While the ozone layer in the upper atmosphere plays an important role in limiting harmful ultraviolet light reaching the Earth's surface, low-level ozone is a pollutant that is harmful, causing respiratory problems in animals as well as well-documented cases in humans.

BBC: Invasive plant 'increases ozone pollution'

At ground level ozone is a dangerous pollutant, but at altitude it blocks the passage of harmful ultraviolet light.

ECONOMIST: Atmospheric science: Fake flakes | The

It was also a big week for lighting news as we learned that compact fluorescent light bulbs emit potentially harmful UV radiation -- another good reason to make the switch to LEDs.

ENGADGET: Inhabitat's Week in Green: Eindhoven's Evoluon Center, folding compact cars and the best of 3D printing