One clear lesson of the Chernobyl disaster is that current systems of monitoring atmospheric radiation in much of the world are far from adequate and perhaps are not capable of providing sufficient early warning to the public, scientists say.
The main problem is that there are no standard procedures or instruments for measuring radiation and no formal reporting system.
As the Soviet accident has demonstrated, individual countries do their own airborne radiation measurements. And more often than not, they use different types of equipment, monitor for different periods of time, and report results in different units. Sweden, for example, reports readings in "bequerels per cubic meter," France in "microGreys," Britain in "microsieverts per hour" and the United States in "picocuries per cubic meter."
For all these reasons, then, scientists now concede that the actual human exposure to radiation released during the Chernobyl accident may never be known.
"We've been trying to get information about the radiation release and exposures. But it just isn't available," said Roger Ney, executive director of the National Council on Radiation Protection and Measurement.
This situation could have been largely avoided, according to medical physicist John Gofman of UC Berkeley. "Good radiation detectors are available for as little as $150. A planeload of them could have been on the way to Europe the day after the accident was reported, and we would have had a much better idea of what happened," he said.
Some inconsistency in reported results arose from differences in equipment. Radiologists in Finland noted earlier this week that their system is best because its equipment uses activated charcoal to trap gaseous compounds that may contain radioactive iodine. These compounds are not trapped in conventional filters used by most countries, including the United States. As a result, the Finns estimated, other countries actually detected as little as 15% of the total amount of radioactive iodine present.
The U.S. Environmental Protection Agency acknowledged earlier this week that its radiation monitors do not trap such gaseous compounds. EPA officials conceded that actual radiation levels in the United States were 2 1/2 to 3 times as high as EPA had been reporting. But even the increased levels were well within safety guidelines, the agency said.
Since the Chernobyl accident, individual countries have been reporting their results to the World Health Organization for compilation and dissemination, but some countries have been criticized for apparently being selective in that reporting.
No Immediate Data
WHO has no data, for example, from Poland for April 27, 28 and 29, the days immediately following the accident. Most scientists agree that the highest levels of radiation would have been released during the first two days following the explosion.
Data for many other countries during that same two-day period, such as East and West Germany, Austria, and Romania, are also missing. France has released almost no information about radiation levels.
Some scientists, such as Gofman, and some anti-nuclear organizations, such as the Union of Concerned Scientists, think that the countries closest to Chernobyl may have withheld information about exposures during those first two days to prevent hysteria among their citizenry.
Some scientists may have further muddied the data by the manner in which they have worked with it. In computing cumulative exposures to radiation in European cities, for example, EPA ignored some of the data because the agency thought the readings were too high.
Reports for May 1 in Warsaw, for example, showed readings of both 60 millirems of radiation exposure per hour and 1.5 millirems per hour. But EPA discarded the higher figure, a spokesman said, "because it didn't fit in with the rest of the data and we think they might have made a mistake."
That day would, however, have marked the period of highest exposure, and the levels would have been expected to drop sharply later.
Times staff writer Tyler Marshall in London contributed to this story.