There is increasing evidence that traffic fumes cause heart disease, respiratory disease, strokes, neurodegenerative conditions, early death, and now dementia. Ten years ago, in No Idle Matter, I wrote that traffic control multiplies harmful emissions by a factor of four. Engineering lecturer at the University of Surrey, Prashant Kumar, says the multiple is as high as 29 – no surprise if you’ve endured the interminable hold-ups from innumerable traffic lights on roads such as the A24 in Balham. Despite the evidence, and proof that sociable filtering without regulation more than halves journey time and emissions, traffic authorities do nothing. Corporate man’s laughter, or corporate manslaughter?