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The 'element of life' also makes the air that we breathe a perilous and costly atmosphere to operate in. Prof Andrea Sella of University College London provides presenter Justin Rowlatt with a characteristically striking argument for why oxygen is so 'incredibly dangerous'.

Pawanexh Kohli, in charge of India鈥檚 national cold chain strategy, explains why the oxygen needs of fresh vegetables and fresh meat are very different. Physics polymath Baldev Raj unpicks the mystery of Delhi鈥檚 1,600-year-old iron pillar, and explains just how damaging rust and corrosion can be. And, former 'smoke-jumper' Frankie Romero explains the mesmerising attraction of wildfires, and why stamping them out isn鈥檛 always a good idea.

(Photo: Wildfire in Los Alerces National Park, Argentina. Credit: AFP/Getty Images)