These devices, which work by combining hydrogen with oxygen from the air to produce electricity, are popular candidates to replace internal-combustion engines in road vehicles.

ECONOMIST: The dawn of micropower

At the cathode, the protons and the electrons react with oxygen from the air to make water which, to the joy of environmentalists, is the only waste product of such a cell.

ECONOMIST: The dawn of micropower

That's why it's called carbon dioxide, or C02 one carbon atom from the gasoline and two oxygen atoms from the air.

NPR: Has the Move to Make Cars Greener Stalled?

These nanoparticles then oxidise back into silicon oxides, drawing oxygen from the surrounding air.

ECONOMIST: Ball lightning

But in pressure-sensitive paints, excited luminescent molecules dump some of their energy into the oxygen in the air in a way that prevents them from lighting up.

ECONOMIST: Pressure paints | The

They provide safe havens for ocean wildlife to recover and maintain healthy biodiversity, supporting habitats that act as carbon sinks, removing CO2 from the air and generating the majority of atmospheric oxygen.

CNN: An SOS on World Oceans Day: Save our seas, save ourselves

To simulate the atmosphere, they have built a special cloud chamber of their own, with the air manufactured from scratch, using liquid nitrogen and oxygen together with precise amounts of trace compounds, including sulphuric acid and ammonia.

ECONOMIST: Climate science (II)

Medics are pumping down air from the surface with a 18 to 22 percent oxygen mix.

CNN: A day in the life of trapped Chile miners

To do that they need not one but two energy-hogging air chillers, one to make liquid oxygen and another to remove CO 2 from the flue gases.

FORBES: Entrepreneurs