The 11-point scale for the level of annoyance was dichotomized into “very annoyed” or “not annoyed”; scores of 8–10 were categorized as “very annoyed”, following on the ISO convention (ISO/TS 15666:2003).
This was also the case for annoyance by air pollution, and the level of concern by noise and air pollution. The 5-point scale for the perception-related variables was converted into smaller “agree, neutral, or disagree” or “yes or no” scales. The 3-point awareness scale was converted into a “yes or no” scale in which those who selected “very much aware” were categorized as “yes”. Since the percentages were rounded in this study, summing percentages (%) may not add up to 100%. All of our analyses were performed with IBM Statistics SPSS Version 19.