Safety Health and Environmental Engineering

Development and Environment Unit-I

SyllabusDevelopment and Environment:• Global and regional environmental

issues, issues of land, water, air and noise pollution

 

Global Environmental Issues

Green House Effect• The Increase in CO2 content of the

environment has been responsible for gradual heating up the globe, by a process called as green house effect. The progressive warming up of the earth’s surface due to blanketing effect of manmade CO2 in the atmosphere is known as green house effect.

Green House Effect

• From sun 3 types of radiations are emitted, ultraviolet rays(< 400 nm), Visible rays ( 400 – 700 nm) and Infrared rays (700 – 1000 nm), of this the visible rays are having maximum intensity i.e. (400 nm to 700nm wavelength). Approx 47 % of the solar radiation is absorbed by water and land surfaces and the remaining rays are radiated back to the atmosphere in the form of Infrared rays (700 nm – 1000 nm). Water vapor and CO2 molecules in atmosphere near earth’s surface absorb the infrared radiations (heat rays) emitted by earth. Thus the net effect causes warming of atmosphere. This effect is called a green house effect.

Principle of Green House Effect• The transparent walls and roofs of the green house

are such that they allow visible sunlight to enter but prevents the entry of long wavelength Infrared radiations to go out.

• Thus the sunlight is absorbed by soil and structure of the green house. It is then re-emitted as heat rays which cannot pass through the glass. The amount of energy in the green house thus increases the warmth of the atmosphere. In similar ways the earth’s atmosphere bottles up the energy of the sun like green house. Here CO2 and water vapor acts like glass windows.

• CO2 and water vapor in the atmosphere transmits short wavelength solar radiations but reflect longer wavelength heat radiations from warm surfaces of the earth. CO2 molecules are transparent to sunlight but not to heat radiations, so they trap and re-enforce the solar heat like a green house

Green House

Green House Gases• Carbon dioxide ( CO2)• Methane ( CH4)• Nitrous oxide ( N2O)• Chlorofluorocarbon (CFC)• Ozone

Sources of Green House Gasses

• Burning of Coal, Oil, Natural Gas in the factories.• Burning of fossil fuels at power stations• Use of Petrol and Diesel from automobiles,

railways, aircrafts etc.• Burning of firewood and deforestation• Tree and plants release carbon as CO2. • Fire in the forests contribute to the release of CO2

Effects of Warming up of Air

• Increase in temperature on earth’s surface will cause more evaporation of surface water.

• Melting of Glaciers (ice mountains)• Rise in Sea Level will wash away

entire countries from Bombay to Boston.

• Shifting of climate zones will occur.

CO2, CH4, N2O, CFC’s, O3, H2O Vapor

Control• Reduce the consumption of fossil

fuels• Use anti pollution devices• Non conventional energy sources

should be developed as a alternate to fossil fuel.

• Prevent deforestation• Planting more trees.

Acid Rain• Acid Rain is a

environmental Problem caused due to rapid industrialization. Acid rain has become invisible threat to rivers, lakes and forests.

• Acid rain means presence of acids in rainwater. The basic component of acid rain are nitric acid, and sulphuric acid.

Causes of Acid Rain• Acid Rain is because of human

activities. Sulphuric acid is formed when (SO2) is discharged from combustion process converts to sulphurtrioxide (SO3) which reacts with the water vapor present in the atmosphere to form sulphuric acid (H2SO4).

The oxides of sulphur and nitrogen are produced by combination of fossil fuels, smelters, power plant, automobile exhausts, domestic fire.

Acid Rain Formation

Effects of Acid Rain• The acid rain damages the leaves of plants and

trees and retard the growth of forest.• Wash out the nutrients from the soil.• Significant reduction of fish population and decease

in aquatic micro organisms.• Damage to Buildings and structural materials.• Corrosion of houses, monuments, statues and

bridges.• The human nervous system, respiratory system and

digestive system may get affected• Acid rain reduces the rate of photosynthesis and

hence growth of plants.

Effects of Acid Rain

Control• Liming of Lakes• Tough laws to reduce acid forming

pollutants, being released in atmosphere.

Ozone Layer Depletion• Ozone layer depletion is mainly

due to Chloro-floro carbons (CFC). Ozone layer prevents the harmful ultraviolet rays from entering in the atmosphere but (CFC) is one of the main ozone eaters and it allows the penetration of harmful ultraviolet rays. Chloro-floro carbon remains in the atmosphere for decades and reacts with the atmospheric chlorine to accelerate the long chain reaction. This chain reaction slowly eats away the oxygen atom which could be used in the formation of ozone.

