![THE CHALK. WHAT IS CHALK? Chalk is a form of limestone that is distinguished by its relative purity and close, fine grain. Humans have been using it for. - ppt download THE CHALK. WHAT IS CHALK? Chalk is a form of limestone that is distinguished by its relative purity and close, fine grain. Humans have been using it for. - ppt download](https://images.slideplayer.com/27/9147361/slides/slide_3.jpg)
THE CHALK. WHAT IS CHALK? Chalk is a form of limestone that is distinguished by its relative purity and close, fine grain. Humans have been using it for. - ppt download
What is the effect of blackboard chalk dust on a person's health if there's exposure of the dust regularly to a human through their eyes, nose, mouth and skin? - Quora
What is the effect of blackboard chalk dust on a person's health if there's exposure of the dust regularly to a human through their eyes, nose, mouth and skin? - Quora
![From chalk dust to airborne particles: How polluted air in classrooms is affecting students - Times of India From chalk dust to airborne particles: How polluted air in classrooms is affecting students - Times of India](https://static.toiimg.com/thumb/imgsize-23456,msid-106030465,width-600,resizemode-4/106030465.jpg)