Dataset for study: Cleaning up our acts: Psychological interventions to reduce engine idling and improve air quality

List and descriptions of the variables included (the same information appears to tab2 of the Excel document)

Observation - observations numbered

Condition - "experimental condition: 0 = baseline, 1 = social norm, 2 = outcome efficacy, 3 = private self-focus"

simple_baseline - dummy contrast code used to assess the effect of Number of vehicles in the Baseline condition

simple_norm - dummy contrast code used to assess the effect of Number of vehicles in the Social Norm condition

simple_efficacy - dummy contrast code used to assess the effect of Number of vehicles in the Outcome Efficacy condition

simple_selffocus - dummy contrast code used to assess the effect of Number of vehicles in the Private Self-Focus condition

Location - location at which data were collected, 1 = Location 1, 2 = Location 2

Date - date of observation (MM/DD/YYYY)

Date_num - date of observation numbered from 1 (1st observation day) to 17 (last observation day)

Session - represents one barrier drop, numbered from 1 for each observation day (used for multilevel grouping)

Vehicle_type - type of vehicle, 1 = car, 2 = bus, 3 = lorry, 4 = motorbike, 5 = service vehicle, 6 = van, 7 = taxi

Number_vehicles - number of vehicles queuing at one location, for each barrier drop (session)

temperature - average temperature measured for the duration of the barrier drop

humidity - average humidity measured for the duration of the barrier drop

NO2 - average NO2 concentration level measured for the duration of the barrier drop

O3 - average O3 concentration level measured for the duration of the barrier drop

PM25 - average PM2.5 concentration level measured for the duration of the barrier drop

logNO2 - logarithmic transformation of NO2

logO3 - logarithmic transformation of O3

logPM25 - logarithmic transformation of PM25

Engine_off - whether engine is on or off, 0 = engine on, 1 = engine off