ESC 301AIR POLLUTION AND NOISE

Atmospheric Structure

• Natural air-pollution• Volcanic activities, forest fires, ocean

and soil emissions• Anthropogenic air pollution

• Such as acid rain, winter smog, photosmog, ozone depletion and global warming

Pollutants and Atmospheric Cleansing

• Air pollutants: gases and aerosols in the atmosphere that have harmful effects

• Level of air pollution determined by:– The amount of pollutants entering the air– The amount of space into which the pollutants

dispersed– Mechanisms that remove pollutants from the air

Major Air Pollutant Sources

Major Air Pollutant Sources

Fossil fuel based power plants: CO2, SO2, NOx, fly-ash, soot

Industry: Chemical industry, petroleum industry, pulp and paper industry, metallurgical industry, cement industry.

The emissions include SO2, NOx, CO, particulate matter, hydrogen sulfide, hydrogen chloride, hydrogen fluoride, all types of volatile organic carbons (VOCs), metal particles.

Incinerators:Conventional combustion gases, particulate matter

including heavy metals, polynuclear aromatic hydrocarbons (PAHs) , polychlorinated hydrocarbons.

Polychlorinated hydrocarbons such as PCDDs and PCDFs and PBCs : toxic and potentiallly mutagenic.

Motor Vehicles:Exhasut gases contain CO2, CO, NOx, traces of

hydrocarbons from unburnt fuel, particulate lead (if gasoline contains tetraethyl lead) , SO2 (if diesel fuel is used), and PM10.

Indoor Pollutants

Radon: an odourless, colourless, tasteless and radioactive gas

Others: CO, NOx, particulate matter , polynuclear aromatic hydrocarbons (PAHs), formaldehyde, asbestos, pesticides.

Major Air Pollutants and Their Sources

• Suspended particulate matter

• Volatile organic compounds

• Carbon monoxide• Nitrogen oxides

• Sulfur oxides• Heavy metals• Ozone• Air toxics

Major Air Pollutants: Primary (see next slide)

• Primary pollutants derived directly from burning fuels and wastes– Particulates– Hydrocarbons– Carbon monoxide– Nitrogen oxides– Sulfur dioxides

Secondary Air Pollutants

• Secondary air pollutants derive from reactions that occur between primary pollutants and other atmospheric chemicals– Ozone– PANs– Acids: sulfuric and nitric

Impacts of Air Pollutants on Human Health

• Chronic: gradual deterioration of a variety of physiological functions over a period of years

• Acute: life-threatening reactions within a period of hours or days

• Carcinogenic: cancer-causing

Impacts of Air Pollutants on Human Health

• Chronic example: lead poisoning• Acute example: death – Bhopal, India• Carcinogenic example: lung cancer

Hazardous Air Pollutants known or suspected carcinogens, compounds causing other serious health effects, such as

reproductive problems or birth defects. usually associated with industrial processes.

metal compounds, hydrocarbons, halogenated organics, pesticides

Lead (Pb )

Lead is regulated both as a criteria pollutant and as a hazardous air pollutant.

Lead is strictly a primary pollutant.

Lead is associated with suspended particulate matter, mainly in the fine mode.

Lead in fine particles has a long atmospheric residence time and deposits broadly over the globe.

Removal of lead from gasoline leads to some control.

Inadequately controlled industrial sources (e.g., lead smelters, battery manufacturing, and waste incineration) lead to lead emissions.

Particulate Matter (PM) is a year-round phenomenon.

Mixture of solid and liquid particlesdifferent origin, size, composition.

Breakdown of rocks, soil, and dust.

Composed of sulfate, nitrate,chloride, carbon, metals.

•Strong correlation between particulate matter levels in ambient air and

mortality

•Suspended particulate matter is also the major contributor to atmospheric

visibility impairment.

Particulate matter is a mixed primary and secondary pollutant.

Coarse particles are mainly primary pollutants,

Secondary processes contribute to fine particulate mass.

Particle control techniques

Filtration mechanisms, including electrostatic precipitation, mechanical

filtration

Particulate Matter

Particulate Matter (PM10 and PM2.5) PM10 standard limits the mass concentration of airborne particles

whose aerodynamic diameter is less than 10 μm.

A newly proposed PM2.5 standard applies to particles with

aerodynamic diameter smaller than 2.5 μm.

