Voice Changes Related to Perceived Indoor Air Quality in Finnish Teachers: A Proof-of-Concept Field Study

This study examined associations between perceived indoor air quality (PIAQ) and self-reported voice symptoms in teachers, with exploratory observations on man-made mineral fibers (MMMF). Forty-seven teachers underwent within-day assessments at the beginning (good PIAQ) and end (poor PIAQ) of a workday. Clinical voice status was evaluated with laryngoscopy and the Grade-Roughness-Breathiness-Strain (GRBS) scale. Self-reported symptoms were measured with a 100 mm Visual Analog Scale (VAS) and the 30-item Voice Handicap Index (VHI). Classroom settled dust was collected on gelatin tape and analyzed by light microscopy for MMMF. No significant within-day clinical voice changes were detected, although breathiness showed a non-significant increase. Median VAS scores for voice symptoms showed no meaningful within-day change. Poorer afternoon PIAQ was associated with higher post-VAS, and longer daily exposure time co-varied with greater subjective worsening. Teachers with high VHI scores more often reported symptom worsening and poorer PIAQ ratings. Self-reported voice symptoms correlated positively with poor PIAQ and exposure duration. These findings suggest a symptom-driven pattern without evidence of environmental causality. Longitudinal studies with real-time IAQ monitoring are needed. Occupational health follow-up is recommended for teachers with persistent voice problems, with attention to vocal load.