Ozone

Ozone

by Quantum Supercomputing

​Intro

​Ozone (O3) is a triatomic molecule consisting of three oxygen atoms, which is generated by sunlight-driven reactions involving the oxides of nitrogen and volatile organic compounds.

​Ozone as a Pollutant

​In the lower troposphere, photochemical reactions of air pollutants (hydrocarbons and nitrogen oxides) produce ozone as well as other atmospheric oxidants such as hydrogen peroxide (H₂O₂), organic peroxides, and peroxyacyl nitrates that result in what is called photochemical smog. Ozone and other oxidants promote oxidation of sulfur dioxide (SO₂) and nitrogen oxides into sulfuric and nitric acids, respectively, bringing about the occurrence of acid rain. In addition, ozone has strong absorption bands in the infrared region near 9.6 μm, and hence is one of the so-called greenhouse gases. Monitoring of ozone concentration is thus indispensable for protection of both the local and global environment.

​

​Ozone health effects(Human)

​Ozone can aggravate asthma and increase susceptibility to respiratory diseases such as pneumonia and bronchitis. The TC_Lo is 50 ppm. Pulmonary symptoms at low levels (60–200 ppm) include substernal pain, cough, dry throat, wheezing, and dyspnea. The American Conference of Governmental Industrial Hygienists (ACGIH) lists ozone as A4 (not classifiable as a human carcinogen).

​Ozone health effects-Animal

​Ozone produces cell injury and connective tissue alterations in the lungs.

​The biochemical findings (e.g., increased lung content of DNA, protein, and collagen) were consistent with extensive breakdown and remodeling of the lung parenchyma and its associated vasculature. Histopathologic evaluation showed severe fibrosis, alveolar collapse, honeycombing, macrophage and mast cell accumulation, vascular smooth muscle hypertrophy, and other indications of severe progressive interstitial pulmonary fibrosis and end-stage lung disease. This animal model of progressive pulmonary fibrosis was judged to resemble the final stages of human idiopathic pulmonary fibrosis.

Multiple Choice

Good ozone is found in the

• a) troposphere

• b) stratosphere

• c) mesosphere

• d) both a and b

Multiple Choice

Photochemical smog is a

• a) primary pollutant

• b) secondary pollutant

• c) poisonous gas

• d) both b and c

Multiple Choice

Primary pollutants combine with ____________ to produce photochemical smog.

• sunlight

• O2

• O3

• CO

​Ozone layer

​Ozone plays important roles in atmospheric chemistry and physics. Up to 5×10¹² molecules cm⁻³ or 4–5 ppmv (10⁻⁶ mixing ratio by volume) of ozone is found in the stratosphere where the solar radiation intensity of shorter wavelengths is high. Ozone in the stratosphere has made it possible for animals to live on land by preventing harmful 200–300 nm UV radiation from reaching the Earth's surface.

​The absorption of UV radiation by ozone, however, heats the air, disturbing air convection and creating a layered structure in the stratosphere.

​Ozone Reactions

Ozone at the higher levels of the atmosphere is a product of UV radiation acting on oxygen (O2) molecules. The higher energy UV radiations split apart some molecular oxygen (O2) into free oxygen (O) atoms. These atoms then combine with the molecular oxygen to form ozone as shown-

O₂-UV→ O+O

O+O₂ → O₃ (Ozone)​

​Ozone layer depletion

​The gradual thinning of the earth’s ozone layer in the upper atmosphere due to the release of chemical compounds containing gaseous bromine or chlorine from industries or other human activities.

Ozone layer depletion is the deterioration of the upper atmosphere's ozone layer. This occurs when chlorine and bromine atoms in the atmosphere react with ozone, destroying the ozone molecules. One chlorine atom may destroy 100,000 ozone molecules, destroying faster than its formation.

The main causes of ozone depletion or formation of ozone hole are manufactured chemicals, especially halocarbon refrigerants, solvents, propellants, and foam-blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS). These compounds release chlorine and bromine on exposure to high ultraviolet light, which then contributes to ozone layer depletion.

​Causes of Depletion

Natural Causes

Certain natural factors, such as sunspots and stratospheric winds, have been discovered to degrade the ozone layer. However, it only accounts for 1-2 percent of ozone layer loss. Volcanic eruptions are also contributing to the ozone layer's depletion.

Chlorofluorocarbons

CFCs, or chlorofluorocarbons, are the primary cause of ozone layer loss. Solvents, spray aerosols, refrigerators, air conditioners, and other appliances emit these. The UV radiations break down chlorofluorocarbon molecules in the stratosphere, releasing chlorine atoms. These atoms react with and destroy ozone.

Nitrogenous Compounds

Nitrogenous Compounds are compounds that contain nitrogen. Nitrogenous chemicals such as NO2, NO, and N2O are major contributors to ozone depletion.​

​Causes contd.

​Rocket Launches

According to studies, unregulated rocket launches deplete the ozone layer far more than CFCs do. If not regulated, this might lead to a significant depletion of the ozone layer by the year 2050.