The primary health concern with particulate matter is impairment of

the respiratory system.

Particle exposure may have adverse effects on breathing, may

aggravate existing respiratory and cardiovascular disease (e.g.,

asthma), may impair the body's defense mechanisms against foreign

materials, may damage lung tissue, and may con- tribute to premature

mortality.

PM2.5

Fine particles have diameters less than 2.5 microns. PM2.5 are composed of dust, dirt, soot, smoke, and liquid droplets.

Fine particles are formed by:

1. Direct release (fires, exhaust, dust)2. Chemical reaction

SO2+VOC+NOx+NH3+Water+sunlight = PM2.5

Health effects of PM are related to particle size and composition.

Smaller particles travelfurther into the lungs.

Health Effects of Ozone• Ozone acts as a powerful respiratory irritant at the

levels frequently found in most of the nation's urban areas during summer months.

• Ozone exposure may lead to:– Shortness of breath. – Chest pain when inhaling deeply. – Wheezing and coughing. Long-term, repeated exposure to high levels of

ozone may lead to large reductions in lung function, inflammation of the lung lining, and increased respiratory discomfort.

Health Effects of Sulfur Oxides

• Sulfur dioxide not only has a bad odor, it can irritate the respiratory system.

• Exposure to high concentrations for short periods of time can constrict the bronchi and increase mucous flow, making breathing difficult.

• Children, the elderly, those with chronic lung disease, and asthmatics are especially susceptible to these effects.

Sulfur dioxide can also: • Immediately irritate the lung and throat at

concentrations greater than 6 parts per million (ppm) in many people.

• Impair the respiratory system's defenses against foreign particles and bacteria, when exposed to concentrations less than 6 ppm for longer time periods.

• Apparently enhance the harmful effects of ozone. (Combinations of the two gases at concentrations occasionally found in the ambient air appear to increase airway resistance to breathing.)

Health Effects of Nitrogen Oxides

• Short-term exposure at concentrations greater than 3 parts per million (ppm) can measurably decrease lung function.

• Concentrations less than 3 ppm can irritate lungs. • Concentrations as low as 0.1 ppm cause lung

irritation and measurable decreases in lung function in asthmatics.

• Long-term lower level exposures can destroy lung tissue, leading to emphysema.

• Children may also be especially sensitive to the effects of nitrogen oxides.

Health Effects of Hydrocarbons• Hydrocarbons tend to exist as extremely volatile liquids.• Hydrocarbons can come from natural sources and

anthropogenic (man-made) sources.• Many are known as carcinogenic .

Health Effects of Carbon Monoxide (CO)• Carbon monoxide is an odorless, colorless gas.• It is formed when the carbon in fuels does not completely

burn.– Vehicle exhaust contributes roughly 60% of all carbon

monoxide nationwide, and up to 95% in cities• Hemoglobin in the blood reacts with Carbon monoxide and

forms carboxyhemoglobin forms. The oxygen carrying capacity of blood is reduced. Heart and brain damage can occur.

Summary of Pollutants

The Appearance of Smog

Smog is a kind of air pollution. The name is derived from smoke and fog.

Winter Smog

• This type of smog is created by high emissions of sulfur and nitrogen oxides in response to thermal inversion.

• Suspended droplets of sulfuric acid are formed from some of the sulfur dioxide, and a variety of suspended solid particles.

• pH of the wintersmog can reach values below 2 creating very adverse breathing conditions.

• The most infamous example: London, 1952.

Impacts of Smog: Temperature Inversion

Temperature Inversions• Depending on the geographical location, temperature, wind

and weather factors, pollution is dispersed differently. However, this sometimes does not happen and the pollution can build up to dangerous levels.

• A temperature inversion occurs when air close to the Earth is cooler than the air above it. Under these conditions the pollution cannot rise and be dispersed.– Cities surrounded by mountains also experience trapping

of pollutants– Winter inversions are likely to cause particulate and

carbon pollution– Summer inversions are more likely to create smog

Definition of Acid Rain

• Precipitation that has a pH of less than that of natural rainwater (which is about 5.6 due to dissolved carbon dioxide).

• It is formed when sulfur dioxides and nitrogen oxides, as gases or fine particles in the atmosphere, combine with water vapor and precipitate as sulfuric acid or nitric acid in rain, snow, or fog.

