The last tenant, having removed the laminated floor, left the showroom/warehouse floor in bare cement. After thoroughly washing the cement floor, I moved in, putting up shelves resting immediately on the bare floor. Soon after, I found dust covering everything everyday even when the windows and doors are closed for long periods. When there are more people moving around, you can actually see black dust like dried powder on the floor.
Since my shelves are all in, I can either lay linoleum on the floor by cutting around the legs of the shelves or apply a coat of matt polyurethane varnish on the floor and again around the legs. Moving out temporarily is not an option as it is too expensive.
My choice is matt polyurethane. Will this work? Can it be done as the floor can only be mopped/wiped? Will it remove the dust long enough to varnish? Is this a safe long term solution? I am equally concerned about long term cement dust or fumes from varnish on the lungs.