© NOAA

• Thus it leads to decrease in Ozone concentration which results in reaching of ultraviolet rays to earth surface due to which heat increases to uncomfortable levels and the temperature of earth increases.

Main Ozone layer Depletors

• CFC (Chloro Floro Carbon) The Chlorofloro carbon are less costly, non toxic, and safe to handle material is used in propellants, cleaning solvents, plastic foams, in dry cleaning industries, for sterilizing surgical instruments. Because of wide use of CFC the CFC in the atmosphere is increased and which has caused irreparable damage to our environment.

• Oxides of Nitrogen:- Burning of Fossil fuels and increase in use of nitrogen as a fertilizer are also contributing in destruction of ozone layer.

• Thus in addition to CFC, the oxides of nitrogen also plays an important role in depletion of Ozone.

Mechanism of Ozone Depletion

• The chlorofloro carbons are highly stable and hence they slowly diffuse in the atmosphere. The ultraviolet rays decompose the CFCs and thus free chlorine and fluorine radicals are released In the atmosphere. This chlorine radical released in the atmosphere converts O3 into O2

• Similarly oxides of Nitrogen also depletes the ozone

• CFCl3 CFCL2 + Cl

• Cl + O3 ClO + O2

• ClO + O Cl + O2

• Similarly• NOx + O3 NO2 + O2

UV rays

UV rays

UV rays

UV rays

Oxygen in the Atmosphere

UV radiation+O2

O

O

+

O +O2 O3 (ozone)

UV O3 (ozone)

O +O2

O +O3 (ozone) O2 O2+

O + O2O3 (ozone)

+

heat

+

Cl- “Free Radicals”…

Cl- “free radical”

O3 (ozone)+O2ClO

+

ClO+

O Cl- “free radical”

+O2

Effects of Ozone Depletion

• The damage to ozone layer will result in damage to plants and animals

• For every 2.5 cm increase in the size of ozone hole, there will be 5 – 6 % increase in skin cancer and cataracts.

• Ultraviolet rays may interfere with photosynthesis leading to lower crop yield

• Ultraviolet rays causes genetic changes in DNA, leading to lower crop yield.

Control.• Discourage use of CFCs and NOx• Better alternative for CFC should be

developed.• Reforestation and forest prevention.

© NASA

28.0 million km2 on 25 September 2006

Maximum ozone hole area for 2009 was 24 million km2 on 17 September.

The Dobson unit (DU) is a unit of measurement of atmospheric ozone columnar density, specifically ozone in the stratospheric ozone layer. One Dobson unit refers to a layer of ozone that would be 10 µm (micrometre)

08 January 2014Good news for fans of planet

Earth: hole in the ozone layer may be healing. .

Regional Environmental Issues

Urban Heat Island

Urban Heat Island

Urban Heat Island

• An urban heat island (UHI) is a metropolitan area that is significantly warmer than its surrounding rural areas due to human activities.

•  The temperature difference usually is larger at night than during the day, and is most apparent when winds are weak.

• UHI is most noticeable during the summer and winter. The main cause of the urban heat island effect is from the modification of land surfaces,

Urban Heat Island

Urban Heat Island

• Monthly rainfall is greater downwind of cities, partially due to the UHI. Increases in heat within urban centres increases the length of growing seasons, and decreases the occurrence of weak tornadoes.

• The UHI decreases air quality by increasing the production of pollutants such as ozone, and decreases water quality as warmer waters flow into area streams and put stress on their ecosystems.

Urban Heat Island

Urban Heat Island

• Not all cities have a distinct urban heat island. Mitigation of the urban heat island effect can be accomplished through the use of green roofs and the use of lighter-colored surfaces in urban areas, which reflect more sunlight and absorb less heat.

Green Roofs

Urban Heat IslandCauses• There are several causes of an urban heat

island (UHI). The principal reason for the night time warming is that the short-wave radiation is still within the concrete, asphalt, and buildings that was absorbed during the day, unlike suburban and rural areas. This energy is then slowly released during the night as long-wave radiation, making cooling a slow process.

Urban Heat Island• Two other reasons are changes in the thermal

properties of surface materials and lack of evapotranspiration (for example through lack of vegetation) in urban areas.

• With a decreased amount of vegetation, cities also lose the shade and cooling effect of trees, Materials commonly used in urban areas for pavement and roofs, such as concrete and , have significantly different thermal bulk properties (including heat capacity and thermal conductivity) and surface radioactive properties than the surrounding rural areas.