Acid Deposition

Causes of Acid Rain

• Natural Sources– Emissions from volcanoes and from biological processes that occur on

the land, in wetlands, and in the oceans contribute acid-producing gases to the atmosphere

– Effects of acidic deposits have been detected in glacial ice thousands of years old in remote parts of the globe

• The principal cause of acid rain is from human sources– Industrial factories, power-generating plants and vehicles– Sulfur dioxide and oxides of nitrogen are released during the fuel

burning process (i.e. combustion)

Effects of Acid Rain

• Harmful to aquatic life – Increased acidity in water bodies– It changes the chemistry of lakes and streams– Stops egg hatching (e.g. fish) – Changes population ratios – Affects the ecosystem

Effects of Acid Rain

• Harmful to vegetation– Increased acidity in soil– Leaches nutrients from soil, slowing plant growth– Leaches toxins from soil, poisoning plants– Creates brown spots in leaves of trees, impeding

photosynthesis

Effects of Acid Rain

• Accelerates weathering in metal and stone structures– e.g. Parthenon in Athens,

Greece; Taj Mahal in Agra, India

Effects of Acid Rain

• Affects human health– Respiratory problems, asthma, dry coughs, headaches and

throat irritations– Leeching of toxins from the soil by acid rain can be

absorbed by plants and animals. When consumed, these toxins affect humans severely.

– Brain damage, kidney problems, and Alzheimer's disease has been linked to people eating "toxic" animals/plants.

Preventive Measures

• Reduce amount of sulfur dioxide and oxides of nitrogen released into the atmosphere– Use less energy (hence less fuel burnt)– Use cleaner fuels– Remove oxides of sulfur and oxides of nitrogen

before releasing• Flue gas desulfurization• Catalytic Converters

Preventive Measures

• Use cleaner fuels– Coal that contains less sulfur– "Washing" the coal to reduce sulfur content– Natural Gas

Preventive Measures

• Flue Gas Desulfurisation (FGD)– Removes sulfur dioxide from flue gas (waste gases)– Consists of a wet scrubber and a reaction tower equipped

with a fan that extracts hot smoky stack gases from a power plant into the tower

– Lime or limestone (calcium carbonate) in slurry form is injected into the tower to mix with the stack gases and reacts with the sulfur dioxide present

– Lime or limestone produces pH-neutral calcium sulphate that is physically removed from the scrubber

– Sulphates can be used for industrial purposes

Preventive Measures

• Use other sources of electricity (i.e. nuclear power, hydro-electricity, wind energy, geothermal energy, and solar energy)– Issue of cost

Reducing the Effects of Acid Rain

• Liming– Powdered limestone/limewater

added to water and soil to neutralize acid

– Used extensively in Norway and Sweden

– Expensive, short-term remedy

Photochemical smog is a mixture of air pollutants including the following:

nitrogen oxides, such as nitrogen dioxide (NO2)

tropospheric ozone (O3)volatile organic compounds (VOCs) peroxyacyl nitrates (PAN) aldehydes (R'O)

PHOTOCHEMICAL SMOG (PHOTOSMOG)

The starting ingredients in the photochemical smog system

nitrogen oxides (mainly NO), volatile organic compounds, VOCs (mainly hydrocarbons), and sunlight.

Secondary pollutants are produced such as

ozone, aldehydes, organic acids, nitrogen dioxide, nitric acid, and

peroxy acetyl nitrate (PAN).

In current practice, control of photochemical smog focuses on reducing

urban and regional ozone concentrations. Standards do not exist for

many of the other pollutants in the photochemical smog system.

Photolytic Reactions

Sunlight initiates atmospheric reactions.

Photolysis reactions generate radicals, species labeled with . They are species with an

unpaired outer-shell electron, making them highly reactive. Photolysis and radicals are

important in air pollution.

Radicals serve as catalysts for such processes. Their atmospheric lifetimes are very short.

They are present at very low concentrations, but they are of great importance in

atmospheric redox reactions.

In photolytic reactions, the energy to break the chemical bonds is supplied by absorption

of a photon of light.

GENERAL KNOWLEDGE ABOUT PHOTOLYTIC REACTIONS

Notation for photolytic reactions:

h : energy of photon h : Planck's constant (6.63 x 10-34 J s) : frequency of light ( = c 1 where c is the speed of light, 3.0 x 108 m s-l, and is

the wavelength).

