A NASA Goddard Space Flight Center satellite has observed the lowest value of ozone ever seen in the Northern Hemisphere since satellites first began ozone measurements in 1978. The measurement was obtained on November 30, 1999 using the Total Ozone Mapping Spectrometer (TOMS) instrument aboard NASA's Earth Probe (TOMS-EP) satellite. The record from TOMS during its full operation is available here.
 

"This is an extremely low measurement of ozone for the Northern Hemisphere," said Dr. Richard McPeters, Principal Investigator for Earth Probe TOMS. The measurement showed 165 Dobson Units (DU) over the North Sea between Scotland and Norway.

Audio clip from a NASA presentation regarding the importance and implications of the ozone hole.

Quicktime movies for some recent years in the Antarctic.
1994 Quicktime Movie (800K)
Animated Gif for 1996
 

Below are some timeseries of ozone that show variations in various locations and time periods. (click on the images for a clearer view)
 

	The continually decreasing minima ozone levels from year to year.
	The increasing size of the ozone hole.
	The long-term decrease in ozone over Antarctica.
	The surprising decrease in ozone even at midlatitudes.