Environmental noise exposure in schools in São Paulo, Brazil: potential noise sources and health impacts among teachers

Noise is an important environmental and occupational health risk factor linked to sustainable development. Schools are key environments where teachers may face harmful noise exposure, yet data from low- and middle-income countries remain limited. This study assessed school noise levels and related health impacts among teachers in western São Paulo. Using a short-term repeated-measures design, daily noise measurements were conducted over one school week in seven schools, complemented by cross-sectional multilevel analyses of teacher-reported outcomes. Continuous environmental noise data were collected with calibrated Type-II sound level meters positioned at the most exposed facades, and 85 teachers completed validated questionnaires on noise sensitivity, annoyance, self-rated health, wellbeing, and sleep quality. Median weekday noise exposure reached 70.3 dB LAeq(7-19) and 94.2 dB LAFmax(7-19). Higher student density and nearby commercial activity were associated with increased noise levels. Teachers reported substantial annoyance from children's irrelevant conversations/screams (48%), road traffic (35%), and neighboring schools (31%), and more than 60% were highly noise-sensitive at work. A 10 dB increase in LAeq(7-19) was associated with 4.2 times higher odds of poor self-rated health (OR = 4.2, 95% CI: 1.3-14.0) and significantly higher noise sensitivity scores. Teacher's sleep quality and wellbeing also varied across schools with differing noise levels. Although exposure to noise in the school environment represents contextual environmental conditions and not an individual dose in indoor settings, the results suggest that teachers are exposed to environmental noise above recommended limits, with measurable health impacts. Both internal and external noise sources contribute to this burden. These results contribute to the limited evidence on environmental noise in schools in middle-income urban settings and support the inclusion of school acoustic environments within urban planning, building technologies and educational practices to create healthier acoustic environments, protecting teachers' wellbeing.