WHAT exactly lies behind the concrete walls surrounding the Institute for Research into Precision Instruments in an anonymous district of North Moscow is a state secret. But what comes out, pumped into the Chermyanka creek through a concrete pipe, steams ominously in the cold air and is poisonous.
The institute was identified as a major polluter when local activists trying to save the river had the waste water tested. But the factory is only one among thousands of culprits in a city that has never cared much about ecology.
From the ancient power station whose belching chimneys overlook the Kremlin to the sprawling plant that produces Zil limousines and trucks, the Russian capital is an environmental disaster area.
Now city officials and local pressure groups are using Russia's new economic and social freedoms to try to get rid of big offenders. City hall is turning its back on Moscow's heavy-industry past and dreaming of a modern metropolis thriving on commerce and services. Grass-roots activists, meanwhile, are working on the more immediate problem of making their neighborhoods habitable.
By July 1, under a Draconian plan drafted by the mayor's office, two-dozen of the most egregious ecological offenders will have cleaned up or closed down.
''These are old factories with no future, and they are certainly a hindrance to the city's development,'' says Yevgeny Panteleyev, head of the city's Department of Industry.
If the companies don't comply with the ruling, Mr. Panteleyev warns, ''we are going to force them out by means of rent.''
What he means is that the city will double their rents every three months until they move out or go broke.
''We are going to start with the factories that simply cannot be where they are, like a ceramics plant in the middle of a residential district, and the asphalt and cement factory that is in a national park,'' Panteleyev explains.
WEAPONS new to Russia, such as the market force of rent, will be more effective than the old battery of Soviet laws and edicts that everybody ignored, officials hope.
There was no such thing as rent until last year in Moscow: The state had always owned all land and buildings. That meant that it cost as little to run a factory on prime real estate downtown as it did outside the city.
Nor were there any zoning laws that might have kept noxious industries out of the city center. Zoning is a concept that Panteleyev says he is only now introducing to city planners.
And although the Soviet government began to order industry out of the capital 20 years ago, ''as a rule, those orders were not carried out,'' Panteleyev says. ''It generally turned out that there was not enough money to build new plants, and since there was no replacement, the old ones couldn't be closed.''
It has been 10 years since Asphalt and Concrete Factory No. 3 was first told to leave Losiny Ostrov, a silver-birch forest in northeastern Moscow that has been declared a national park. It still operates there.
When ''outrages'' like that have been dealt with, Panteleyev says, he will expand his list of targets to about 100. All in all, he reckons, about 600 factories will have to leave the city unless they install pollution controls.
Some activists doubt that much will come of this program. For a start, says Valery Sevostyanov, a member of the Moscow city council, more than 75 percent of the air pollution here comes from vehicle exhaust, about which nothing is being done.
At the same time, complains Natalya Kirpichova, who runs the Chermyanka Ecological Society, ''Where are they going to take the industry? They are just going to move it outside the city, where it will still go on polluting.''
Dr. Sevostyanov hopes that moving enterprises will make them cleaner. ''In most cases, the technology is so old that the only solution is to close down the factory and start from scratch elsewhere,'' he says. ''So new technology will be built into the new factories.''
The decommissioning of the Ducat cigarette factory in downtown Moscow and its relocation to the suburbs is a positive case study:
The factory dominates a shabby street where the air is heavy with tobacco dust. The factory was built in 1893, and the city grew up around it.
''This is the wrong place for a cigarette factory,'' says Dan Terry, the operations manager brought in by Liggett, an American tobacco company that has teamed up with Ducat to modernize its operation.
Liggett-Ducat is converting its decaying premises -- building by building -- into modern offices and renting them out to tenants like Citibank, Morgan Stanley, and other prestigious firms.
With the rental earnings, the company is building a new production facility on the edge of Moscow ''where the equipment will be much more modern, and the dust systems are 99.9 percent clean,'' Mr. Terry says.
Liggett-Ducat is not moving right out of the city, explains Vice President Olga Grigorieva, ''because that would have meant transportation problems for our employees. To have built a factory 60 kilometers [37 miles] outside Moscow would have deprived more than 1,000 people of their jobs.''
That highlights the social problems that are bound to follow the city's drive to force industry out. Five thousand people work in the first 24 companies slated to be expelled, Panteleyev says, and some companies that deserve to be expelled have been saved because of the number of people who work for them.
''We look very carefully at what the companies produce, how many employees they have, what the job prospects in the neighborhood are like,'' Panteleyev says. ''We are not just closing factories down without caring.''
BUT there is a human cost to keeping them open, too. When Dr. Kirpichova's Chermyanka Ecological Association ran tests two years ago on 500 nine-year-old children born in the Biberevo district of Moscow, where the Chermyanka runs, 490 of them were diagnosed with unacceptably high concentrations of heavy metals in their bodies.
When another 11 children were tested for mercury, the least affected was diagnosed as having three times the acceptable level of the poison in his system. The most affected had 30 times the level declared acceptable.
Previous governments, both national and municipal, did nothing. And even though the present authorities in Biberevo have not shown much sympathy or inclination to act, either, Kirpichova says, her group now has a detailed ecological study of the district to use in their battle.
''The scientists divided our area into the bits that are an ecological catastrophe, where things are beyond redemption, and a disaster, where something can be done about it,'' Kirpichova says.
''We are trying to prove that our river can still purify itself,'' she adds. ''We want to stop things before they get beyond the point of no return.''