The Hudson station post office in northeast Modesto was evacuated this afternoon after employees reported an irritating odor in the building, officials said.
The Stanislaus County hazardous materials crew went into the building to look for a canister of pepper spray or similar irritant. The odor dissipated and no source was found.
The building reopened after emergency crews finished their search.
Postmaster Cory Sandobal said the odor might have come from a dog repellent that letter carriers bring with them on their routes, but he said there was no evidence of that being the source of the odor.