UNLEADED ADJECTIVE (ENVIRONMENT)

Of motor fuel: not containing added lead. Etymology: Formed by adding the prefix un- to leaded. History and Usage: Unleaded motor fuel has been available since the sixties, but did not really come into the news in the UK until the late eighties, when motorists were actively encouraged to have their vehicles converted to use it. This encouragement, which included price incentives, arose from the high profile of the green movement and widespread concern about the effects of pollution on the atmosphere: unleaded fuel produces less harmful exhaust emissions and reduces engine deposits. This kind of fuel is also called lead-free (see -free); both adjectives can be used on their own, as though they were nouns meaning 'unleaded fuel'. Reader offers...included free weekend breaks, the prize of a house in France and the post-Budget free offer to convert readers' cars to unleaded petrol. Today 12 Mar. 1990, p. 2 Running a car will cost you more this year--but if you're 'environment-friendlier' the change won't hit as hard. Duty on petrol went up by about 10 per cent--an extra 11p per gallon for leaded petrol, 9p for unleaded. Which? May 1990, p. 249 The chain claimed its petrol is now Britain's cheapest at 198.7p a gallon for four star unleaded. Sun 20 Oct. 1990, p. 2