Rather than tackle the source of London's abysmal air quality (motor traffic), the Mayor is trialling a dust suppressant technology.
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.
Needless to say, this ain't gonna be cheap. The trial alone is costing £300,000, and will only treat two key routes, the A501 (Euston Road/Marylebone Road) and the A311 (Victoria Embankment).
Meanwhile, the Mayor has delayed the expansion of the Low Emission Zone, abolished 6-monthly emissions checks for black cabs, and the changes to the Congestion Charge will ensure more traffic and exempt more diesel vehicles (which emit more particulates than other fuels). Additionally, transport fare rises will likely force more people into their cars.
London needs to de-carbonize. London needs better air quality. These two goals need to be addressed by promoting sustainable transport and reducing motor vehicle use. The Mayor seems intent on doing the opposite.