And it shall become fine dust is literally “and it will be [or, become] to dust.” The preposition “to” is often used with a noun following the verb “to be or become,” to mark the result of that change. Fine dust is one word meaning dust in powdery form, like soot, which could easily be blown by the wind over all the land of Egypt. Soot, of course, comes from something that is burned (see “ashes” and the comment at verse 8), while fine dust comes from dry soil. Good News Translation‘s “They will spread out like fine dust” is a possible interpretation in this context, but such a distinction in meaning, if intended, would likely have been expressed more clearly. The Hebrew preposition used here does not normally carry the meaning of “like.” (But see Jerusalem Bible, “It shall spread like fine dust.”) Contemporary English Version has a good model, “The ashes will blow across the land of Egypt.”

And become boils is literally “and it will become to boils” (similar to the expression discussed in the preceding paragraph). The word for boils means a hot or inflamed swelling of the skin. Good News Translation‘s “will produce boils” is probably the intended meaning rather than suggesting that the dust would actually turn into boils. One may also express this as “will cause boils [or, sores] to break out.” The word for sores is found only here in the Old Testament, and the verb for breaking out means “to sprout or bloom.” So breaking out in sores suggests the meaning of “open sores,” or “festering boils” (New English Bible). Other possible renderings are “pustules” or “ulcerated boils,” meaning boils or sores that have pus in them.

On man and beast includes all humans and all animals, both wild and tame. Throughout all the land of Egypt simply adds emphasis to the extent of the plague. It is an intentional exaggeration to include all Egyptians, but it apparently did not apply to the Israelites or to their animals.

An alternative translation model for this verse is:

• The ashes, like fine dust, will blow all over the land of Egypt. They will cause people and animals everywhere to have ulcerated [or, festering] sores.

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .