Royal Free Doctor on BBC 2

A Royal Free doctor has devised an experiment which saw a man locked inside an airtight chamber for 48 hours with just plants for company. Critical care consultant Dr Daniel Martin hoped that through photosynthesis, the plants would provide enough oxygen to keep the man alive.

The aim of the challenge was to demonstrate how important plants are to the eco-system, as people would not be able to function without them. Before the experiment, oxygen levels in the container were reduced to around 12%, just over half that in the air around us.

 Professor Iain Stewart, professor of geoscience at Plymouth University, then agreed to be locked in the chamber for two days. Among the plants, he was given a hammock to sleep in, a chemical toilet and a laptop computer. The container was around eight metres long and 2.5 metres high.

Throughout the experiment, Dr Martin monitored the health of both Prof Stewart and the plants. If carbon dioxide levels fell too low and the plants could not photosynthesise, Prof Stewart had to exercise to increase the amount of CO2 in the chamber, which the plants need to produce oxygen. But if the carbon dioxide levels were too high, it would be damaging to Prof Stewart and the plants.

At the end of the 48-hour period, oxygen levels were returned to almost the level found in the air around us.

The experiment, carried out at the Eden Project in Cornwall, was filmed for a BBC2 series entitled How To Grow a Planet. The first episode, which features the experiment, will be screened tomorrow night (7th Fenruary) at 9pm.