Investigation of particulate matter performances in relation to chalk selection in classroom environment

Abstract

This study aims to understand dust generation in classroom indoor for different chalk varieties and their potential doses to receptors in correlation with their physicochemical properties. Two representative chalks of extruded calcium carbonate and moulded gypsum type (total four) were used for writing on ceramic and wooden boards. Chalks were characterized using analytical techniques. Investigation of Particulate Matter (PM): PM_2.5, PM₁₀ and Total Suspended Particulate (TSP) concentrations in classroom air generated during the writing and wiping with chalk and board system was done. Dust collected beneath the board was analyzed for particle size distribution. Calcium carbonate made dustless chalks generate less PM during writing and wiping. They are quick settling and non-interacting with receptors, and deliver better utilization of material as compared to gypsum chalks. Physicochemical properties of the chalk constituents were invoked to explain the dust generation and its impact on the user. Surprisingly, dustless chalk made from Gypsum cannot be called really as dustless because of more PM emissions. The age-specific average potential dose for both PM₁₀ and PM_2.5 is higher for gypsum chalk as compared to the calcium carbonate chalks. The highest dose was estimated for the children in the age group of 6–11 years.