I had this Crayola Dustless Chalk bought for sometime now and had my kids use them just recently.
It may look just like the ordinary chalk but choosing this over the cheaper and ordinary one does have benefits. Aside from the fact that it writes smoother without scratch, it also doesn't break easily.
Having a child with skin asthma ain't easy especially if she loves to doodle a lot. My elder daughter was advised by her dermatologist not to directly hold chalks because it leaves particles in her hand which causes it to itch and develop rashes. In addition, ordinary chalk's particles floats in the air which we get to inhale. With a dustless chalk, this can be avoided. Its particles are too heavy which directly falls to the ground instead of floating. My elder daughter didn't complain of itching after using it. She enjoyed drawing for her younger sister, actually.