I would definitely seal the floor. Concrete basement flooring (or any concrete) will continually "off-dust" for its entire life. The floor will never not be dusty.
There is a great sealer called Trojan Masonry Sealer.
- From their website: "easy to apply and is non-toxic, non-flammable, non-hazardous, low VOC (11.67 g/L) and water soluble."
- They are based on the East Coast and should have suppliers in your area.
I know you are planning to put down tile as well. I would still seal the concrete. Air flows (like water) in mysterious and unseen ways. It is best to seal what you can, especially if there are people living in the house who are sensitive.
Before you choose a type of sealer from the supplier, tell them you are planning to tile over it -- just to make sure there is no conflict of products.
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Check our remodeling a basement Q&A to see what other homeowners and contractors are saying about concrete, tile, etc.