A recent CFD study into the exhaust concentration in car wakes has revealed that certain rear car spoilers (or airfoils) can either disperse or concentrate pollutants at the same height as a following cyclist's head. The study "Spoiling Air Pollution Dispersion: A Numerical Investigation of Exhaust Plume Dispersion from Cars with Rear Spoilers" authored by A. McNabola, implies possible health implications for cyclists and pedestrians that follow behind cars.

Car Wake: Streamlines released from a tailpipe

Is now the time to move to electric vehicles?

Thanks goes to the San Francisco Chronicle for reporting this study.