Zurich — When Michigan's Guardian Industries decided to build a glass factory in the sleepy Swiss town of Schaffhausen, there was little sign of the troubles ahead. Retrenchments in the depressed Swiss machine industry had left unemployment soaring in the region, and the town fathers were overjoyed at the advent of a dynamic American company offering jobs.
Then the news broke that Swiss forests were dying, caused by what is believed here to be a combination of air pollution and acid rain. Overnight, saving trees became a prime concern.
Some 7,800 people signed a petition to stop the United States's fourth largest flat-glass company from building in Schaffhausen's industrial area. German communities near the border town are protesting. The Schaffhausen High Court will decide if the factory can be built as planned, but experts disagree over the acceptable degree of polluting emissions.
''No one cared before the dying woods phenomenon broke. Now, there is such a panic around,'' exclaimed Schaffhausen town councilor Paul Harnisch, who protests he is as much a nature-lover as anyone else in this nature-loving town.
But, he stresses, one has to be reasonable. The factory means jobs. There is no factory without emissions. It just has to be as environmentally friendly as possible. He thinks Guardian Industries is.
The Swiss dispute throws up a question which is troubling Central European authorities generally: What number of jobs is worth how much pollution?
Zurich's financial biweekly Finanz und Wirtschaft asked in a recent story on widespread opposition to the plant: Will it be possible in future to build new factories in Switzerland or is the country finished as an industrial center?
The Guardian factory would produce some 500 tons of glass annually - and approximately 1,200 tons of nitric oxide. Mr. Harnisch says construction of a 90 -meter-high furnace tower would keep environmental effects at an acceptable level.
Guardian executive vice-president Thomas Gaffney claims his company is building the ''most pollution-free plant possible.'' He points out that the Schaffhausen melting furnace will run on natural gas, eliminating fuel-related sulfur emissions. Furnace design, production process, and equipment are intended to keep pollution to a minimum.
The World Wildlife Fund's Schaff-hausen division president, Hans-Georg Bachtold, says any increase in his area's pollution is too much. Some 36 percent of trees in the Canton of Schaffhausen are diseased or dying.
''We are just as interested in jobs as anyone else. But the degree of air pollution must be reduced. Adding a glass factory certainly will not,'' he protests.
At present Europe has a flat-glass surplus, but glass is heavy and expensive to ship long distances. Schaffhausen provides easy access to Switzerland, southern Germany, Austria, and Italy.
Guardian is counting on a marked increase in the demand for glass by the time the Schaffhausen factory should open in 1986-87, says Gaffney.
What it did not bet on was an environmental wave that could be more powerful than the lure of 200 needed jobs.