Impact of indoor environment quality on autistic behaviours in autism schools of Saudi Arabia.

Indoor Environmental Quality (IEQ) strongly influences students' learning outcomes, yet its impact on autistic students remains underexplored. This study investigates the relationship between IEQ parameters and behavioural outcomes of 37 autistic students (DSM-5 Levels 1-2) aged 5-12 years attending two autism-specific schools in Saudi Arabia across winter and summer periods. IEQ parameters - temperature, relative humidity, carbon dioxide (CO2), particulate matter (PM2.5 and PM10), sound level, and illuminance - were continuously monitored, alongside behavioural observations. Behaviour and sensory reactivity were assessed using the Behavioural Assessment of Classroom Sensory Scale-School Observation System (BASC-SOS) and the Sensory Assessment for Neurodevelopmental Disorders (SAND), which capture external behaviours (movement, vocalisation, and task engagement). Repeated measures correlation analysis revealed significant relationships between PM10 concentration and both adaptive (p = 0.04) and maladaptive behaviours (p = 0.05), sound levels and maladaptive behaviours (p = 0.05), and relative humidity and adaptive behaviours (p = 0.03). CO2 levels in hypersensitive autistic students and both adaptive (p = 0.05) and maladaptive behaviours (p = 0.01). Pupils demonstrated heightened sensitivity to elevated CO2 and noise fluctuations, highlighting the compounded sensory effects of air quality and acoustics. These findings underscore the need to tailor environmental conditions in autism-specific educational settings to accommodate the sensory reactivity of autistic students. The study not only advances foundational knowledge of IEQ's impact on autistic behaviour but also offers practical implications for designing educational environments that foster both academic engagement and student s' well-being.