THE government of the state of Hesse in Germany sent shock waves across the nation when it slapped speed limits of 90 kmph on autobahns and 80 kmph on other highways, apparently to lower the emission levels of ozone-depleting gases. The measure seems a bit tough to hang on to: German motorists habitually pelt through the autobahns at an average breakneck speed of 130 kmph and the other highways at speeds of 100 kmph. These high speeds mean more pollution as fuel is burnt less efficiently.

The Hesse government's action is being termed as the longest ever trial using local measures to bring down ozone concentration. The limits were imposed on August 2 and lifted 4 days later - when the level of ozone-depleting substances fell - only to be reimposed the next day. Zealous officials even banned cars without catalytic converters and put curbs on local industrial output until the restrictions were lifted after the first round.

Vehicular pollution has been a burning issue in Germany almost for a decade now. But the government has been fighting shy of imposing tighter speed limits, fearing violent opposition from the people. The Hesse authorities have, however, oroved that the apprehensions were baseless. The people joined in the "keep ozone down" campaign enthusiastically. Most drivers took note of the "Ozone alarm" banners put across the 6-lane highways and obeyed the stricture willingly. Later, some held "no ozone parties" to celebrate the cleaner air and reduced noise pollution along the autobahns.

They certainly had reason to feel upbeat. Levels of ozone-depleting substances, such as volatile organic compounds and nitrous oxide, fell by 40 per cent as the volume of traffic dropped drastically.

The success story of Hesse has acted as a shot in the arm for the environmentalist lobby in Germany, which has now called for a general speed limit on German roads.