Because their generation depends on the photolysis of pollutant molecules, radical

concentrations are highest in heavily polluted air during strong sunlight conditions.

The rates of photolytic reactions vary with overall sunlight intensity and wavelength.

In the troposphere, photolysis is caused by light of wavelengths 280 nm < < 730 nm (410 nm < < 650 nm defines the visible range).

Important for photochemical smog formation

Shorter-wavelength light is absorbed by stratospheric ozone and oxygen molecules and does not penetrate to the troposphere.

if the stratospheric ozone is depleted the UV radiation is not held.

Longer-wavelength light has insufficient energy to break chemical bonds.

GENERAL KNOWLEDGE ABOUT PHOTOLYTIC REACTIONS

In the troposphere near the Earth’s surface, ozone forms through the splitting of molecules by sunlight as it does in the stratosphere. However in the troposphere, nitrogen dioxide, not molecular oxygen, provides the primary source of the oxygen atoms required for ozone formation. Sunlight splits nitrogen dioxide into nitric oxide and an oxygen atom.

A single oxygen atom then combines with an oxygen molecule to produce ozone.

Ozone then reacts readily with nitric oxide to yield nitrogen dioxide and oxygen.

.ONOhNO2

32 OO.O

2232 ONOONO

Mechanism of ozone accumulation:

The process described above results in no net gain in ozone.

Concentrations occur in higher amounts in the troposphere than these

reactions alone account for. In the 1950s, chemists discovered that two

additional chemical constitutents of the troposphere contribute to ozone

formation. These constituents are nitrogen oxides and volatile organic

compounds, and they have both natural and industrial sources.

Ozone formation in the troposphere requires both NOx and VOCs. In a

highly simplified version of tropospheric ozone-forming reactions,

OthersOhVOCNO 3X

O3

SUMMARY

Effects of Photochemical Smog

respiratory discomfortmaterial damage by exposure to photochemical smogagricultural crops are harmed, rubber cracks, and some pigments fade.

Chemical kinetic reactions and phase changes produce secondary

pollutants whose effects are worse than the primary emissions.

Effects of Ozone

Oxidizes matterDestroyes vegetationInhalation cause acute and chronic problems of the respiratory tract and lungs.

When ozone levels in the troposphere are too high, the

only practical means of reducing them is to reduce the

emissions of the precursor pollutants.

A key question in VOC and NOx emission control:

How much reduction in nitrogen oxide and organic

emissions must be achieved to control ozone ?

Indoor Air Pollution

INDOOR AIR POLLUTION

Combustion by-products,

Volatile organic compounds (VOCs),

Radon,

Airborne bacteria and viruses,

Molds,

Allergens.

Radon is an invisible, radioactive atomic gas that results from

radioactive decay of some forms of radium that may be found

in rock formations beneath buildings or in certain building

materials themselves.

Radon is probably the most pervasive serious hazard for indoor

air in the United States and Europe, probably responsible for

tens of thousands of lung cancer deaths per annum.

Radon is a very heavy gas and thus will tend to accumulate at

the floor level. Building materials are actually a signicant source

of radon, but very little testing is done for stone, rock or tile

products brought into building sites.

The half-life for radon is 3.8 days indicating that once the

source is removed, the hazard will be greatly reduced within a

few weeks.

Carbon Monoxide

One of the most acutely toxic indoor air contaminants is (CO),

a colorless, odorless gas that is a byproduct of incomplete

combustion of fossil fuels.

Common sources are tobacco smoke, space heaters using

fossil fuels, defective central heating furnaces and automobile

exhaust.

Improvements in indoor levels are systematically improving

from increasing numbers of non-smoking buildings.

By depriving the brain of oxygen, high levels of CO can lead to

nausea, unconsiousness and death.

Asbestos Fibers

Many common building materials used before 1975 contain

asbestos, such as some floor tiles, ceiling tiles, taping muds,

pipe wrap, mastics and other insulation materials. Normally

significant releases of asbestos fiber do not occur unless the

building materials are disturbed, especially by sanding,

drilling or building remodelling. There are particularly

stringent regulations applicable to schools and residences.

Inhalation of asbestos fibers over long exposure times is

associated with increased incidence of lung cancer.

Biological Contaminants

Biological contaminants are mold, mildew, bacteria,

pet dander, dust mites, and pollen.

