Ozone & You

All about ozone and
the ozone layer

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single-atom
This is a

Single
Oxygen
Atom

single-atom
single-atom
And this is

Oxygen
O₂

Together they make a

Triple Oxygen
Molecule

Also known as

Ozone
O₃

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single-atom
O₃ Makes up the

Ozone
Layer

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earth
full-rays
The ozone layer

Deflects
harmful
radiation

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sun-rays
without the ozone layer

There are
serious
consequences

without the ozone layer

There are
serious
consequences

The Problem

So, what causes the thinning of the ozone layer around the globe and the “ozone hole” above Antarctica?

Manmade chemicals containing halogens were determined to be the main cause of ozone loss. These chemicals are collectively known as ozone-depleting substances (ODSs). The most important are chlorofluorocarbons (CFCs), which at one time were widely used in air conditioners, refrigerators and aerosol cans. Other chemicals, such as hydrochlorofluorocarbons (HCFCs), halons and methyl bromide also deplete the ozone layer.

Most of our computers, electronics and parts of our appliances were cleaned with ozone-depleting solvents. Car dash boards, insulation foams in our houses and office buildings, water boilers and even shoe soles were made using CFCs or HCFCs. Offices, computer facilities, military bases, airplanes and ships extensively used halons for fire protection. All kinds of sprays such as hair sprays and inhalers used by asthma patients were propelled by CFCs. A lot of the vegetables we ate were fumigated by methyl bromide to kill pests. ODSs were used in literally thousands of products.

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THE PROBLEM

Ozone depletion and
the “ozone hole”

In the mid-1970s, scientists became aware that the ozone layer was threatened by the accumulation of gases containing halogens (chlorine and bromine) in the atmosphere. Then, in the mid-1980s, scientists discovered a ‘hole’ in the ozone layer above Antarctica – the region of Earth’s atmosphere with severe depletion.

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The Problem

How do these chemicals deplete ozone?

When a CFC molecule reaches the stratosphere, it eventually absorbs UV radiation, causing it to decompose and release its chlorine atoms. One chlorine atom can destroy up to 100,000 ozone molecules. Too many of these chlorine and bromine reactions disrupt the delicate chemical balance that maintains the ozone layer, causing ozone to be destroyed faster than it is created.

The Consequences

Without the Montreal Protocol, large-scale depletion of the ozone layer would have occurred with major consequences

Because of the Montreal Protocol we have avoided a world where ozone depletion would have led to massive increases of UV radiation. Severe ozone holes would have occurred every year over the Arctic and the Antarctic. By the mid-21st century, severe ozone depletion would have spread across the planet including the tropics. This global ozone depletion would have increased UV-B to levels above anything experienced on Earth with severe consequences worldwide. Let’s explore some of those consequences.

The Solution

The Solution

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The Solution

In the 1980s, the global community decided to do something about ozone depletion. With growing evidence that CFCs were damaging the ozone layer and understanding of the many consequences of uncontrolled depletion, scientists and policy makers urged nations to control their use of CFCs. In response, the Vienna Convention for the Protection of the Ozone Layer was adopted in 1985, followed by the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987. They are the first international environmental treaties to be universally endorsed by 197 nations of the world.
The

Vienna Convention

The Vienna Convention for the Protection of the Ozone Layer was adopted in 1985 and entered into force in 1988. Nations that signed the Convention – called the parties – agreed to research and monitor the effects of human activities on the ozone layer...
and to take concrete action against activities that are likely to have adverse effects on the ozone layer.

The Convention did not require countries to take specific actions to control ozone-depleting substances. The specific actions are spelled out by the Montreal Protocol.

the

Montreal Protocol

The Montreal Protocol on Substances that Deplete the Ozone Layer is a global agreement to protect Earth’s ozone layer by phasing out the consumption and the production of most chemicals that deplete it. The landmark agreement was signed on 16 September 1987 – marked globally as the World Ozone Day - and entered into force in 1989. The Protocol provides a set of practical, actionable tasks to phase out ozone-depleting substances that were universally agreed upon.

The Protocol is unique in having the flexibility to respond to new scientific information. Since its inception the Protocol has successfully met its objectives, and continues to safeguard the ozone layer today.

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the

Kigali Amendment

Although the Montreal Protocol was designed to phase out the production and consumption of ODSs, some replacements of these substances, known as hydrofluorocarbons (HFCs), have proven to be powerful greenhouse gases. In fact, some HFCs are more than a thousand times more potent than carbon dioxide in contributing to climate change.

After several years of effort, the parties agreed on 15 October 2016 to amend the Protocol to include control measures to reduce HFCs (the Kigali Amendment). A successful HFC phasedown is expected to avoid up to 0.5 degree Celsius of global temperature rise by 2100, while continuing to protect the ozone layer.