Cleaning up our acts

Dominic Abrams, Fanny Lalot, Tim Hopthrow, Anne Templeton, Ben Steeden, Hilal Özkeçeci, Hirotaka Imada, Sarah Warbis, Dominic Sandiford, Rose Meleady, Emily Fell, Zoe Abrams, Alice Abrams, Qing Ngan Xue, Stephanie Celina, Alize Tanyeri, Molly Gammon, Benjamin Abrams, Liliann Fischer, Sophie Drysdale, Riska Dewi, Ana Leite, Ashley Mills, Stephen Peckham

OAI: oai:purehost.bath.ac.uk:publications/b795ce68-e215-46bc-8db5-38c1fcf2bb7e • DOI: https://doi.org/10.1016/j.jenvp.2021.101587

A large-scale field experiment tested psychological interventions to reduce engine idling at long-wait stops. Messages based on theories of normative influence, outcome efficacy, and self-regulation were displayed approaching railway crossing on street poles. Observers coded whether drivers (N = 6049) turned off their engine while waiting at the railway crossings (only 27.2% did so at baseline). Automatic air quality monitors recorded levels of pollutants during barrier down times. To different degrees, the social norm and outcome efficacy messages successfully increased the proportion of drivers who turned off their engines (by 42% and 25%, respectively) and significantly reduced concentrations of atmospheric particulate matter (PM2.5) 2 m above ground level. Thus, the environment was improved through behavior change. Moreover, of both practical and theoretical significance, there was an ‘accelerator effect’, in line with theories of normative influence whereby the social norm message was increasingly effective as the volume of traffic increased.