Some sources are pollen from plants, and bacteria by

people and animals

Central air units if moist can produce molds and

mildews that are then circulated through the house.

Household Products

Organic chemicals in household products are released during use and possibly during storage

Organic chemicals are found in paints, varnishes, cleaning supplies, and disinfectants

Levels of a dozen common pollutants were found to be 2 to 5 times higher in homes then outside.

Increased risk of cancer with high concentration of indoor organic chemicals.

FormaldehydeSources of formaldehyde in the home are: building materials, smoking, and household products

Another big source of formaldehyde is compressed wood (plywood, and particle board)

The rate at which formaldehyde is released from compressed wood can change

Symptoms of exposure to formaldehyde includes watery eyes, burning sensation in the eyes and throat, and nausea

High levels of exposure can trigger an asthma attack

It also may cause cancer in humans

Reduce the formation of pollutants

•Good quality fuel•Modifications in industrial processes and combustion techniques.

Control the emissions into the atmosphere

•Removal of particulate matter : settling chambers, wet scrubbers, cyclone separators, electrostatic precipitators, fabric filters

•Removal of gaseous pollutants: absorbers, adsorbers, catalytic and non-catalytic converters

AIR POLLUTION CONTROL TECHNOLOGIES

Important pollutants in the automotive exhaust gas

Carbon monoxide (CO)

Hydrocarbons

Nitrogen oxides ( NO and N2O)

Reduction Reaction

2NO N2 + O2

2NO2 N2 + 2O2 Pt/Rh

Pt/Rh

Oxidation Reaction2CO + O2 2CO2

CnH2n+2 + mO2 nCO2 + (n+1) H2O

Pt/Pd

Pt/Pd

                                                                                                                  

                              

Location of catalytic converter in a car

•First legal document: 1848, Great Britain•Federal Air Pollution Legislation: 1955, USA•Clean Air Act: 1956, Great Britain

•Turkey : Air Quality Control Act: 1986

AIR POLLUTION LEGISLATION

Normal işletme şartlarında ve haftalık işgünlerindeki işletme Yayıyan Zararlı Madde saatleri için kütlesel Debiler ______________________________ _______________________________ Toz 15 kg/h Kurşun 0.5 kg/h Kadmiyum 0.01 kg/h Talyum 0.01 kg/h Klor 20 kg/h Klorlu Hidrojen ve Gaz Halde Anorganik Klor Bileşikleri 20 kg/h Florlu Hidrojen ve Gaz Halde Anorganik Flor Bileşikleri 1 kg/h Karbon Monoksit 1000 kg/h Kükürt Dioksit 60 kg/h Azot Dioksit 40 kg/h Not: Tablodaki emisyonlar tesisin tamamından yayılan saatlik kütlesel debilerdir.

SOME REGULATIONS

EmissionsEmissionsShort Term Short Term

((g/mg/m33))Long TermLong Term

((g/mg/m33))

SOSO22

Turkey ( general)Turkey ( general) 400400 150150

Turkey ( Industrial regions)Turkey ( Industrial regions) 400400 250250

ParticulatesParticulates

Turkey ( general)Turkey ( general) 300300 150150

Turkey ( Industrial regions)Turkey ( Industrial regions) 400400 200200

NONO22 300300 100100

COCO 30.00030.000 1010..000000

AMBIENT AIR QUALITY STANDARDS

Source : 1986 Air Quality Control RegulationSource : 1986 Air Quality Control Regulation

1990-2000 AIR POLLUTION STATUS OF THE PROVINCES WHERE NATURAL GAS IS UTILIZED

(g/m3)

NOISE POLLUTION

Outside Construction Road traffic Airports Factories

Inside

Phones TVs / Radios Appliances Power tools

SOURCES OF NOISE

Noise Pollution

Exposure to prolong noise affects speech,hearing, general health and behavior.

Noise Levels• intensity• frequency• periods of exposure• duration

Measurement of sound:

Expressed in terms of sound pressure Decibels (dB) are the unit of

measurement on the loudness scale

)m/W( sound reference a of Intensity

)m/W(sound a of Intensitylog 10)dB(ensityint sound lativeRe

2

2

Interference in communication, stress, effcts on sleep, mental illness.

Psychological effects

Nervousness, loss of hearing, effect on blood pressure, heart rate rise.

Physiological effects