Google and eBay refuse to ban ads offering to remove car pollution filters

Internet giants say removing diesel particulate filters which reduce toxic emissions is not illegal, although driving without them is

Google, Gumtree and eBay have refused to ban adverts for a service which removes crucial pollution filters from the exhausts of diesel cars, sending toxic emissions soaring.

Over a thousand diesel car owners have already been caught after removing the filter, though experts warn the problem may be far more widespread.