• This causes a change in the energy balance of the urban area, often leading to higher temperatures than surrounding rural areas.

Urban Heat Island

• Other causes of a UHI are due to geometric effects. The tall buildings within many urban areas provide multiple surfaces for the reflection and absorption of sunlight, increasing the efficiency with which urban areas are heated. This is called the "urban canyon effect".

Urban Heat Island

Urban Heat Island

• Another effect of buildings is the blocking of wind, which also inhibits cooling by convection and pollution from dissipating.

• Waste heat from automobiles, air conditioning, industry, and other sources also contributes to the UHI. High levels of pollution in urban areas can also increase the UHI, as many forms of pollution change the radioactive properties of the atmosphere. 

• As UHI raises the temperature of cities, it will also increase the concentration of ozone in the air, which is a greenhouse gas.

Urban Heat IslandMitigation

The temperature difference between urban areas and the surrounding suburban or rural areas can be as much as 5°C (9°F). Nearly 40 percent of that increase is due to the prevalence of dark roofs, with the remainder coming from dark-colored pavement and the declining presence of vegetation. The heat island effect can be counteracted slightly by using white or reflective materials to build houses, roofs, pavements, and roads, thus increasing the overall albedo of the city.

Urban Heat Island

Urban Heat Island• Relative to remedying the other sources of

the problem, replacing dark roofing requires the least amount of investment for the most immediate return. A cool roof made from a reflective material such as vinyl reflects at least 75 percent of the sun’s rays, and emit at least 70 percent of the solar radiation absorbed by the building envelope. Asphalt built-up roofs (BUR), by comparison, reflect 6 percent to 26 percent of solar radiation.

Urban Heat Island

Urban Heat Island• Using light-colored concrete has proven effective in

reflecting up to 50% more light than asphalt and reducing ambient temperature. 

• Paving with light-colored concrete, in addition to replacing asphalt with light-colored concrete, communities may be able to lower average temperatures.

• However, research into the interaction between reflective pavements and buildings has found that, unless the nearby buildings are fitted with reflective glass, solar radiation reflected off light-colored pavements can increase building temperatures, increasing air conditioning demands.

Light Colored Concrete

Urban Heat Island• A second option is to increase the amount of

well-watered vegetation. These two options can be combined with the implementation of green roofs. Green roofs are excellent insulators during the warm weather months and the plants cool the surrounding environment.

• Air quality is improved as the plants absorb and convert carbon dioxide to oxygen. 

• From the standpoint of cost effectiveness, light surfaces, light roofs, and curb side planting have lower costs per temperature reduction

Urban Heat Island

Urban Heat Island

Light Pollution

• Light pollution, also known as photo pollution or luminous pollution, is excessive, misdirected, or obtrusive artificial light. Pollution is the adding-of/added light itself, in analogy to added sound, carbon dioxide, etc. Adverse consequences are multiple; some of them may not be known yet. Scientific definitions thus include the following:

• Degradation of photic habitat by artificial light.

Light Pollution

• Alteration of natural light levels in the outdoor environment owing to artificial light sources.

• Light pollution is the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light. Indoor light pollution is such alteration of light levels in the indoor environment due to sources of light, which compromises human health.

• Light pollution is the introduction by humans, directly or indirectly, of artificial light into the environment.

Light Pollution

Light Pollution

• Light pollution competes with starlight in the night sky for urban residents, interferes with astronomical observatories, and, like any other form of pollution, disrupts ecosystems and has adverse health effects. Light pollution can be divided into two main types:

• Unpleasant light that intrudes on an otherwise natural or low-light setting

• Excessive light (generally indoors) that leads to discomfort and adverse health effects

• Light pollution is a side effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues

Light Pollution

Light Pollution

Measurement and global effects• False colors show various intensities of

radiation, both direct and indirect, from artificial light sources that reach space

• Measuring the effect of sky glow on a global scale is a complex procedure. The natural atmosphere is not completely dark, even in the absence of terrestrial sources of light and illumination from the Moon. This is caused by two main sources: airglow and scattered light.

Light Pollution

Light Pollution

• At high altitudes, primarily above the mesosphere, there is enough UV radiation from the sun of very short wavelength that ionization occurs. When these ions collide with electrically neutral particles they recombine and emit photons in the process, causing airglow.

