Diageo-owned Johnnie Walker has unveiled six limited edition bottles for its Black Label series, created using an ink made from air pollution.The Keep Walking City collection was made in partnership with Air-Ink, a brand that creates ink by condensing carbon-based gaseous effluents generated by air pollution. Six cities are represented by individual bottles in the range, and only 2,500 bottles per city will be available to purchase between July to September this year. The cities comprise: Mexico City, New Delhi, Warsaw, Bangkok, Istanbul and Madrid. Johnnie Walker global brand director Julie Bramham said: “Johnnie Walker is built on a legacy of making positive, progressive choices and to bring this collection to life we asked artists to shine a light on what makes their city special and inspires people to come together to 'keep walking'. "We are really thrilled by the unique depictions that have come out of this brief and combined with the Air-Ink partnership it demonstrates the power of combining art and innovation, making this limited edition range a true collectible.” The Black Label Blended Scotch Whisky includes flavours of toffee, fruit and spicy vanilla, and is bottled at 40% ABV. Nikhil Kaushik, co-founder and CEO of Graviky Labs, added: “Like Johnnie Walker, innovation, craft and creativity are rooted in our DNA and partnering with the brand for this limited edition series is so exciting. This marquee collaboration will set new standards in re-imagining how products of tomorrow can be made by utilising environmental carbon.” The six artists featured as part of the limited edition series include: Alek Morawski, the artist who designed the Warsaw bottling; Okuda San Miguel, for Madrid; Paola Delfín, for Mexico City; Shilo Shiv Suleman, for Delhi; Mr Hure for Istanbul; and Gongkan, for Bangkok. Morawski said: “It has been a pleasure to be part of this project and share a vision of my city, something that is very close to my heart. I think that turning air pollution into ink is a great idea – not only by minimising our carbon footprint, but also by broadening the conversation about what can be done about our future. I hope my work can inspire others to take new steps in bettering our city.” Earlier this year, the brand launched its Johnnie Walker Black Label Sherry Finish as a limited edition whisky.