Not sure what your options are out there on the left coast, but in Tennessee we have several products made by Ortho and others that are in granular form. The stuff looks like saw dust and you spread it on the yard. I have pets so I treat the yard at least a couple times a year. Very rarely ever see a flea. I think you could spread this in the shop. Some of these products have markedly less odor than others so check first.
In any case, if you have to eventually bomb the buggers, it would be very prudent to treat the perimeter of your shop, outside with a heavy dose of the granules. Keeps them from coming back. Kinda like having a chemical moat around the shop.
Also, if chemicals turn you off, you might try covering the floor with red cedar shavings. Fleas hate red cedar.
-- Michael :-{| Diapers and politicians both need to be changed often; and for the same reason.
