Every Wednesday morning, experts at the Kenya Meteorological Department, Nairobi, gather for an important exercise.

At exactly 9.00am, an inflated balloon filled with hydrogen gas and fitted with two small gadgets is released into the air.

It ascends the skies at an average speed of four or five metres per second to a distance of up to 35km above sea level before it bursts.

While the balloon goes up, computer screens on the ground collect, analyse and store data on the state of the ozone layer in Kenya. This seemingly amusing exercise has been carried out routinely since 1996. 

The ozone layer is a region of the earth’s stratosphere (the second layer of the atmosphere as you go up), located 15-50km above the earth.

It absorbs most of the sun’s ultraviolet rays and limits radiation that reaches the ground.

“Ozone layer is of utmost importance in protecting human health because it shields us from the sun’s radiation that causes skin cancer, eye cataracts and lowers the immunity.

It also protects plants, single cell organisms and aquatic ecosystems from being damaged,” says Kennedy Thiong’o, senior assistant director, Climate Services,  Kenya Meteorological Department. 

Vital negotiations

Launching a balloon into the atmosphere, a process referred to as vertical profile measurement of the ozone, is a synchronised activity done globally in line with Vienna Convention, a multi-lateral environmental agreement.

Back in the 1970s, scientists raised concerns that the ozone layer was getting depleted.

Extensive research eventually revealed that the thinning of the layer was due to chemicals known as Chlorouflourocarbons (CFCs), which were causing damage to the stratosphere.

“CFCs waft into the stratosphere, where they are broken down by ultraviolet radiation and break down into chlorine and bromine atoms, which damage the ozone layer,” says Thiong’o.

Later in 1985, British scientists discovered a significant reduction of the ozone levels at the Antarctica, in what has come to be popularly referred to as the “ozone hole”.

Negotiations between countries led to the signing of Vienna Convention in 1985 to  reduce the production of CFC gases, previously used in refrigeration, air conditioners and in fire extinguishers, to protect the ozone.

Later in 1987, United Nations member states signed the Montreal Protocol that called for phasing out of substances contributing to ozone depletion.

Kenya, being a signatory to both international agreements, replaced ozone-depleting chemicals with safer alternatives such as the Hydroflourocarbons (HFCs) to replace CFCs in  refrigeration and air conditioning .

Significant success

Through implementation of both Vienna and Montreal conventions, there have been significant strides towards the recovery of the ozone layer.

As the world marked, International Day for the Preservation of the Ozone Layer yesterday, under the theme “32 years and Healing”, experts applauded the incredible international cooperation that had led to its sustained recovery.

Under the Montreal Protocol, 99 per cent of the ozone-depleting chemicals have been phased out. As a result, the ozone has recovered at a rate of one to three per cent per decade since 2000, according to a scientific assessment by United Nations.

Locally, these conventions have equally had significant success. Besides, using the balloon to assess the state of the layer, Kenya has been measuring the column amount of the Ozone since 1984.

Results show the country has healthy ozone. “Kenya’s ozone averages at 251 Dobsom units.

Any measurement below 200 Dobsom units means the ozone is depleted,” adds Thiong’o. Kenya’s maximum Ozone layer is at 27km above station level.

Despite the success brought about by phasing out of CFCs, there are concerns that their replacements, HFCs, are contributing to global warming.

To avert their harmful effects, nations made an amendment to Montreal Protocol in Kigali in 2016.

The amendment, which came into force in January this year, proposes phasing down of the use of HFCs to prevent global temperatures from rising.

Besides, the actions taken by countries to protect the ozone layer and reduce global warming, there are personal steps one can take to aid in the same.

One such example is use of natural air conditioning methods as opposed to relying on equipment containing HFCs.