Veuling Airbus A320-200. Registration: EC-HQJ Geneva/Barcelona Flight No: VY6204 The French BEA reported the occurrence was rated a serious incident and is being investigated. The crew felt strongly ‘inconvenienced’ after climbing through FL100 out of Geneva, donned their oxygen masks, subsequently declared an emergency and diverted to Marseille. Allegedly ‘Passengers and cabin crew were not inconvenienced’. . Passengers may have felt it was an inconvenience going to Marseille rather than their preferred destination of Barcelona. . Passengers and crew may not have presented any signs of ‘inconvenience’ at the time as these ‘inconveniences’ (health issues) may present a day or two later. If passengers are not informed of these events by airlines when they occur any link to their ill health will never be established.