Cool and compressed

Although CFCs and related chemicals are being phased out because they damage
the ozone layer, it has been difficult to find a replacement for them in car air
conditioning. Daimler-Benz of Germany is now testing an air conditioner that
uses compressed carbon dioxide instead. The gas was used in early refrigerators,
but abandoned since it needs very high pressure. With modern materials, this is
no longer a problem, says Daimler-Benz.