T

S

M

UV (A,B,C)

Vis, IR, dst

X

χ

Atmosfir Bumi

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What is Ozon ?

Ozone is a colorless gas that can be found in the air we breathe.

Each molecule of ozone is composed of three atoms of oxygen, one more than

the oxygen molecule we need to breathe to sustain life.

The additional oxygen atom makes ozone extremely reactive.

OZON : Good and Bad ?Ozone's unique chemical properties allow the ozone layer to act as our planet's sunscreen, providing an invisible filter to help protect all life forms from the sun's damaging UV rays.

Most incoming UV radiation is absorbed by ozone and prevented from reaching the Earth's surface.

Without the protective effect of ozone, life on Earth would not have evolved the way it has.

However, ozone is also found close to the Earth’s surface. This ground-level ozone is a harmful air pollutant

Good OZON

Ozone exists naturally in the Earth’s upper atmosphere, known as the stratosphere, where it shields the Earth from the sun’s ultraviolet rays. In the upper atmosphere, ozone occurs naturally and protets us from the sun’s ultraviolet radiation.

NATURAL Cycle Reaction in Stratosphir

O2 ------> O + O

O2 + O <-----

O3

UV-C1

O 3<----

- O 2+ O

UV-C

2UV-B

INTERCONVERSION PROCESS

How is stratospheric ozone formed?Ozone is created in the stratosphere when highly energetic solar rays strike molecules of oxygen (O2) and cause the two oxygen atoms to split apart. If a freed atom bumps into another O2, it joins up, forming ozone (O3).

Ozone is also naturally broken down in the stratosphere by sunlight and by a chemical reaction with various compounds containing nitrogen, hydrogen and chlorine. These chemicals all occur naturally in the atmosphere in very small amounts.

In an unpolluted atmosphere there is a dynamic balance between the amount of ozone being produced and the amount of ozone being destroyed. As a result, the total concentration of ozone in the stratosphere remains relatively constant. HOW OZON CONCENTRATION ?

Dobson Unit

Dobsin unit (DU) the principle unit for measuring ozone concentration. One DU is about twenty-seven million molecules per square centimeter ( the palm of your hand covers an area of rougly a hundred square centimeters). If 100 DU of ozone were brought to the Earth's surface, it would form a layer 1 millimeter thick. In the tropics, ozone levels are typically between 250 and 300 DU year-round.

Mengapa Khawatir ?• About 90% of all ozone occurs in the ozone layer, a

region of high concentrations approximately 15-40 kilometers (10-25 miles) above the Earth's surface, in the stratosphere.

• The ozone layer protects all life from ultraviolet radiation (UV) from the sun.

• Unfortunately, several chemicals used in air conditioning and certain industrial uses damage the ozone layer, allowing more UV to reach the Earth's surface.

• Since UV causes skin cancer, cataracts, and other harmful effects, ozone depletion will lead to increases in these problems.

• Increased UV can also lead to reduced crop yield and disruptions in the marine food chain.

Pengurangan Ozon

ODS ?

What is O D S ??

A compound that contributes to stratospheric ozone depletion. Ozone-depleting substances (ODS) include CFCs, HCFCs, halons, methyl bromide, carbon tetrachloride, and methyl chloroform. ODS are generally very stable in the troposphere and only degrade under intense ultraviolet light in the stratosphere. When they break down, they release chlorine or bromine atoms, which then deplete ozone.

Akibat Penipisan Ozon

What is ultraviolet radiation?Ultraviolet radiation is one form of radiant energy coming

from the sun. The various forms of energy, or radiation, are classified according to wavelength, measured in nanometres (one nm is a millionth of a millimetre). The shorter the wavelength, the more energetic the radiation. In order of decreasing energy, the principal forms of radiation are gamma rays, X rays, UV (ultraviolet radiation), visible light, infrared radiation, microwaves, and radio waves. There are three categories of UV radiation:

1. UV-A, between 320 and 400 nm 2. UV-B, between 280 and 320 nm 3. UV-C, between 200 and 280 nm

UV : A – B – C UV-C is characterized by wavelengths less than 280 nm. Although highly dangerous to plants and animals, this part of the UV spectrum is completely absorbed by stratospheric ozone and does not reachthe earth's surface.

