The United Nations first declared International Ozone Day on September 16th in 1995 in its resolution 49/114, in commemoration of the date on which countries signed the Montreal Protocol on substances that deplete the Ozone Layer in 1987. The commemoration around the world offers an opportunity to focus attention and action at the global, regional and national levels on the protection of the ozone layer. Every year the international ozone day is celebrated on various themes like “Save our Sky – There is a whole lot more to do.” The theme for this year is “Universal participation: Ozone protection unifies the world”.
What is Ozone?
Ozone is a colorless, odourless and highly reactive gas made of oxygen with three oxygen atoms joined together with the chemical designation O3.
Ozone is found in the Earth’s atmosphere in the lower portion of the stratosphere from approximately 10 km to 50 km above Earth in a layer called the ozone layer. This layer absorbs 93-99% of the sun’s high frequency ultraviolet light, which is potentially damaging to life on earth.
Ozone is also found in the troposphere and is known as ground/ low level ozone and is regarded as an air pollutant. It is formed in the atmosphere by photochemical reactions in the presence of sunlight and precursor pollutants, such as oxides of nitrogen (NOx) and volatile organic compounds (VOCs). It is destroyed by the reactions with NO2 and is deposited to the ground
Ozone found in the stratosphere is essential for human life as it is able to absorb much harmful ultraviolet radiation, preventing penetration to the earth’s surface. The ozone layer present in the upper troposphere protects life on earth and acts as a greenhouse gas by absorbing some of the infrared energy emitted by the earth preventing the harmful ultra-violet (UV) rays from reaching the earth’s surface. Because of these, ozone layer is also called as “protective shield”.
However at the earth’s surface, ozone is harmful to crops, forests, building materials and the health of humans and animals. Warm, sunny days with little wind and no rainfall help to form ozone, and unhealthy levels can occur, especially in cities. Ozone can be blown long distances from highly populated areas. Ozone levels are usually higher in the afternoon and early evening after traffic and industry have released large amounts of ozone-forming materials into the air.
The ground level ozone in the lower atmosphere (troposphere) should not be confused with the natural protective layer of ozone in the upper atmosphere (stratosphere). Although both are made of the same chemical, the ozone in the upper atmosphere protects us from the sun’s harmful ultraviolet rays, while the ozone in the lower atmosphere harms us.
Sources of Ozone
There are 3 main contributors to the ozone problem: human activity, natural sources, and volcanic eruptions.
Human activity is by far the most prevalent and destructive source of ozone depletion, while threatening volcanic eruptions are less common. Human activity, such as the release of various compounds containing chlorine or bromine, accounts for approximately 75 to 85 percent of ozone damage. The Chlorofluorocarbon present in the atmosphere is due almost entirely to human manufacture and the use of Chlorofluorocarbon gases (CFC’s) is posing the most evident threat to the existence of ozone in the stratosphere. CFC’s have a wide range because of its various properties like non- corrosiveness, non-inflammability, low toxicity etc. They are used as refrigerants, propellants in aerosol spray, foaming agents and in the cleaning processes of delicate electronic equipment. As CFC gases deplete the ozone layer because of release of chlorine in the atmosphere, many major countries have banned the use of CFC. Measures have been taken to reduce the amount of CFC emission, but since CFCs have a life span of 20-100 years, previously emitted CFCs will do damage for years to come. The rate at which ozone is being destroyed is much faster than the rate at which it is being formed.
Nuclear tests and emissions produced by supersonic jet aeroplanes also deplete the ozone layer. Burning of fossil fuels also releases carbon dioxide into the air, thickening greenhouse gases and thus adds to the greenhouse effect and global warming. It should be noted that greenhouse gas emissions, such as carbon dioxide and others, are not entirely destructive or bad as Carbon dioxide is necessary for life on earth.
Natural sources also contribute to the depletion of the ozone layer, but not nearly as much as human activity. Natural sources can be blamed for approximately 15 to 20 percent of ozone damage. A common natural source of ozone damage is naturally occurring chlorine. Naturally occurring chlorine, like the chlorine released from the reaction between a CFC molecule and UV radiation, also has detrimental effects and poses danger to the earth.
Finally, volcanic eruptions are a small contributor to ozone damage, accounting for one to five percent. During large volcanic eruptions, chlorine, as a component of hydrochloric acid (HCl), is released directly into the stratosphere, along with sulphur dioxide. In this case, sulphur dioxide is more harmful than chlorine because it is converted into sulphuric acid aerosols. These aerosols accelerate damaging chemical reactions, which cause chlorine to destroy ozone.
Effects: Ozone reacts chemically with internal body tissues casing inflammation. Breathing ozone may lead to serious health consequences, including premature death, shortness of breath and chest pains, wheezing and coughing, inflammation of the lining of lungs, increased susceptibility to respiratory infections, increased risk of asthma attacks, and increased need for medical treatment and hospitalization for people with lung diseases, such as asthma or chronic obstructive pulmonary disease.
Traces of ozone in the air do not harm but concentration greater than 0.1ppm is toxic and harmful to human beings. Depletion of ozone layer poses serious threats to human beings. According to the medical scientist, a larger exposure to U.V radiations due to decrease in ozone concentration leads to 2% increases in risk to skin cancer. U.V radiation also tends to damage the immune system which may lead to increased viral infections. It not only affects people with existing breathing problems, but also can affect healthy children and adults. Persons especially sensitive to ozone exposure are the elderly, infants, children, persons with existing respiratory issues such as asthma or allergies, asthmatics, chronic respiratory patients, pregnant women, smokers, and persons with lung cancer, cardiovascular disease or immune system deficiency. Symptoms include: irritation of the eyes, nose and sinuses; shortness of breath; chest pain; and wheezing or coughing. Other less common symptoms include: blurred vision, headache, nausea, vomiting, and fatigue. Excessive exposure to U.V radiations also damages vegetation, aquatic animals and plants.
To help with these issues, many have taken up green initiatives and encourage others to “go green.” Even some governments and environmental groups have targeted Carbon emissions that need improvement. Today many eco-friendly or green products are available on the market, especially in the automobile and energy industries to reduce the level of carbon emissions. A green business, for example, may install light tubes, geothermal climate control and take other measures to cut down on the use of fossil fuels for energy and everyday conveniences.
Ozone is always present at very low levels, but you can do certain things to reduce ozone
To reduce indoor sources of ozone:
• Avoid air cleaners that generate ozone. These devices can be effective in reducing smoke, odors and other air contaminants, but can cause adverse health effects by producing excess ozone.
• Ensure proper ventilation for rooms with ozone sources such as photocopiers.
• Maintain electrostatic air filters regularly.
To limit your exposure to outdoor ozone:
• Avoid exercising outdoors on days when ozone levels are at their highest.
• Stay indoors as much as possible on “ozone alert” days.
• Keep your motor vehicle properly tuned and drive no more than necessary on hot days.
“Ozone is a powerful greenhouse gas. Reducing ozone can help reduce Global Warming and Climate Change”
Issued in public interest:
BIOREMEDY
