Importance of meteorology

1. Ozone Chemistry
Name: Priti Sharma
M.Sc. (Environmental science) 1st Semester
Indira Gandhi Centre for Human Ecology, Environmental
and Population Studies
University of Rajasthan

2. Contents
1. Introduction to Ozone Chemistry
2. Ozone layer
3. Formation of Ozone
4. Ozone Depletion
5. Ozone Depletion effect- Ozone hole
6. Ozone & air pollution
7. Ozone reactions
8. Health and Environmental Effects of Ozone
9. Ozone Chemistry in the Troposphere
10. Ozone Chemistry in the Stratosphere
11. Mitigation Strategies for Ozone Depletion

3. Introduction to Ozone Chemistry
Ozone chemistry plays a crucial role in
the Earth's atmosphere, impacting
both the stratosphere and troposphere.
This presentation provides an
overview of ozone chemistry, including
its formation, properties, and its
importance in atmospheric processes.

4. Ozone layer
The ozone layer is a protective layer of
ozone gas in the Earth's stratosphere, which
shields the planet from harmful ultraviolet
(UV) radiation. This slide discusses the
structure and importance of the ozone
layer, and the consequences of its depletion.

5. Formation of Ozone
Ozone in the stratosphere is primarily formed
through the photodissociation of molecular oxygen
(O2) by solar UV radiation. This process produces
oxygen atoms, which can then react with other
oxygen molecules to form ozone.
1 Stratospheric Ozone Formation
Tropospheric ozone is mainly formed through
photochemical reactions involving nitrogen oxides
(NOx) and volatile organic compounds (VOCs)
emitted from human activities and natural sources.
2 Tropospheric Ozone Formation
Apart from photodissociation reactions, ozone can
also be formed through lightning discharges, volcanic
emissions, and chemical processes in the presence of
pollutants.
Other Ozone Formation
Mechanisms
3
Various factors such as temperature, sunlight
intensity, atmospheric composition, and pollution
levels influence the formation of ozone in both the
stratosphere and troposphere.
Factors Affecting Ozone
Formation
4

7. Ozone Depletion
Causes of Ozone Depletion
The release of CFCs, a class of synthetic compounds used
in refrigeration, aerosol propellants, and foam-blowing
agents, has been a major cause of depletion in the ozone
layer. These chemicals release chlorine and bromine
atoms upon reaching the stratosphere, which catalytically
destroy ozone.
Chlorofluorocarbons (CFCs)
1
Halons, carbon tetrachloride, and other ozone-depleting
substances also contribute to ozone depletion through
similar catalytic processes.
Halons and Other Ozone-Depleting
Substances
2

8. Ozone Depletion effect
The Ozone Hole
The Antarctic ozone hole,
discovered in the 1980s, is a
region of severe ozone
depletion that occurs annually
during the Southern
Hemisphere's spring. It is
primarily attributed to the
presence of polar stratospheric
clouds and the high levels of
ozone-depleting substances in
the region.
Antarctic Ozone Hole
Ozone depletion leads to
increased levels of harmful UV
radiation reaching the Earth's
surface. This has adverse effects
on human health, including skin
cancer, cataracts, weakened
immune systems, and damage
to marine ecosystems and
agricultural productivity.
Effects of Ozone Depletion
The Montreal Protocol, an
international environmental
agreement, was established to
regulate the production and
phased out the use of
ozone-depleting substances.
This slide highlights the
achievements and challenges in
addressing the ozone hole
through global cooperation.
Global Efforts to Address
the Ozone Hole

9. Ozone & air pollution
Interactions and Effects
Ozone formation in the troposphere is closely linked
to air pollution. This section explores the interactions
between nitrogen oxides, volatile organic
compounds, sunlight, and temperature, which
contribute to the production of ozone and its adverse
effects on human health and the environment.
Tropospheric Ozone Formation
and Air Pollution
1
Ozone pollution episodes, commonly known as smog,
occur when high levels of ozone are present near the
Earth's surface. This slide discusses the causes,
impacts, and mitigation strategies for ozone pollution
events.
2 Ozone Pollution Episodes
Exposure to high levels of tropospheric ozone can
lead to respiratory problems, lung damage, and
increased susceptibility to respiratory infections. This
section examines the health risks associated with
ozone pollution, particularly for vulnerable
populations such as children, the elderly, and
individuals with pre-existing respiratory conditions.
Health Effects of Ozone
Pollution
3
Ozone pollution also affects plants, crops, and
ecosystems. It can damage vegetation, reduce crop
yields, and disrupt ecological balance. The slide
highlights the environmental consequences of ozone
pollution and the importance of controlling its
emissions.
Environmental Impacts of
Ozone Pollution
4

