Dead Discs, Ozone Holes and Crushed Cans

All About Atmospheric Holes, Outdated Floppies and Recycling

How thick is the ozone layer?

Mike Skram, Collegeville, MN

Murphy Illustration

Though this sounds like a simple question, the answer is actually quite complex. John Kermond, a visiting scientist with the National Oceanic and Atmospheric Administration (NOAA) in Maryland, explains that ozone layer thickness is expressed in terms of Dobson units, which measure what its physical thickness would be if compressed in the Earth's atmosphere. In those terms, it's very thin indeed. “A normal range is 300 to 500 Dobson units, which translates to an eighth of an inch-basically two stacked pennies,” Kermond says. In space, it's best not to envision the ozone layer as a distinct, measurable band. Instead, think of it in terms of parts per million concentrations in the stratosphere (the layer six to 30 miles above the Earth's surface). Concentrations of ozone vary widely according to season, but even accounting for those variations, ozone “holes” with up to 60 percent ozone depletion have been reported over Antarctica (only 100 Dobson units). Last March, low levels of ozone (220 Dobson units) were reported over the North Pole, a 25 percent drop from normal readings. In 1992 and 1993, 20 percent drops were measured in the heavily populated midlatitudes of the Northern Hemisphere (a region that includes the U.S. and Europe). Kermond, noting that Dobson readings over Antarctica have gone as low as “zero, nada, nothing,” says we should be concerned because the ozone layer acts as the “Earth's sunglasses,” shielding us from damaging ultraviolet rays. He points out that astronauts in space, unprotected by ozone, will get burned right through their space vehicle's windows, and have to limit space walks for the same reason. Australia, subject to drifting ozone holes, has the highest skin cancer rate in the world.


National Oceanic and Atmospheric Administration
Office of Global Programs
1100 Wayne Avenue, Suite 1225
Silver Spring, MD 20910
Tel: (301)427-2089

I have many 5 1/4-inch floppy computer discs that I can no longer use. Where can I send them to be recycled?

—Robyn Suderman, Fresno, CA

Since most computers sold today offer only 3 1/2-inch drives, the older floppies are piling up in storerooms across the U.S. Short of just throwing them out, however, options are limited. Several computer recyclers E contacted say they just don't get involved in 5 1/4-inch discs. Friends with older computers might want them, and schools with aging hardware are likely to appreciate a donation. Thrift stores, too, will attempt to market this still-viable product. Washington State's GreenDisk “degausses” (erases) and reformats used 3 1/2-inch discs and sends them back into the workaday world, but it reports that outmoded 5 1/4-inch discs have to be broken up and recycled for their raw plastic content. According to GreenDisk's Janna Peach, “People can send us 5 1/4-inch discs, but we have to charge 20 cents a pound, and only handle minimum orders of $10. The vinyl plastic in the discs ends up in the hands of various recyclers around the country.”


8124 304th Avenue Southeast
Preston, WA 98050
Tel: (800)305-3475

I have been looking for an electric can crusher so that I can crush my aluminum cans and store them for recycling. Do you have any idea who makes one?

—Jon Marshall, via email

As far as we can tell, there is no consumer-marketed electric can crusher. But that's no tragedy—why waste fossil fuel-generated electricity when human power will do the job perfectly well, and provide a bit of exercise in the bargain? The Jawz Company, which claims to have invented the can crusher in 1980, offers a nifty single “Can Cycler” for $9.97. One of the nicest “deluxe” models we've seen is the wall-mounted Multi-Crush Can Crusher available for $16 from Planet Natural. The all-steel unit stacks up to six cans, then feeds them automatically into the much-feared (if you're a can) Crushing Chamber. Put your recycling bin underneath, and the flattened cans will fall right in. If these low-tech solutions don't satisfy, you can always contact the Plasma Dynamics Laboratory at New York's Rensselaer Polytechnic Institute (RPI), which has, for its own whimsical purposes, invented a fiendishly complicated industrial electric can crusher. Quoting from RPI's World Wide Web homepage ( “This (somewhat) portable device boasts a 47 uF, 10 kV capacitor switched with a spark-gap. On special occasions, the cap bank is charged up and then discharged through a three-turn coil about 3 1/2 inches in diameter. A soda can placed within the coil during this process will be handily crushed…The wonder of the experience is compounded by the exceptionally loud noise that accompanies it.”


Jawz Company
PO Box 1295
Fallbrook, CA 92028
Tel: (619)728-8380

Planet Natural
1612 Gold Avenue
PO Box 3146
Bozeman, MT 59772
Tel: (800)289-6656.