There are many situations where human activities have significant effects on the environment. Ozone layer damage is one of them. The objective of this paper is to review the causes, control, mechanisms and effects of ozone layer depletion as well as the protective measures of this varnishing layer. Ozone layer is a layer in the earth’s atmosphere which contains relatively high concentration of ozone. Ozone layer depletion is caused by the presence of chlorine –containing source gases (primarily Cfcs and related halocarbons. This chlorofluorocarbons and halons are potent ozone depletors. The major effects of the stratospheric ozone depletion is an increase in the amount of ultraviolet beta radiations reaching the biosphere and this has potential impacts on the biosphere, human health and natural ecosystems, both aquatic and tersest rial and agriculture. Ozone layer depletion can be controlled by reduction in the emissions of CFCs (Chlorofluorocarbons and halons) which we use in our daily activities i.e man-made activities which is released into the atmosphere.

TABLE OF CONTENTS

Title page - - - - - - - i

Abstract - - - - - - - - ii

Table of contents - - - - - - iii

CHAPTER ONE

1.0 Introduction - - - - - - 1

1.1 formation of Ozone - - - -

1.2 Ozone layer cycle overview - - -

CHAPTER TWO

2.0 Causes of ozone layer depletion - -

2.1 Uses of ozone depleting substances (ODS) - - - - - - - - - - -

CHAPTER THREE

3.0 Effects of ozone layer depletion - - -

3.1 Effects on Human and animal health - -

3.2 Effects on terrestrial plants - - - -

3.3 Effects on Aquatic ecosystems - - -

3.4 Effects on Bio-Geo-chemical cycles - -

3.5 Effects on Air Quality - - - - -

3.6 Effects on materials - - - - -

3.7 Effects on climatic change - - - -

CHAPTER FOUR

4.0 Control of Ozone layer depletion - - -

4.1 Ways to prevent ozone depletion - - -

4.2 Conclusion - - - - - - -

References - - - - - - - -

CHAPTER ONE

1.0 INTRODUCTION

Ozone is a green house gas which absorbs the sun’s harmful ultraviolet light that can cause skin cancer; weaken the immune system, damage plants and marine creatures from entering the earth’s atmosphere. (Defabo et al., 1979, Yukio Takizawa 1990).

The ozone layer is a layer in earth’s atmosphere which contains relatively high concentrations of ozone. This layer absorbs 97-99% of the sun’s high frequency ultraviolet light, which is potentially damaging to life on earth. (Lubin et al., 1989, Fredrick et al 1988).

The ozone layer is threatened by a range of chemicals usually referred to as ozone depleting substances (ODS) which destroys the layer through a series of chemical reactions. These chemicals such as chlorofluorocarbons (CFCs), methyl – bromide etc. are released into the atmosphere owing to various activities caused by man such as the use of refrigerants (which release cfcs) and insecticides (Siedel and Daniel 1990).

Ozone layer depletion leads to thinning of the ozone layer thereby exposing the organisms on earth to harmful ultraviolet radiation and increase in global temperature with adverse effects on man, (Leading to skin cancer, eye disorders, immunological effects), aquatic life and land vegetation (Joe Buchdahl, 2002).

Ozone layer is also a deep layer in earth’s atmosphere that contain ozone which is a naturally occurring molecules containing three oxygen atoms. These ozone molecules form a gaseous layer in the earth’s upper atmosphere called stratosphere. This lower region of stratosphere containing relatively higher concentrations of ozone is called Ozonosphere. The ozonosphere is found 15-35km (9-22miles) above the surface of the earth. The average concentration of ozone in the atmosphere is around 0.6 parts per million. The thickness of the ozone layer differs as season and geography. The highest concentration of ozone occurs at altitudes from 26-28km (16-17miles) in the tropics and from 12-20km (7-12miles) towards the poles (Britannica 1992).

The ozone layer forms a thick layer in stratosphere, encircling the earth that has large amount of ozone in it. It protects our planet i.e earth from the harmful radiations that comes from the sun. The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henry Buisson. The ozone layer has the capacity to absorb almost 97-99% of the harmful ultraviolet radiations that sun emits and which can produce long term devastating effects on human beings as well as plants and animals (Coohill, T.P 1991).