Ozone Layer Depletion Reaction

• When CFCs are discharged into the atmosphere, they interact with other Unregulated atmospheric gases and eventually reach the stratosphere. Strong UV radiations in the stratosphere degrade them, generating chlorine-free radicals.

CF₂Cl₂  → Cl + CF₂Cl 

• When chlorine is discharged, it can react with ozone (O3) to produce chlorine monoxide (ClO) and oxygen (O2).

Cl + O₃ = ClO + O₂

• When a molecule of chlorine monoxide (ClO) collides with another molecule of oxygen (O), it splits, releasing chlorine (Cl), which can “demolish” another molecule of ozone (O3), resulting in the catalytic cycle of chlorine.

ClO + O = Cl + O₂

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Ozone-Depleting Substances	Sources
Chlorofluorocarbons (CFCs)	Refrigerators, air-conditioners, solvents, dry-cleaning agents, etc.
Halons	Fire-extinguishers
Carbon tetrachloride	Fire extinguishers, solvents
Methyl chloroform	Adhesives, aerosols
Hydrofluorocarbons	Solvent cleaning, fire extinguishers, solvent cleaning

​Effects of Ozone Depletion

Effects on Human Health

Because of the ozone layer depletion, humanity will be directly exposed to the sun's dangerous UV radiations. This might lead to major health problems in people, such as skin illnesses, cancer, sunburns, cataracts, premature aging, and a weakened immune system.

Effects on the Environment

Plants may experience reduced growth, blooming, and photosynthesis as a result of strong UV light. The woodlands must also withstand the negative impacts of UV light.

Effects on Marine Life

Exposure to damaging UV radiation has a significant impact on planktons. These are at the top of the aquatic food chain. If the planktons are eliminated, the species in the lower food chain suffer as well.

Effects on Animals

Animals acquire skin and eye cancer as a result of direct exposure to UV radiation.​

Multiple Choice

The thinning of the ozone layer is also known as the

• ozone hole

• ozone gap

• ozone space

• ozone void

Multiple Choice

Ozone is formed in the

• troposhere

• stratosphere

• mesosphere

• thermosphere

Multiple Choice

SUnburn occurs when your skin is exposed to harmful ______ rays

• radio

• magnetic

• ultraviolet

• infrared

Multiple Select

CFCs are responsible for the damage caused to the ozone layer. Select ALL of chemical elements make up CFCs.

• Carbon

• Hydrogen

• Oxygen

• Fluorine

• Chlorine

Multiple Choice

What are "holes" in the ozone layer?

• places where the ozone concentrations are lower than under normal conditions, allowing more UV radiation to reach the Earth's surface.

• places where the ozone concentrations are higher than under normal conditions, allowing more UV radiation to reach the Earth's surface.

• places where the ozone concentrations are higher than under normal conditions, allowing lessUV radiation to reach the Earth's surface.

Multiple Choice

Where is the 'hole' in the ozone layer located?

• Over the United States

• Over Europe

• Over Antarctica

• Around the equator

Multiple Choice

Where is the "GOOD" ozone located?

• troposphere

• stratosphere

• mesosphere

• thermosphere

Multiple Choice

The Montreal Protocol banned the use of CFCs. What do they hope this will do for the ozone layer?

• Deplete it completely

• Make the ozone hole smaller

• Make the ozone hole larger

• Thin the layer to allow more gas to escape

Multiple Choice

Which of these sets of three items produce CFCs

• cars, factories, and cardboard

• spray cans, cardboard, insulation

• spray cans, refrigerant, cardboard

• spray cans, refrigerant, insulation

Multiple Select

Which are effects of UV radiation on living organisms? select ALL that are true.

• It can denature proteins in the eye and cause foggy vision or blindness.

• It can cause mutation in DNA.

• It can disrupt food chains by causing harm to photosynthetic organisms.

• It can stimulate the production of vitamin D.

Multiple Choice

How many ozone atoms can a single chlorine atom break down?

• 5,000
• 10,000
• 50,000
• 100,000

​Industrial uses of Ozone

​Ozone is being used in the field of water treatment, disinfection, decolorization, deodorization, organic synthesis, materials testing, dry etching and cleaning processes in semiconductor industries, and other industrial areas. The advantages of using ozone over other chemicals are: its strong oxidizing power, its clean nature leaving only oxygen after the treatment, and electrical generation at the site. Monitoring of ozone dose and residual levels is necessary in all these processes.

​Generation of Ozone(Artificially)

​Most big-time users of ozone, like drinking water treatment systems, install generators on the spot and make it as needed.   Several manufacturers make these generators.  Almost all of them work on the principle of injecting oxygen, either in the form of air or pure oxygen, and subjecting it to a high voltage electric discharge.  The spark produces ultra-violet light which breaks apart an oxygen molecule, O₂ , into two O ions.   These in turn react with another oxygen molecule to make ozone  O₃ .

Multiple Choice

Which is the proper expression about OZONE?

• Good Up High, Bad Nearby

• Bad Up High , Good Nearby

Multiple Choice

Which of the following is NOT an ingredient that is needed to produce the ozone hole?

• Infrared Light

• Cold Temperatures

• UV Light

• Chlorine from CFCs

​THE END