People living outside London could end up suffering from higher levels of pollution thanks to the introduction of the capital's Low Emission Zone (LEZ).
A survey conducted by the Freight Transport Association (FTA) reveals operators are planning to relocate their older, more polluting trucks from London to other depots.
Natalie Chapman, regional policy manager for London at the FTA, says national firms are looking at swapping older vehicles, currently based in London, with newer ones operating elsewhere, before the LEZ starts next February.
Chapman adds: "What the scheme is doing is pushing older, more polluting vehicles outside London."
TfL admits a 2006 survey found that some firms would reorganise their fleets so non-compliant vehicles would be used outside London.
It adds: "The air quality benefits outside London resulting from vehicle renewal and modification are expected to outweigh the negative impact of this reorganisation."