10. Ozone reactions
Chemical Processes
This section explores the complex
chemical reactions involved in the
stratospheric ozone cycle, including
the Chapman cycle, catalytic
destruction by halogens, and the role of
other trace gases. It emphasizes the
delicate balance between ozone
formation and depletion in the
stratosphere.
Tropospheric ozone undergoes
numerous chemical reactions, both
anthropogenic and natural. This slide
discusses reactions involving nitrogen
oxides, volatile organic compounds,
and other pollutants, which contribute
to the production and destruction of
tropospheric ozone.
Stratospheric Ozone Reaction
Cycle Tropospheric Ozone Reactions

11. Health and Environmental Effects of Ozone
Exposure to high levels of ozone poses
significant risks to human health and the
environment. This slide explores the various
health effects of ozone exposure, including
respiratory problems, lung diseases, and the
formation of smog. Additionally, it discusses
the environmental impacts of ozone, such as
damage to vegetation and ecosystems.

12. Ozone Chemistry in the Troposphere
Reactive Processes
Tropospheric Ozone Formation
1
This section examines the primary mechanisms of tropospheric ozone formation, such as photochemical
reactions involving nitrogen oxides and volatile organic compounds. It also discusses how meteorology,
topography, and emissions influence the distribution and concentration of tropospheric ozone.
2 Tropospheric Ozone Sinks
The removal of tropospheric ozone occurs through various sinks, including chemical reactions, dry deposition
onto surfaces, and wet deposition through rainfall. This slide explores the different processes that contribute to
the removal of tropospheric ozone from the atmosphere.
3 Air Quality and Ozone Regulations
To mitigate the impacts of tropospheric ozone on air quality, regulatory measures have been implemented
worldwide. This section highlights the importance of monitoring and controlling ozone levels to protect human
health and the environment.

13. Ozone Chemistry in the Stratosphere
Formation and Destruction
This section explains the formation of stratospheric
ozone through photodissociation reactions and the
role of the ozone-oxygen cycle. It also discusses the
influence of solar radiation, temperature, and other
factors affecting the distribution of ozone in the
stratosphere.
1 Stratospheric Ozone Formation
Stratospheric ozone depletion occurs as a result of
catalytic reactions involving chlorine and bromine
atoms. This slide explores the key processes, such as
the catalytic destruction by CFCs and halons, and
their impact on stratospheric ozone levels.
2 Stratospheric Ozone Depletion
The Antarctic ozone hole is an extreme example of
stratospheric ozone depletion, mainly caused by
polar stratospheric clouds and the presence of
ozone-depleting substances. This section examines
the formation and seasonal variation of the ozone
hole.
3 Antarctic Ozone Hole
The success of the Montreal Protocol and subsequent
amendments led to a gradual recovery of
stratospheric ozone. This slide outlines the positive
trends observed in stratospheric ozone levels and the
ongoing challenges in achieving a full recovery.
4 Stratospheric Ozone Recovery

14. Mitigation Strategies for Ozone Depletion
Global Efforts
The Montreal Protocol
1
The Montreal Protocol, adopted in 1987, is a global
agreement aimed at reducing the production and use of
ozone-depleting substances. This section discusses the
provisions of the protocol, its success in phasing out CFCs
and other ozone-depleting chemicals, and the challenges
in implementing and enforcing the agreement.
2 Technological Innovations
Advancements in technology have provided alternatives to
ozone-depleting substances in various sectors such as
refrigeration, air conditioning, and aerosol propellants.
This slide explores some of the innovative technologies
and solutions that contribute to mitigating ozone
depletion.

15. Thank You and Q&A