NOAA 98-011

Contact: Barbara McGehan                  FOR IMMEDIATE RELEASE
         James Butler                     2/19/98
      

Despite a ban on the production of ozone-depleting halons by developed countries, the compounds continue to increase in the atmosphere according to a new study by the Commerce Department's National Oceanic and Atmospheric Administration.

Measurements by scientists at NOAA's Climate Monitoring and Diagnostics Laboratory in Boulder, Colo., indicate that three bromine-containing fire extinguishants, halons H-1211, H-1301 and H-2402 are still being released into the atmosphere in crucial amounts.

The findings are reported in the January 20 issue of the Journal of Geophysical Research and are the result of a ten-year analysis of air samples from eight remote climate monitoring stations, which were sampled on a biweekly and /or monthly basis, and seven research cruises in the remote ocean. A companion paper, by Wamsley, et al, reporting similar results of measurements from high-altitude aircraft, which calculated total bromine in the lower stratosphere, also appears in the same issue.

Scientists are concerned about the increase in halons because bromine, an element in the halons, is 50 times more efficient at depleting ozone in the atmosphere than it's nearest rival, chlorine, a component in chlorofluorocarbons (CFCs), and because the gases last a long time in the atmosphere. "Given the current atmospheric record and the reported amount of halon produced before the ban on production, emission of one of these compounds could continue for another 40 years," scientist and lead author James Butler said.

"These increases are significant and of concern because of the efficiency of bromine in depleting stratospheric ozone and because of the long atmospheric lifetimes of these gases," said Butler. According to Butler, there are as yet no suitable substitutes for all halon uses, some of which are critical. The main sources of the compounds are from stockpiles of halons produced before the ban on production and from developing nations, such as China. In fact, China alone generated almost 90% of the global production of halon in 1994. Continued increases in production in developing countries are allowed within the Montreal Protocol until the year 2002, at which time they will have to freeze production at the 1995-97 levels. The Montreal Protocol is an international agreement to limit ozone-damaging compounds that was originally signed by the United States and 22 other nations in 1987, and subsequently revised and amended.

Another concern is the reported decline in total equivalent chlorine in CFCs that was reported by the same NOAA scientists in the journal Science several years ago. That report was regarded as a sign that the recovery of the ozone layer would soon begin and an indication that the Montreal Protocol was working. However, according to Steve Montzka, lead author of that manuscript and a co-author on the current one, "The halons are partially offsetting the decline we reported a few years ago. By the year 2005, if halons continue to increase in the atmosphere, the total amount of equivalent chlorine (chlorine + bromine) will no longer be decreasing as we observed a few years ago." This could cause the recovery of the ozone hole to slow down because even though the amount of bromine present in the atmosphere is smaller than chlorine, it is much more destructive of ozone. Will halons continue to go up? Possibly. "We believe there's still a lot of halon out there waiting to be used. And there are no substitutes at present," says Montzka.

For more information on this topic, consult the Climate and Monitoring Diagnostics Laboratory home page at http://www.cmdl.noaa.gov/noah