The heatwave stifling France has caused a pollution spell that is 'both late and persistent' in the Île-de-France region around Paris, says Karine Léger, Director General of Paris Air quality monitoring organisation Airparif, adding that the episode is 'something relatively unprecedented in terms of ozone pollution.' Ozone is a noxious summer gas that needs heat and sunshine to form from other pollutants and 'is closely linked to global warming.' IMAGES AND SOUNDBITES