Faculty of allied medical science Environmental health (NREH-101)

Faculty of allied medical science

Environmental health(NREH-101)

Air pollution

SupervisionProf.dr/Mervat Salah

Outcomes

1-To know the meaning of air pollution2-To differentiate between outdoor and indoor pollution3-To know types of air pollution4-To understand the ways to control air pollution

AIR POLLUTIONType of Air pollution:- outdoor pollution – indoor pollution

Sources of out door pollution Combustion of fuel (natural gas, petroleum, coal and

wood)

Industrial process

Natural process (Volcanic)

Carbon oxides (CO)

Nitrogen oxides and nitric acid (NO, HNO3)

Sulfur dioxide and sulfuric acid (SO2, H2SO4)

Particulates (SPM)

Ozone (O3)

Volatile organic compounds (VOCs)

)

Types of Major Air Pollutants

Pollutants Pollutants can be classified as either primary or secondary- Primary pollutants are substances directly emitted from a process, such

as the carbon monoxide gas from a motor vehicle exhaust or sulfur dioxide released from factories.

- Secondary pollutants are not emitted directly. Rather, they form in the

air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone

Sources and Types of Air Pollutants

Environmental challenges

• Green house effect: Increasing global temperature. Scientists predicting that earth's temperature will increase by 3-40C by year 2030 if the pollution continues to increase at the same pace.

• Ozone depletion: As ozone layer in the upper

atmosphere absorbs incoming harmful ultraviolet radiation but it is now getting thinner & more UVs are reaching in to earth creating different disease like cancer& eye problems.

• Photochemical smog: In 1952 London was covered by smog for 10 days .This smog was caused by fog, smoke, ash,& SO2 plus NO2.Sunlight played a great role in the formation of this smog .

Acid rain: is caused by oxides of nitrogen & sulphur.It increases acidity of soil & effects the growth of trees & plants.

Acid Deposition• Sulfur dioxides and nitrogen oxides• Wet and dry deposition• Acid rain• Regional air pollution

– Midwest coal-burning power plants– Prevailing winds

Fig. 15-4, p. 351

Lakes in deepsoil high in limestoneare buffered

Lakes in shallow soillow in limestonebecome acidic

Wet acid deposition(droplets of H2SO4 andHNO3 dissolved in rainand snow)

Dry acid deposition(sulfur dioxide gasand particles ofsulfate and nitrate salts)

Windborne ammonia gasand some soil particles partiallyneutralize acids and form drysulfate and nitrate salts

Sulfur dioxide(SO2) and NO

Nitric oxide (NO)

Acid fog

Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3)

Wind

Acid Deposition

Effects Of Pollution

• Respiratory diseases in human

• Toxic metal leaching

• Structural damage

• Kills fish and other aquatic organisms• Leaches plant nutrients from soil

• Acid clouds and fog at mountaintops

Acid Rain

SO2 & NOX

+water

SEASeaLakeFactories,

Transportation

Solar Radiation

H2SO4 (Sulphuric Acid)

HNO3 (Nitric Acid)

The Greenhouse Effect

Earth’s natural greenhouse effect

Natural greenhouse gasesWater vapor (H2O)Carbon dioxide (CO2)Methane (CH4)Nitrous Oxide (N2O)

Enhanced greenhouse effect Global warming

Effect of Global warming• Rise in average global surface temperature• Changes in glaciers, rainfall patterns,

hurricanes• Droughts and floods. Threat to biodiversity• Decreased food production• Diseases (Threats to human health)• Economic and social disruption

• Rising sea levels• Extreme weather

Government Roles in Reducing the Threat of Climate Change (1)

• Regulate carbon dioxide as a pollutant

• Carbon taxes

• Cap total CO2 emissions

• Subsidize energy-efficient technologies

• Technology transfers

Photochemical reactions

Photochemical smogBrown-air smog

Sources

Climate effects

Urban areas

Photochemical Smog

A

Methane

Carbon Dioxide

Nitrous oxide

Ozone

EarthEarth

Carbon Dioxide

50%

Methane 18%

Chlorofluorocarbons

14%

Ozone 12%

Nitrous oxide

06%Green house gases in natural condition insulates the earth against extreme of temperature by limiting both incoming solar radiation & escape of reradiated heat in to space.

