Psychological messages can cut engine emissions


Something as simple as carefully-worded signs can cut the number of drivers leaving engines idling by 38% and lead to a boost in air quality.

Research by University of Kent psychologists at St Dunstan’s and St Stephen’s level crossings in Canterbury last summer shows motivating messages at the two sites cut emissions by the equivalent of taking 1,044 cars off the road for a year.

The research, which was funded by Canterbury City Council following a successful grant bid to the Department for Environment, Food and Rural Affairs (DEFRA), assessed 6,528 vehicles arriving at the level crossings where air quality values tended to exceed national and EU recommended thresholds at various times most days.

They tested the effects of three different signs that amplified existing signs that requested drivers to switch off their engines, by asking them to “join other responsible drivers”, “to think about their actions”, or to “improve air quality in the area”.

Project leader Professor Dominic Abrams said: “This project successfully used social psychology to persuade more drivers to turn off their engines, bringing benefits for everyone in the area, including the drivers themselves.

“Translated into concrete consequences for Canterbury, we estimate that a 38% reduction in idling would prevent the emission of 4,920 tons of CO2 (Carbon Dioxide) per year, equivalent to taking 1,044 cars off the road for an entire year or to saving 2.1 million litres of fuel.

“If the same were achieved at the 1,500 level crossings across public highways nationally the annual impact on national air quality would be equivalent to removing nearly 470,000 cars from our roads.

“We believe that this approach could also easily be adapted for areas where engine idling is common, such as schools, and areas where there are long queues and delays associated with traffic lights.”

Leader of Canterbury City Council, Cllr Robert Thomas said: “Improving air quality in the district is a major focus area of the council and research like this is vital to that work.

“The results clearly show that the right messages in the right locations can be really effective in reducing the number of people idling, which is one of the main contributors to poor air quality in our city.

“These new signs are just one of many things we’re doing to tackle air quality which most recently includes the introduction of nine electric vehicle charging points and plans for a new cycle hub at Station Road West.”

The council’s Policy and Resources Committee will meet on 17 July to discuss climate change, environmental issues and plans for further improvements.

Read the full ‘Can Car Engine Idling Be Reduced Using Persuasive Messages?’ report. 

To find out more about what the council is doing to tackle air quality visit