Poking around the Dyson website, I found this page about their fancy Dyson Digital Motor. It includes the sentence
And no carbon brushes means no carbon emissions.Seriously? WTF? I don't think the climate talks in Copenhagen were held to reduce the amount of carbon falling off the carbon brushes in electric motors. These days "carbon emissions" means CO2 and unless you run your house on solar power, anything that draws power from the mains has carbon emissions.
Apparently these motors are very efficient, which will reduce CO2 emissions, but someone in the marketing department had to push it beyond the truth. Ah well, I still like them.