…the invisible umbrella

The environmental calendar is full of special days when we are asked to remember or think about something important.  Next Thursday, September 16, is the International Day for the Preservation of the Ozone Layer.

Since 1995, Ozone Day has marked the anniversary of the Montreal Protocol on Substances that Deplete the Ozone Layer.  The Protocol, part of the United Nations Environment Program, committed most of the UN’s membership to phasing out production and use of ozone-depleting substances.

What is ozone, and why do we care?  Ozone is a colourless gas, a form of oxygen with three atoms to the molecule (instead of two in the stuff we breathe).  Most of it is found in a thin layer in the middle part of our atmosphere, about 15 miles up.  It’s not very stable.  The molecules that form the “ozone layer” are constantly being knocked apart and recreated by the action of sunlight.  (Electricity can also create ozone;  the sharp metallic tang you may smell during a violent thunderstorm is ozone produced by a nearby lightning bolt.)
The ozone layer is a shield that’s vital to preserving life on earth.  It absorbs a lot of the energy from ultra-violet radiation (UV) -- the hottest part of the sun’s light.  The hazards of too much UV exposure for people and animals include increased risk of skin cancer, eye cataracts and immune system damage.

The substances that threaten the ozone layer are compounds containing chlorine and bromine, including the chlorofluorocarbons (CFCs) used in aerosol sprays.  The pictures show how the damage happens.

There has been a lot of progress getting rid of these harmful substances.  UNEP’s latest published assessment shows consumption falling from 1.3 million tonnes in 1986 to 10,260 in 2008 (the last year for which global figures are available).  In fact, the UNEP announcement of this year’s Ozone Day hailed the Montreal Protocol as “a shining example of international cooperation” and noted that “there is every reason to believe that the 2010 phase-out goals have been achieved by most of the [developed countries]”.

By 2015 eight of the nine substances identified by the Montreal Protocol will no longer be produced or used, but it could take until 2040 to find safe, practical substitutes for the hydrochlorofluorocarbons (HCFCs) used in refrigeration, fire extinguishers and foam manufacturing.

Jamaica achieved all its Montreal Protocol targets ahead of schedule, and was the first Caribbean country to do so.  Together with Cuba, Jamaica is testing the use of an effective, energy-efficient hydrocarbon substitute for HCFCs in refrigeration.

We can all carry on the good work by looking for the “ozone-friendly” labels when we buy things like refrigerators, air conditioners, fire extinguishers and household sprays, and by making sure our old fridges and air conditioners have the coolant safely removed when we dispose of them.  Though the ozone layer has stopped thinning, it will still be very fragile for at least another ten years.  It needs all the protection we can give it, so it can go on protecting us.