Indoor Air Quality and Exposure Characterization in Operational Waterpipe Cafés: Field Measurements of Particulate and Volatile Pollutants in Al-Madinah Al-Munawwarah

Abstract

Waterpipe cafés represent combustion-dominated indoor environments where tobacco heating and charcoal burning generate complex mixtures of airborne pollutants. Despite the widespread presence of such venues in Saudi Arabia and globally, quantitative field measurements describing real-world exposure conditions remain limited, particularly in the Gulf region. This study characterizes indoor air quality in five operational waterpipe cafés in Al-Madinah Al-Munawwarah through direct measurements of particulate matter (PM₂.₅ and PM₁₀), total volatile organic compounds (TVOCs), and formaldehyde (HCHO) during peak occupancy periods on weekdays and weekends. Substantial spatial and temporal variability in pollutant concentrations was observed across venues, largely reflecting differences in smoking intensity and ventilation effectiveness. Mean weekday PM₂.₅ and PM₁₀ concentrations reached 285.5 ± 149 μg/m³ and 301.6 ± 156 μg/m³, respectively, while weekend TVOC concentrations averaged 0.50 mg/m³. In multiple instances, measured particulate and volatile pollutant levels exceeded international health-based guideline values, indicating elevated exposure potential under high-use conditions. Formaldehyde concentrations remained below short-term reference thresholds. The findings identify waterpipe cafés as significant indoor sources of fine particulate matter and volatile pollutants. This study provides region-specific evidence supporting the need for stricter indoor air quality regulations in waterpipe café environments. The results contribute to advancing national priorities in public health protection, environmental sustainability, and urban environmental management within Saudi Arabia.