Light Pollution

Effects on animal and human health and psychology

Effects on animal and human health and psychology

• Medical research on the effects of excessive light on the human body suggests that a variety of adverse health effects may be caused by light pollution or excessive light exposure,

• Health effects of over-illumination or improper spectral composition of light may include: increased headache incidence, worker fatigue, medically defined stress,  Likewise, animal models have been studied demonstrating unavoidable light to produce adverse effect on mood and anxiety. For those who need to be awake at night, light at night also has an acute effect on alertness and mood

Effects on animal and human health and psychology

Effects on animal and human health and psychology

Disruption of ecosystems

• When artificial light affects organisms and ecosystems it is called ecological light pollution. While light at night can be beneficial, neutral, or damaging for individual species, its presence invariably disturbs ecosystems.

• Light pollution poses a serious threat in particular to nocturnal wildlife, having negative impacts on plant and animal physiology. It can confuse animal navigation, alter competitive interactions, change predator-prey relations, and cause physiological harm. The rhythm of life is orchestrated by the natural diurnal patterns of light and dark, so disruption to these patterns impacts the ecological dynamics

Disruption of Ecosystems

Reduction

Reduction• This kind of LED droplight could reduce

unnecessary light pollution in building interiors

• Reducing light pollution implies many things, such as reducing sky glow, reducing glare, reducing light trespass, and reducing clutter. The method for best reducing light pollution, therefore, depends on exactly what the problem is in any given instance. Possible solutions include:

Reduction

• Utilizing light sources of minimum intensity necessary to accomplish the light's purpose.

• Turning lights off using a timer or occupancy sensor or manually when not needed.

• Improving lighting fixtures, so that they direct their light more accurately towards where it is needed, and with less side effects.

Reduction

Reduction

• Adjusting the type of lights used, so that the light waves emitted are those that are less likely to cause severe light pollution problems. Mercury, metal halide and above all first generation of blue-light LED road luminaries are much more pollutant than sodium lamps: Earth atmosphere scatters and transmits blue light better than yellow or red light. It is a common experience observing "glare" and "fog" around and below LED road luminaries as soon as air humidity increases, while orange sodium lamp luminaries are less prone to show this phenomenon.

• Evaluating existing lighting plans, and re-designing some or all of the plans depending on whether existing light is actually needed.

Reduction

Arsenic PoisoningArsenic Poisoning

Arsenic poisoning is a global problem arising from naturally occurring arsenic in ground water.Arsenic poisoning is a medical condition caused by elevated levels of arsenic in the body. The dominant basis of arsenic poisoning is from ground water that naturally contains high concentrations of arsenic. A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning from drinking water

Arsenic Poisoning

Symptoms

• Symptoms of arsenic poisoning begin with headaches, confusion, severe diarrhoea, and drowsiness. As the poisoning develops, convulsions and changes in fingernail pigmentation called leukonychia striata may occur.

• When the poisoning becomes acute, symptoms may include diarrhoea, vomiting, blood in the urine, cramping muscles, hair loss, stomach pain, and more convulsions. The organs of the body that are usually affected by arsenic poisoning are the lungs, skin, kidneys, and liver.  The final result of arsenic poisoning is coma and death

Arsenic Poisoning

leukonychia striata

Arsenic Poisoning

Arsenic Poisoning• Arsenic is related to heart

disease(hypertension related cardiovascular), cancer, stroke (cerebrovascular diseases), chronic lower respiratory diseases, and diabetes

• Chronic exposure to arsenic is related to vitamin A deficiency which is related to heart disease and night blindness

Drinking Water

• Chronic arsenic poisoning results from drinking contaminated well water over a long period of time. Many aquifers contain high concentration of arsenic salts. The World Health Organization recommends a limit of 0.01 mg/L (10ppb) of arsenic in drinking water. This recommendation was established based on the limit of detection of available testing equipment at the time of publication of the WHO water quality guidelines.

Drinking Water

• More recent findings show that consumption of water with levels as low as 0.00017 mg/L (0.17ppb) over long periods of time can lead to arsenicosis. The World Health Organization asserts that a level of 0.01 mg/L poses a risk of 6 in 10000 chance of lifetime skin cancer risk and contends that this level of risk is acceptable.

• One of the worst incidents of arsenic poisoning via well water occurred in Bangladesh, which the World Health Organization called the "largest mass poisoning of a population in history.

Removal Methods

Removal Methods• Various techniques have been

evolved for Arsenic removal, most frequently using absorbents such as activated carbon, aluminium oxide, co-operative with iron oxide to form sludge’s, sorption onto iron-oxide-coated polymeric materials, Electro coagulation, by nanoparticle .

