The European Region of the World Health Organization (WHO) recently published revised recommendations for transportation noise exposure intended to limit adverse health effects. WHO's newly recommended "safe" limit for aircraft noise exposure is about an order of magnitude lower than the limits currently adopted by most European countries. WHO defines "safe exposure" as the level corresponding to an annoyance prevalence rate of 10% highly annoyed. The revised recommendations are based on a limited selection of post-2000 publications. About half of the cited studies rely on nonstandard questionnaires, respondent selection, and definitions of annoyance prevalence rates which over-estimate annoyance. A re-analysis of a larger and more representative selection of studies that relies on standard procedures shows that no meaningful changes in prevalence rates of high annoyance with aircraft noise have occurred and that existing evidence does not support WHO's revised recommendations.