This natural balance may be distorted by Green House Effect as gases such as carbon dioxide have built up in the atmosphere trapping more heat

sun

Infra-red radiation

Atmosphere

Surface Temperature normal

Some reradiated heat reflected back to earth

Atmosphere

sun

Surface Temperature increases

More reradiated heat reflected back to earth

Less reradiated heat escapes in to space

Some reradiated heat escapes in to space

sun

Contribution of different gases to cause green house effect

H2O WaterNO2

Nitrogen dioxide

Hydrocarbons

O2

Molecular Oxygen

HNO3 Nitric Acid

PANs Peroxyacyl nitrates

Aldyhydes (e.g. Formaldehyde)

O3

Ozone

O Atomic Oxygen

NO Nitric Oxide

Ultraviolet Radiation

Photochemical Smog

Ozone Layer thinning• Affect on seasonal changes

• Causes – chlorofluorocarbons (CFCs) that uses in:

• Coolants in air conditioners and refrigerators

• Propellants in aerosol cans

• Cleaning solutions for electronic parts

• Fumigants

• Bubbles in plastic packing foam

Ultraviolet rays from Sun

The Ozone layer in stratosphere blocks these harmful UV rays

Chlorofluorocarbons are entering in to atmosphere releasing chlorine. The chlorine than break down the ozone

The chlorine released from CFCs break down the ozone molecule.

chlorine

ozone

More ultraviolet radiations are reaching in to earths surface as there is a whole in ozone layer.

Oxygen

Whole in Ozone layer

Reversing Ozone Depletion• Stop producing ozone-depleting chemicals

• Slow recovery

• Montreal Protocol

• Copenhagen Protocol

• International cooperation

Indoor air qualityIndoor air quality (IAQ) is a term referring to

the air quality within and around buildings and structures.

IAQ can be affected by microbial contaminants (mold, bacteria), gases (including carbon monoxide, radon, volatile organic compound and particulates) .

Major Indoor Air Pollutants• Tobacco smoke

• Formaldehyde

• Radioactive radon-222 gas

• Very small particles

• Sick-building syndrome (SBS)

• Developing countries – Indoor cooking and heating

Air Pollution and the Human Respiratory System

• Natural protective system

• Lung cancer, chronic bronchitis, emphysema, asthma

• Premature deaths

Air Pollutants and its impact on human health

Particulate MatterDust and smoke particles cause irritation of the respiratory tract and produce bronchitis, asthma and lung diseases.

Dust and smoke function as nuclei for condensation of water vapors and produce smog which attract chemicals like SO2, H2S, NO2,etc. Smog not only reduce visibility but is also harmful due to its contained chemicals.

NOISE POLLUTIONThe term noise is applied to the sound that cause irritation on hearing of healthy human being.

Sources Transport noise--- Originates from road traffic (vehicular), air craft and rail traffic.

Industrial noise--- It produced by presses; punch and stamp machine, pneumatic drills, milling machines, cutter and routers, dust extractors. etc.

Domestic noise--- It is generated from domestic appliance like washing machines, spin dryers, food mixer, sink waste grinder and vacuum cleaner.

Effects Of Noise PollutionHearing damage from noise exposure

Pathological and Physiological disorders

The impact of noise may cause permanent

hearing loss due to the exposure to noise

levels exceeding 90 dB

What is sick building syndrome ?

The feeling of illness among majority of occupants of a conditioned space is called “Sick Building Syndrome”.

A variety of illness symptoms reported by occupants in sick buildings are – Headache, fatigue, irritation in eyes, nose and throat, shortness of breathe etc.

Causes:

Inadequate ventilation , insufficient

supply of outside air; poor mixing; fluctuations in temperature & humidity;

What is sick building syndrome ?

Health Effects of Indoor Air Pollutants

Health effects due to indoor air pollutants may be short- as well as long-term.

Short-term problems include a stuffy, odorous environment and symptoms such

as burning eyes, skin irritation, and headaches.

Long-term health problems have a longer latency period or are chronic in nature.

Health conditions involving some allergic reactions, including hypersensitivity pneumonitis, allergic rhinitis, and some types of asthma, are triggered by bioaerosols

Examples include banning smoking in public buildings.

Source-isolation strategy is used in situations where a source cannot be completely eliminated. For instance, copy machine areas, food service stations, and bathrooms are often separately vented outside buildings to avoid the recirculation of return air.

Control of Indoor Air Pollution

Questions

1-Sources of out door pollution are……………….2-Effects Of Noise Pollution are……………3-Two of Effects Of Noise Pollution are…………and………4- Source-isolation strategy is used in situations where a source…………..5- primary pollutants are substances directly emitted from a process, such as the ……………from a ............or ……..released from ……………..

6-What is sick building syndrome ? And it is effect on the health status of human being ?

7- What are the environmental challenges?

8-What are the classification of pollutants ?

Recommended text book

• Basic Environmental Health