so bad that there was multiple deprivation due to huge number of different problems that the areas face. There were numerous initiatives to try to stop deterioration.

Source: http://www.thestudentroom.co.uk/wiki/Revision:Urban_Deprivation_in_MEDCs

Causes of Urban decline.

1.     Political decisions – governments can favour some cities over others, and encourage the development of some areas over others.  London is a city that attracts lots of investment, but the UK government has tried to decentralise some of its functions.

2.     Another cause is the outmigration of wealthier and more skilled people leaves a lesser qualified population. Often tied in with Suburbanisation, this removes people who are better off economically, leaving the area to those who are usually poorer, which contributes to higher unemployment rates, a characteristic of urban decay. In the USA this has become known as “White flight”, as the white middle class gradually left the cities for suburban areas because of the perceived higher crime rates and danger caused by African-American migration north toward cities after World War I

Decline in Quality of housing stock - The old pre-war buildings get worse because of poor maintenance because the owners are unwilling to spend money on maintenance or because the tenants cannot afford to spend money on maintenance. The stock can also decline in quality if population densities become too high. In Byker, poor quality housing stock resulted in poor living conditions for residents and had to be replaced.

There was lack of urban planning in the past. Things such as narrow streets cause traffic congestion and can force people and investment away. This happened in the London Docklands where traffic into and out of the Docklands was initially limited for security reasons, and later became a reason for lack of investment because of poor communications.

5.     The loss of an industry through changing market conditions or a lack of/withdrawal of government support. This has happened in the UK, such as Scotswood in Newcastle or large parts of Middlesbrough.  In the USA many of the heavy manufacturing industries were located in the North of the country in cities such as Chicago and Detroit.  This has become known as the “Rust Belt” as globalisation and out sourcing of many industries to low wage Asian countries has decimated those industries. In cities like Detroit, entire neighbourhoods have been abandoned as high paying manufacturing jobs vanished and the workers along with them. Rust belt to sun-belt migration has also occurred, with people moving to warmer climates in the South of the USA.

The concentration of low income groups in one area of a city can lead to urban decay because of poverty.. The residents in the inner city are often low-income group (or new immigrants) for easy access to work. This carries with it social issues. Indeed, high levels of poverty can result in higher drug use and increase the level of crime, which contributes to urban decay. When crime levels go up, property prices decrease, leading to higher levels of building disrepair and eventual abandonment

Racism and a lack of ethnic integration.  In the past in some countries people were discriminated against because of their race.  In the USA African-Americans were most likely to be declined jobs and loans, both of which would help their economic status as well as the health of their neighbourhoods. Discrimination can therefore promote unemployment, which in turn promotes poverty, street gangs and illegal drug-trafficking activities and other crimes. In the UK this did not occur in the same OVERT way, but ethnic segregation and poor integration can occur, particularly when incoming migrants groups are poor and cluster in poorer districts. This stifles growth in these areas and can promote decay.

Source: http://www.coolgeography.co.uk/A-level/AQA/Year%2013/World%20Cities/Decline/Urban_Decline.htm