The rate of destruction of the protective ozone layer in the upper reaches of the atmosphere is slowing. Scientists say it mirrors a decline in the use of certain man made chemicals. Using NASA Satellite observations, the scientists say the rate of the ozone layer depletion matches the drop in chloroflurocarbons used in refrigeration and air conditioning. The 1897 Montreal Protocols ratified by more than 170 countries requires that CFCs be phased our of production and use in developing countries by 2010. Industrialised nations stopped using them in 1996. Scientists said that it will take decades to repair the damage to the ozone layer, which helps protect the Earth from ultraviolet radiation from the sun. “Ozone is still decreasing but just not as fast”, said Mike Newchurch, associate professor at the University of Alabama and lead scientist on the study. “We are still decades away from the total ozone recovery” (Search Google for more info on this)
Ozone Day
On 19 December 1994, the United Nations General Assembly proclaimed 16 September the International Day for the Preservation of the Ozone Layer, commemorating the date, in 1987, on which the Montreal Protocol on Substances that Deplete the Ozone Layer was signed.
Ozone is very rare in our atmosphere, averaging about 3 molecules of ozone for every 10 million air molecules. In spite of this small amount, ozone plays vital roles in the atmosphere. Ozone is mainly found in two regions of the Earth’s atmosphere. Most ozone (about 90%) resides in a layer that begins between 8 to 18 kilometers above the Earth’s surface and extends up to about 50 kilometers, called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. If we collect all the ozone in the atmosphere, the ozone layer will be as thick as a one-rupee coin.
Ozone thus plays a key role in the temperature structure of the Earth’s atmosphere. Without the filtering action of the ozone layer, more of the Sun’s UV-B radiation would penetrate the atmosphere and would reach the Earth’s surface. The discovery of the ozone ‘hole’ in 1985 shocked the world. It is regarded as one of this century’s major environmental disasters. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation. It is estimated that, for every 2.5% depletion in ozone layer results around five-lakh skin cancer patient on earth.
Our country signed in the Montreal Protocol on 17.09.1992. India’s per capita consumption of Ozone Depleting Substances is at present less than 3 grams as against 300 gms permitted under the Protocol. Our country is taking strict measures to phase out the ozone depleting substances within the schedule period.
IN THE NEWS – IN GUJARAT
Science City Organize World Ozone Day Workshop – 16TH SEPTEMBER, OZONE DAY
To mark the celebrations for World Ozone Day, Gujarat Science City (GSC) has organized a day long Workshop with the theme ‘Protect the Ozone Layer : Save Life on Earth’ with initiatives for Ozone Layer protection: Governance and compliances at their best with exhibition, slide and film show and popular science talk on the ozone theme. The aim is to spread awareness and sensitize the students and the general visitors about the ozone layer and its importance to save life on earth. Participants from over 150 schools are expected to join the workshop on Thursday, 16th September 2010 – World Ozone Day. A sit and draw and Ozone Quiz competitions are held at the Science City where children of class VI to X will participate.
EARTH TALK Q & A BY EDITOR DOUG MOSS ON OZONE
Dear EarthTalk: I know of issues associated with the Earth’s ozone layer, but what is “ground level ozone” and why is that a problem?
Ozone (O3) is a colorless gas formed when three atoms of oxygen bond together. About 90 percent of the Earth’s ozone forms naturally in the stratosphere, dozens of miles above ground. It forms the protective layer that shields us from overexposure to the sun’s radiation, and is therefore considered “good” ozone.
The rest of the ozone found on Earth occurs at ground level, and forms when nitrous oxides and various “volatile organic compounds’ (VOCs)—originating with car exhaust, industrial emissions, chemicals and gasoline vapors, as well as some natural sources—bond together in the presence of sunlight.
Ground level ozone, or “bad” ozone, is a key component of smog, which wreaks havoc on human health and the environment, especially in urban areas. The U.S. Environmental Protection Agency (EPA) reports that exposure to even relatively low concentrations of ground-level ozone for extended periods (several hours) can significantly reduce lung function and cause respiratory inflammation in normal, healthy people. Symptoms can include chest pain, coughing, nausea and congestion. For people with asthma and other respiratory illnesses, exercising in ozone-rich air can be deadly. Repeated exposure to high levels of ozone for several months or more can produce permanent structural damage in the lungs.
Beyond its effects on our health, the EPA estimates that pollution from ground-level ozone is responsible for nearly $2 billion in agricultural crop yield losses in the U.S. alone each year. The pervasive gas has also been shown to damage forests in California and the eastern U.S. and to contribute to global warming.
Under the mandate of the Clean Air Act, the EPA is charged with monitoring and limiting the amount of ground-level ozone in urban areas, and issuing warnings when smog levels are above its standard of 0.12 parts per million. But new studies indicate that ground-level ozone causes adverse health effects at even lower concentrations. And, according to the EPA, even rural areas suffer increased ozone levels, because wind carries ozone and the pollutants that form it hundreds of miles away from their original sources. As a result, the EPA is reviewing whether revisions to ozone standards and policies are warranted.
High concentrations of ground-level ozone are not as common in Canada, but three urban regions—British Columbia’s Lower Fraser Valley, the Windsor-Québec City Corridor and the Southern Atlantic Region that includes New Brunswick and Nova Scotia—do suffer several “bad air days” each year. The Canadian government, through its own Clean Air Act, has even stricter standards for exposure to ground-level ozone than in the U.S., though enforcement is not as big a priority given the smaller scope of the problem there.
To help minimize ground-level ozone, avoid car trips and the use of power lawn equipment during especially hot or windless days. Paints and solvents, most which off-gas VOCs that create ozone and form smog, are also best to steer clear of with hot summer temperatures coming on strong. Those concerned about their respiratory health should follow local weather sources, most which post smog alerts.
CONTACTS: U.S. EPA Ground-Level Ozone Information, www.epa.gov/air/ozonepollution; Canada’s Clean Air Act, www.ec.gc.ca/cleanair-airpur/Home-WS8C3F7D55-1_En.htm.
