Clean air trial launches in London

A new dust suppressant trial was launched today (November 12) by Transport for London (TfL) with a demonstration in the east of the capital.

The trial is part of the Mayor of London’s plans to improve the quality of the air in London in the most polluted areas.

London is currently in danger of breaching European Union legal limits for particulate matter PM10 at certain hotspots in the city where traffic levels are high.

The trial is to concentrate on two key corridors: the A501, which includes Euston Road and Marylebone Road and the A311, Victoria Embankment.

The procedure involves sweeping roads and then spraying them with a solution of calcium magnesium acetate (CMA), which sticks to particulate matter to prevent it re-circulating into the air.

The particulates remain on the road surface and are then washed away either by rain or road cleaning.

CMA is a biodegradable saline solution which has not been found to be harmful to human health.

Current trials are experimenting with the amount that needs to be used to get successful results. So far, a solution containing 10 grams of CMA per square meter sprayed evenly on the road surface is being tested. Higher amounts make the surface slippery for vehicles.

During the trial, PM10 levels will be monitored by the London Air Quality Network, which has 100 monitoring sites. TfL hopes that PM10 will be reduced by 10-20 %, as has resulted in similar trials in Europe.

The Mayor of London, Boris Johnson said: “We expect this new measure to have an immediate impact on air quality in the most polluted areas of central London.”

The trial, budgeted at £300,000 will last for six months and results will be reported in autumn 2011.

Alison Brown

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