The Coastal Post - July, 1996

New Ozone Holes Appearing; Public Not Being Informed

BY JIM SCANLON

A steep decline in stratospheric ozone was measured during the winter of

1994-1995 by government scientists (NOAA) operating from the top of Mauna

Loa volcano in Hawaii. Ozone values dropped below 200 Dobson Units (DU)

for the first time since measurements began at this site began thirty years

ago.

The report, which appeared in the June 1, 1996 issue of Geophysical

Research Letters, stated: "Total ozone levels this low have not previously

occurred over populated areas except on rare occasions when the edges of

the springtime Antarctic ozone hole temporarily pass over the southern tip

of Argentina."

The article was received for publication by GRL November 27, 1995.

reviewed and listed as accepted on January 10, 1996. It was not, however

updated to reflect the record breaking low levels of ozone over England (a

50 percent decline) and Northwestern Europe from January to March of this

year. (See Coastal Post , April 1996).

Of the 29 articles published in the current issue, 27 were revised before

publication, so it would not be unusual to update and the measurements for

January 1996 which were publicly available on the Internet in mid March.

For January 1995, the monthly average for the Ozone layer over Hawaii was

216 Dobson Units or about 14 percent below the norm established for the

period 1965-1981. Levels of the powerful, shorter wavelengths of

ultraviolet radiation, ultraviolet -B, which can be deadly to living

things, tripled in intensity during clear periods of low stratospheric

ozone.

What these increased levels of ultraviolet-B radiation meant for living

things on the ground could not be determined from the article, since

measurements were not made continuously-even though such measurements can

be easily and inexpensively made. Many health conscious resort hotels have

their own ultraviolet monitors to alert sunbathers of the times when UV is

normally intense.

Mauna Loa is three and a half kilometers above sea level where ultraviolet

levels are much higher than at sea level. However, even taking scattering

by clouds and air pollution, UV levels at the surface should have been

higher.

What is worrisome about the recent announcement (at least to the Coastal

Post) is that this is the first official admission that stratospheric ozone

has thinned in the sub-tropics where normal backround levels of ultraviolet

are naturally intense. Previously, all scientific consensus statements have

indicated no decline between 20 degrees north and 20 degrees south of the

Equator.

As an example, when the springtime ozone hole passes over the Southern tip

of Argentina at 55 degrees south, the suns rays are weak and the weather is

usually cold, windy and cloudy. Hawaii is 19.5 degrees north of the

equator and although it is often cloudy, the much stronger rays of the sun

have the potential for affecting people engaged in a number of outdoor

activities. And of course plants and animals are always out there.

Whether the low ozone is the result of dynamic changes in atmospheric

circulation or chemical reactions from industrial waste chemicals, or some

combination of both, is not clear. Whatever the reasons they are irrelevant

from a public health point of view, since damage to human skin from

ultraviolet-B radiation is clearly linked to the two most common forms of

skin cancer which number almost a million cases each year in the U.S.

alone.

The relationship between UVB and the most dangerous form of skin cancer,

melanoma, is less clear. Intense exposure as an adult is not linked,

however people who move closer to the equator as a child clearly acquire an

increased risk of malignant melanoma.

The authors are not unaware of the public health implications for Hawaii

(and presumably other areas at the same latitude across the globe) since

they mention, "This analysis provides an accurate method of forecasting

low-ozone, high-UV winters in Hawaii." They do not, however, give any

measurements which might help authorities determine if there is any need to

consider forecasting "high UV-winters". This is possibly a case of

messengers not wanting to be punished for bringing bad news.

On the other hand there was wide dissemination of the welcomed news of the

success of the Montreal Protocol which limited and banned the worst of

substances which depleted the ozone layer . A paper published in Science

reported that the concentration of Chlorofluorocarbons (CFCs) had peaked in

the troposphere and, all things being equal, after they had worked their

way up into the stratosphere and were eventually destroyed, after four or

five years, the ozone layer would begin to return to levels of the 1980s.

There Antarctic ozone hole, where there is no chamber of commerce and no

tourist industry to speak of , is forecast to heal halfway through the next

century.

Of course, if the stratosphere continues to cool as it has been doing, then

ozone destruction will continue, and if sulfur emissions from fossil fuel

are ever reduced, then level of ultraviolet radiation in the northern

Hemisphere will increase.

Incidentally, New Scientist Magazine, the only important publication to

mention the low ozone levels over the Northern Hemisphere this March,

recently used the term, "springtime Arctic ozone hole"-this is the mention

seen by the Coastal Post.

Jim Scanlon

199 Canal St #8

San Rafael CA 94901

415-485-0540

Fax -Manual