UV-B ranges in wavelengths between 280 and 320 nm. Ozone absorbs much of the shorter wavelength radiation, but this absorption weakens as 320 nm is approached. Plants and animals are particularly affected by this part of the UV spectrum. UV-B effects to humans are reddening of the skin (erythema) and reduction of vitamin-D synthesis in the short term, development of skin cancer, cataracts and suppression of the immune system in the long term.

The wavelengths of UV-A radiation range between 320 and 400 nm. Ozone absorbs very little of this part of the UV spectrum. UV-A radiation is needed by humans for the synthesis of vitamin-D; however, too much UV-A causes photoaging (toughening of the skin), suppression of the immune system and, to a lesser degree, reddening of the skin, and cataract formation.

How harmful is UV?Generally, the shorter the wavelength, the more biologically damaging UV radiation can be if it reaches the Earth in sufficient quantity. UV-A, although it is the least energetic form of UV radiation, reaches the Earth in greatest quantity. Most UV-A rays pass right through the ozone layer.

UV-B radiation is potentially very harmful. Fortunately, most of the sun's UV-B radiation is absorbed by ozone in the stratosphere.

UV-C radiation is potentially the most damaging because it is very energetic. Fortunately, all UV-C is absorbed by oxygen and ozone in the stratosphere and never reaches the Earth's surface

OZON good and bad !

• The same ozone molecules that protect us from UV high in the stratosphere can cause health problems for people and animals when they form near the Earth's surface.

• Ground-level ozone is formed when vehicle exhaust and some other chemicals commonly used in industry mix in strong sunlight.

• When these ozone concentrations get high enough, they can make breathing difficult, especially for people with asthma and other respiratory diseases.

Why ground-level ozone is a harmful air pollutant ?

Even at relatively low levels, ozone may cause inflammation and irritation of the respiratory tract, particularly during physical activity. The resulting symptoms can include breathing difficulty, coughing, and throat irritation. Breathing ozone can affect lung function and worsen asthma attacks. Ozone can increase the susceptibility of the lungs to infections, allergens, and other air pollutants. Medical studies have shown that ozone damages lung tissue

How is ground-level ozone formed? (REACTION ?)

Bila tidak ada VOCs:O3 akan bereaksi dg. NO menghasilkan NO2 dan O2

TIDAK ADA AKUMULASI KARENA SIKLUS

Bila ada VOCs:O3 tidak berreaksi dg. NO karena ada VOC yang reaktif, dimana VOCs dengan NO membentuk PAN dan sejumlah senyawa CxHyOzN. Selain itu VOCs bisa bereaksi dengan O membentuk aldehid, keton. Sehingga di atmosfir ada oksidan fotokimia: O3, PAN, aldehid, dll

Polutan NO2 di atmosfir, akan mengalami reaksi foto kimia menjadi NO dan O

O akan bertemu dengan O2 menjadi O3

OZON (ground-level)

Ozone (O3) is an odorless, colorless gas composed of three oxygen atoms. It is not usually emitted directly into the air, but at ground level is created by a chemical reaction between oxides of nitrogen (NO) and volatile organic compounds (VOC) in the presence of heat and sunlight.

VOC + NOx + Heat + Sunlight = Ozone

A Q I for OZON

Picture in MS-word

How AQI found ?Ia - Ib

IKU = ------------ (Xx – Xb) + IbXa - Xb

IKU = Indeks Kualitas Udara Hasil PerhitunganIa = IKU batas atasIb = IKU Batas bawahXa = ambien batas atasXb = ambien batas bawahXx = Kandungan gas / pencemar di udara ambien

Tabel IndeksIndeks PM10

(24 jam)

SO2

(24 jam)

CO

(8 jam)

O3

(1 jam)

NO2

(1 jam)

50 50 80 5 120

100 150 365 10 235

200 350 800 17 400 1130

300 420 1600 34 800 2260

400 500 2100 46 1000 3000

500 600 2620 57,5 1200 3750

µg/m3 µg/m3 ppm µg/m3 µg/m3

Contoh Perhitungan

Hasil pengukuran O3 di udara = 270 ug/m3

Dari Tabel:Ia = 200Ib = 100Xa = 400Xb = 235

Masukkan ke dalam rumus, akan diperoleh:Indeks Kualitas Udara untuk O3 = 127,3 = 127

Kesimpulan:

Formation and destuction of ozoneSunlight is the major energy source for both making and destroying stratospheric ozone:

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