In the race to combat urban pollution, the Japanese are off to a flying start.
Fighting the battle against automotive emissions is industrial group Mitsubishi. Its materials division is testing a special type of paving on an Osaka roadside which cleanses the air of nitrogen oxides, one of the main pollutants from traffic.
The cement paving contains titanium dioxide in its upper layer which, in sunlight catalyses a reaction which absorbs the nitrogen oxides. Laboratory tests by Mitsubishi last year showed that the blocks removed 80% or more of the NOx fumes.
Mitsubishi claims the paving is as strong as other paving materials and costs are not expected to be much above those of traditional high quality blocks.
But the effects of the weather on the process remain an obstacle. Tests show that the NOx-removing ability of the paving decreases as the air moisture increases.
Mitsubishi will run its tests until next year but interest has already been shown by councillors in Edinburgh. Keen to cut vehicle pollution levels in Scotland’s capital, they are monitoring the Osaka trials. However, Liberal Democrat councillor Moyra Forrest said: `Our weather may restrict its use to a seasonal basis’.