Chalk dustfall during classroom teaching: particle size distribution and morphological characteristics

Area of Science:

• Environmental Science
• Occupational Health
• Materials Science

Background:

• Traditional chalk use in classrooms generates airborne particulate matter.
• The size and composition of chalk dust can impact respiratory health.
• Different chalk formulations and board surfaces may influence dust generation.

Purpose of the Study:

• To compare the particle size distribution of dust from dusting and non-dusting chalks.
• To evaluate the potential health risks associated with chalk dust exposure in classrooms.
• To analyze the influence of board surface texture (rough vs. smooth) on chalk dust characteristics.

Main Methods:

• Collection of settled chalk dust particles on Petri plates over 30 minutes during teaching.
• Analysis of particle size distribution using established methods.
• Examination of chalk dust morphology via scanning electron microscopy (SEM).
• Assessment of chalk compressive strength to understand particle generation mechanisms.

Main Results:

• Non-dusting chalks generated a higher proportion of fine particles (<4.5 micrometers respirable, <11 micrometers thoracic) compared to dusting chalks.
• Despite lower overall dust mass, dusting chalks produced more respirable and thoracic particles per unit time.
• SEM revealed elongated particles in dusting chalk dust, correlating with lower compressive strength and longitudinal fracture patterns.

Conclusions:

• Dusting chalks are potentially more hazardous due to higher generation of fine, respirable particles.
• Classroom chalk dust composition and particle size are critical factors for assessing inhalation risks.
• Understanding chalk properties and usage is essential for mitigating classroom air quality issues.