I wouldn't use saw dusts personally. I know old folks that do, but it is known to cause craw impaction, not to mention when it gets wet, and it will, it really holds moisture. You want your chicks to stay good and dry. I like corn cobb litter, it drains well and there is no risks with such as dust, or impaction concerns. Most people on here choose to use pine shavings. They are cheaper than what I use. You have to make sure that you get large shavings. Look at the bag and you shouldn't see noticeble saw dust, it should be big pieces.
Editing to say if you use shavings to make sure they are pine, or aspen. Ceder oil is toxic to chickens. The process of turning it into shavings releases the oil.
Sawdust and cedar are toxin to small animals...not only the respiratory issues from the dust but, when urine is mixed with them, there is a sort of chemical reaction that causes a sort of toxic fume for the little guys.