3. Results
There were 10,464 responders participating in the web-survey. Respondents
in the air pollution module (N = 5243) and those in the
noise module (N= 5251) came from similar socio-demographic backgrounds
in terms of age, sex, net household income, financial position,
and years of education. According to the follow-up questions to €0 responses,
approximately 10% of the participants were unwilling to provide
monetary values (i.e., a “protest response”). The primary reasons
provided for registering a protest response to theWTP question regarding
reduced air pollution were (i) these costs should be included in
transportation prices (30%); (ii) the government should pay all costs
to reduce air pollution (30%); and (iii) principally opposition to
assigning a monetary value to health (20%). With regard to noise,
these figures were (i) 26%, (ii) 33%, and (iii) 20%, respectively. Approximately
50% answered, “I don't know”; these don't know responses are
described in greater detail elsewhere. After excluding respondents who
provided ‘Protest votes’ and ‘Don't know’ responses and applying the
1.5% cut-off point forWTP values, 2458 respondents in the air pollution
module and 2426 respondents in the noise module remained. Table 1
describes the prevalence of the health-, environmental-, attitude-, and
perception-related factors per country