Ozone levels show dip in far north, researchers say

WASHINGTON – Ozone levels over the Earth’s far north dipped sharply early last year when polar winds trapped nitrogen pollutants, researchers reported Tuesday.

The sun contributed to the problem, sending out a storm of particles that bombarded Earth and helped generate some of the ozone-destroying chemicals, according to the report in Geophysical Research Letters.

Declines in ozone over the South Pole have raised concern in recent years. They were blamed on chemicals used in aerosol sprays. Since those chemicals were widely banned, ozone levels have risen in the Antarctic.

The decline had been less dramatic in the north. But in February and March 2004, a decline of up to 60 percent was measured, according to a team of researchers led by Cora Randall of the University of Colorado at Boulder.

“This decline was completely unexpected,” Randall said in a statement. “The findings point out a critical need to better understand the processes occurring in the ozone layer.”