Higher carbon emissions from longer journeys are undoing the good work created by better vehicle efficiency, research has shown.
Transport - excluding international aviation and shipping - now accounts for about 19% of total European greenhouse gas emissions, after growing 28% between 1990 and 2007.
A study by the European Environment Agency (EEA) showed road transport emitted the highest levels of nitrogen oxides, and was the second largest contributor of pollutants forming fine particles in 2007, despite overall reductions in air pollutant emissions.
The agency suggested the reasons behind long-distance travel should be considered to reduce future totals.
Professor Jacqueline McGlade, EEA executive director, said: "Over the last 10 years we have concentrated on measures to improve mobility whilst decoupling transport emissions from economic growth.
"Today, we can see that the extensive investment in transport infrastructure has enabled us to travel further to meet our daily needs, but has not led to a decrease in the amount of time that we are exposed to noise, congestion and air pollution.
"In the future we will need to focus not only on the mode of transport, but also the reasons why people choose to travel, because ultimately mobility is inextricably linked to our quality of life."
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