As shown in Table 3, most of the significant variables in the basic model remained associated with WTP estimates in the extended model. The additional variables included in the extended models (that significantly affected all three WTP estimates levels) were environmental concerns, annoyance at home by road-traffic air pollution (except for the general extended model), respondent sensitivity to air pollutants
(except for the LE extended model), respondent ability to relax in polluted locations, and the government's attempts to reduce pollutants (except for the LE extended model with a “neutral” answer). Factors that did not significantly influence the WTP estimates were respondent awareness of health risks, air pollution concern and respondent belief that policies to reduce pollutants were intended to improve wellbeing.