Removal Methods

Fluoride in Groundwater • Groundwater is the major source for

various purposes in most parts of the world. Presence of low or high concentration of certain ions is a major issue as they make the groundwater unsuitable for various purposes.

Fluoride in Groundwater

Fluoride in Groundwater • Fluoride is one such ion that causes health

problems in people living in more than 25 nations around the world. Fluoride concentration of at least 0.6 mg/l is required for human consumption as it will help to have stronger teeth and bones. Consumption of water with fluoride concentration above 1.5 mg/l results in acute to chronic dental fluorosis where the tooth become coloured from yellow to brown.

Fluoride in Groundwater

Fluoride in Groundwater • Skeletal fluorosis which causes

weakness and bending of the bones also results due to long term consumption of water containing high fluoride. Presence of low or high concentration of fluoride in groundwater is because of natural or anthropogenic causes or a combination of both

Dental Fluorosis

Skeletal Fluorosis

Occurrence of fluoride Aquifer material • Most of the fluoride in groundwater is

naturally present due to weathering of rocks rich in fluoride. Water with high concentration of fluoride is mostly found in sediments of marine origin and at the foot of mountainous areas

Occurrence of fluoride

Volcanic ash • Volcanic rocks are often enriched in fluoride.

Hydrogen fluorine is one of the most soluble gases in magmas and comes out partially during eruptive activity The aerial emission of fluoride in the form of volcanic ash during volcanic eruption reaches the surface by fall out of particulate fluorides and during rainfall. This fluoride from the soil surface will easily reach the groundwater zone along with percolating rainwater.

Volcanic ash

FertilisersFertilisers • Phosphate containing fertilisers add

up to the fluoride content in soil and groundwater It is evident that superphosphate, potash and NPK (Nitrogen Phosphorous Potassium) which are phosphatic fertilisers contain remarkable amount of fluoride

Fertilisers

Health Implications• Health Implications• Intake of fluoride higher than the

optimum level is the main reason for dental and skeletal fluorosis. Depending upon the dosage and the period of exposure fluorosis may be acute to chronic.

Health Implications

Health Implications• when fluoride concentration in drinking water is

below 0.5 mg/l it causes dental carries; fluoride between 0.5 to 1.5 mg/l results in optimum dental health; 1.5 to 4 mg/l causes dental fluorosis; 4 to 10 mg/l induces dental and skeletal fluorosis while fluoride above 10 mg/l results in crippling fluorosis. However, fluorosis results not only due to the presence of high concentration fluoride in drinking water but also depend on other sources such as the dietary habits which enhance the incidence of fluorosis.

Health Implications

Other effects

• Other health disorders that occur due to consumption of high fluoride in drinking water to be muscle fibre degeneration, low haemoglobin levels, deformities in RBCs, excessive thirst, headache, skin rashes, nervousness, neurological manifestations, depression, gastrointestinal problems, urinary tract malfunctioning, nausea, abdominal pain, tingling sensation in fingers and toes, reduced immunity, etc

Health Implications

Fluoride in IndiaIndia • Of the 85 million tons of fluoride

deposits on the earth’s crust, 12 million are found in India .Hence it is natural that fluoride contamination is widespread, intensive and alarming in India.

Fluoride in India

Mitigation MeasuresMitigation Measures• Everybody needs clean water. When

high fluoride in the drinking water source has been identified, it is better to avoid that source and look for other sources

Mitigation MeasuresInsitu-treatment methods • Insitu method aims at directly

diluting the concentration of fluoride (in groundwater) in the aquifer. This can be achieved by artificial recharge. Construction of check dams in, India has helped widely to reduce fluoride concentration in groundwater

Insitu-treatment methods

Mitigation MeasuresExsitu-treatment methods • Numerous exsitu methods are available

for defluoridation of water either at household or community level. Adsorption method involves the passage of water through a contact bed where fluoride is adsorbed on the matrix. Activated charcoal and activated alumina are the widely used adsorbents.

Exsitu-treatment methods

Mitigation Measures• In ion exchange process, when water passes

through a column containing ion exchange resin, the fluoride ions replace calcium ions in the resin.

• Membrane processes is also an ex-situ technique which includes methods called reverse osmosis and electro dialysis. These are advanced techniques which require high cost input

• All these methods have their own advantages and disadvantages. Hence it is necessary to evaluate the prevailing local conditions and cost effectiveness before choosing a particular defluoridation method for an area.

Mitigation Measures

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