Remember the Ozone Layer?
by Donna Thomson
Did you know it's been over 20 years since we first heard about the hole in the ozone layer? Thankfully in the 80's when it came to attention that manmade chemicals were destroying the layer, an international treaty (the 'Montreal Protocol' which is now ratified by over 180 nations) was created to ban those harmful chemical such as CFCs and bromides found in aerosol cans, refrigerants, fumigants and cleaning solvents. But what is the situation today and how will it impact our future?
Firstly, what is ozone?
The 'ozone layer' is found in the Earth's stratosphere where 90% of natural ozone gas is located. The other 10% of ozone is found in the troposphere which lies between Earth and the stratosphere. In its simplest form, NASA describes the purpose of the ozone layer as the earth's sunglasses, protecting us from the harmful effects of the sun's ultraviolet rays, specifically UV-B rays.
Effects of ozone depletion
An increase of UV-B rays due to ozone depletion affects people by causing cancer, cataracts and suppressing the immune system (1). Phytoplankton, the microscopic plants that live in the ocean, are adversely affected by UV-B rays which in turn affects the whole marine food chain. Plus, it's stated (2) that up to 25% of plant life could be affected due to the combination of an increase in UV-B rays and the greenhouse effect. Plastics, wood, paper, cotton and wool are also affected. Obviously this is detrimental to our health and the health of our planet.
Man-made ozone depletion
It can take 2 to 5 years for CFCs (chlorofluorocarbons) to reach the stratosphere because they are actually heavier than air. The UV radiation causes the CFCs to break apart once they reach the stratosphere, in turn releasing chlorine atoms which can each destroy more than 100,000 ozone molecules. Of course it isn't just CFCs which do the damage. Chemicals such as HCFCs (hydrochlorofluorocarbons), bromines and halons are just as harmful to the ozone layer. The only way to improve the situation is to stop production of those chemicals.
Natural ozone depletion
While large amounts of chlorine are also released via Earth's volcanoes and oceans, it is easily dissolved by rain within our atmosphere. In contrast, CFCs do not break down in water which allows them to travel up to the stratosphere and do their damage.
The 'ozone hole'
Ozone depletion occurs throughout the whole of our atmosphere but its levels aren't consistent due to the varying atmospheric conditions and altitudes across the planet. The 'ozone hole' refers to the very low ozone levels above the Antarctic (south pole). In the 1980s it was realised that due to the extreme cold of the Antarctic Winter and early Spring, plus the atmospheric pressures in that location, the ozone layer was more susceptible to ozone damage than other locations. The depletion of ozone in this location is concentrated and each Antarctic Winter/Spring since the early 80s, the 'ozone hole' has increased in size. The 'ozone hole' is about as big as the U.S. and at its deepest levels has a loss of around 66% ozone (3). Ozone levels are also depleted for similar reasons in the Arctic (north pole), however the 'ozone hole' does not occur there.
These low levels of ozone radiate into much of the Southern Hemisphere which is the reason for such an increase in UV-B related health problems like melanoma in Australians (4).
Can the ozone layer recover?
As of late May 2006, NASA claims that Earth's ozone layer is indeed on the road to recovery (5). While we can't make enough ozone to replace what's already been destroyed, if we stop producing ozone-depleting substances the natural ozone production reactions should return the ozone layer to normal levels by about 2050 (1), give or take twenty years either side of that. This is because the ozone layer has a natural balance between its depletion and production. It is the man-made production of ozone-depleting chemicals that has disrupted the natural balance and therefore it has to be via mans actions that the natural balance be allowed to resume.
The exciting news is that based on research (5), there has been significant improvement in the levels of CFCs in the Earth's upper stratosphere which directly corresponds to the banning of production of the harmful chemicals due to the Montreal Protocol. Even better news is that for some reason the ozone in the lower stratosphere is doing extremely well. It's suggested that changes in atmospheric wind patterns could have played a role in this 'bonus'.
Not out of the hot water yet
While some chemicals such as halons and HCFCs are still increasing in the atmosphere, it's predicted that they will fall in the next decades if the world continues to adhere to the Montreal Protocol. Paul Newman of NASA's Goddard Space Flight Center (6) predicts that around 2018 things should slowly start improving, and somewhere between 2020 and 2025 we'll be able to detect that the ozone hole is actually beginning to decrease in size. This is of course dependent on our consistent action towards keeping our planet free of ozone-depleting chemicals.
Much of the attention is on big business and their need to adopt ozone-friendly practices and product alternatives. However, there is much that can be done by the individual to ensure that our planet has a chance at recovery.
How can I be ozone-friendly?
Watch what you buy: Ensure products you purchase are labelled "CFC free" or "ozone friendly". Such products would be aerosol sprays, refrigerators, fire extinguishers, etc. These products should not contain ozone-depleting chemicals such as CFCs or halons.
Appliances: Dispose of old refrigerators and appliances responsibly. CFC and HCFC refrigerants should be removed from an appliance before it's discarded and refrigeration technicians should take special care to ensure the chemicals aren't released into the atmosphere during servicing or disposal. If your fridge or freezer is leaking gas, be sure to get this repaired as soon as possible.
Fire extinguishers: Portable halon-containing fire extinguishers should be returned to your fire protection authority for recycling. New fire extinguishers do not contain halon (e.g. dry powder).
On the farm: If you use methyl bromide for soil fumigation, switch to safer alternatives that are currently being used in many countries to replace this ozone-damaging pesticide. Also consider other options in pest control that do not rely on costly chemicals.
In the workplace: Ensure that items in your workplace are ozone-friendly. Items like water coolers, air conditioners, cleaning solvents, fire extinguishers and products such as aerosol sprays, foam cushions/mattresses and even paper correction fluid.
Overall, this is positive news 20 years on. The world seems committed to phasing out any existing ozone-depleting chemicals to restore the balance in Earth's stratosphere. The damage has been already been done though and there are enough ozone-depleting levels already in the stratosphere to continue to have an effect for a while yet. However, if we remain vigilant manufacturers and consumers it will only be a matter of time before the effects start to balance out as the experts predict. I picture this like a rubber band that will soon reach its maximum stretch and begin returning to normal. The efforts you take as an individual will help assist the earth to return to her natural balance.
References
(1) U.S. EPA. (2006). Brief Questions and Answers on Ozone Depletion. From:
http://www.epa.gov/ozone/science/unepSciQandA.pdf on 8 October 2006.
(2) Government of South Australia. (2006). Atmosphere - Ozone Depletion. From: http://www.environment.sa.gov.au/reporting/atmosphere/ozone.html on 8 October 2006.
(3) U.S. EPA. (2006). Myth: Ozone Depletion Occurs Only In Antarctica. From: http://www.epa.gov/ozone/science/glob_dep.html on 8 October 2006.
(4) Public Health Association of Australia. (1990). Policy: Stratospheric Ozone Depletion. From: http://www.phaa.net.au/policy/stratos.htm on 8 October 2006.
(5) Barry, P.L. and Dr. Phillips, T. (2006). Good News and A Puzzle, 05.26.2006. Science@NASA. From: http://science.nasa.gov/headlines/y2006/26may_ozone.htm on 8 October 2006.
(6) Myers, J. (2006). Ozone hole will disappear in 70 years: Research. Fri, 29 Sep 2006. Earth.org. From: http://www.earthtimes.org/articles/show/9067.html on 8 October 2006.