The Nairobi Validation Station, the first of its kind in tropical and sub-tropical Africa, has been installed within the grounds of the UN Environmental Programme (UNEP) at Gigiri. The agency, which is involved in the work, said the station would detect ozone, emitted from the East African part of the tropics and formed from sources such as industry, transport, agriculture forest fires and charcoal burning. When the station was inaugurated today, UNEP Executive Director Klaus Toepfer called ozone a “curious chemical,” noting that in the upper atmosphere, it acts as a shield, protecting life on Earth from damaging levels of solar radiation. “In the lower atmosphere, known as the troposphere, small amounts are helpful, acting as a detergent to clean the air,” he added. “But high amounts, formed by sunlight mixing with human-made pollution from cars, factories and other sources, can be harmful, Mr. Toepfer said. “These smogs – increasingly a phenomenon in developing as well as developed countries – can prove fatal for vulnerable people such as those with heart conditions and asthma, and can also damage car tires, electricity cables and crops.” One of the key roles of the new station is to help unravel the fate of ozone damaging chemicals produced in the region from both human-made and natural sources such as vegetation. Scientists are unsure as to how much of this pollution makes its way into the upper atmosphere and how much remains closer to the ground. Understanding this is crucial to knowing how quickly the ozone layer may recover after decades of destruction by substances such as chlorofluorocarbons (CFCs). Once in the upper atmosphere, ozone-damaging chemicals can travel north and south towards the poles where, in the colder conditions, the layer is at highest risk.
Rajen Mahendra, 26, from CambridgeCredit:LinkedIn His friends have described him as a “fun-loving, adventurous, kind hearted and caring person”Credit:Family handout Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. All three men were skiing the 45-degree couloir when Mr Cassagneau-Francis and Mr Mahendra lost control and plunged several hundred metres down the icy, rocky terrain, with hard, compacted snow. Friends of Dr Cassagneau-Francis have paid tribute to him. Mr Cassagneau-Francis and his friend Mr Mahendra, who were both born and brought up in Cambridge, were skiing in an area popular with off-piste skiers.But conditions are particularly unfavourable at the moment and mountain experts have warned skiers to exercise the utmost caution if considering venturing off-piste. A spokesman for the PGHM, the high mountain police in Chamonix, said: “Three British men were skiing Le Couloir Du Chapeau. It is a steep off-piste area. The snow at the moment is very hard, it is not powder skiing. The two men fell several hundred metres, within a couple of minutes of each other.“For sure these men were good skiers but the conditions are not good. An investigation has been opened into the accident.”Police refused to say whether the skiers were wearing helmets.As a teenager Mr Mahendra attended the fee paying Perse School in Cambridge, while Mr Cassagneau-Francis went to Netherhall School and then Hills Road Sixth Form College and the pair frequently socialised together.Mr Cassagneau-Francis went on to train as a junior doctor at Newcastle University and at Lewisham and Greenwich NHS Trust, in south east London, while Mr Mahendra joined the international advertising and PR group Reprise Media.Both Mr Mahendra and Mr Cassagneau-Francis were keen sportsman and the pair had skied together with their families during the past decade.A grinning selfie of Mr Mahendra and his friends was posted on Twitter by an old schoolmate, with the caption: “Perse 2010. Older, not wiser”. Another shows him making a speech to the table of young men, dressed in a novelty Christmas jumper. They said: “Oscar was a fun-loving, adventurous, kind hearted and caring person who touched the hearts of everyone he knew. He will be sorely missed but greatly remembered by all those that know and love him. The world is a darker place without his cheeky smile & zest for life.”A spokeswoman for the men’s tour operator Inghams said: “We are working closely with local authorities in Chamonix, France, and the British Consulate, following the fatal accident involving two skiers. Our thoughts are with the family and friends of our guests at this difficult time.”According to police, there was evidence that other skiers had skied the slope in previous days.The bodies of the two men were retrieved from the mountain by helicopter and police have opened an investigation into the tragedy. Officers are due to interview Oliver Cassagneau-Francis, who was not injured, but was yesterday described as being in shock. Mr Cassagneau-Francis’s brother Oliver Phillipe recently finished studying for a postgraduate degree in Economics at French university Sciences Po.Before this, he studied for a BSc in the subject in his hometown, at the University of Cambridge.Like his brother he is understood to have been a keen skier, often posting photographs of himself on the slopes.On one photograph of his brother Oliver Phillipe trekking up a mountain, apparently preparing to ski off-piste, Mr Cassagneau-Francis wrote: “New skis? And when can i come see you?!?! Skype me sometime”.Stuart Macdonald, a British IFMGA mountain guide based in Chamonix, said: “This is an extremely serious couloir to ski at any time because there is a cliff at the bottom that you need to exit beforehand and it is a 45-degree slope. This is extreme skiing in any conditions, let alone Sunday’s.”It is west-facing and relatively low in altitude and the past week we have had plenty of sun and no fresh snow. All these factors mean I would not have skied that couloir on Sunday.”They may have seen tracks in the snow that they then followed, but in Chamonix, in particular, you could well be following a world-class skier.” A British skier witnessed a tragic accident in which his younger brother and a close childhood friend fell to their death in the French Alps.Experienced skier Oscar Cassagneau-Francis and his friend Rajen Mahendra, both 26, plunged several hundred metres to their deaths in Chamonix-Mont-Blanc while skiing off-piste.Mr Cassagneau-Francis’ older brother Oliver Phillipe, 28, also a keen skier, saw one of the men fall at around 11.40am on Sunday.He managed to raise the alarm with the piste patrollers who then radioed the mountain police in a desperate bid to find the pair alive.It is not known if the second skier fell while Oliver Phillipe was calling for help but he told rescuers he did not see the second fatal fall.Mr Cassagneau-Francis had been on several skiing trips, but the weather conditions on the 1700 metre high Le Couloir Du Chapeau, a steep section of the famous Grands Montets ski area, were said to be perilous, despite the glorious sunshine.