Indoor and outdoor elemental mercury: a comparison of three different cases

Gaseous elemental mercury (GEM) concentrations were determined in three different indoor environments: an office in a building with no indoor sources of mercury (Bldg. I), an office affected by indoor mercury emissions from an adjacent laboratory (Bldg. II), and finally, an office where an outdoor mercury spill occurred accidentally (Bldg. III). The maximum recorded indoor GEM concentrations, with the largest variation in time, were observed in Bldg. II, with a continuous indoor mercury source (lower to upper quartile 15 to 62 ng m^-3). The lowest values were recorded in Bldg. I (lower to upper quartile 3 to 5 ng m^-3), where indoor GEM levels were affected mainly by the exhaust of vehicles in the parking lot of the building. The monitoring of GEM indoors (lower to upper quartile 15 to 42 ng m^-3), and outdoors (in several heights) of the Bldg. III, revealed that the cleaning up procedure that followed the spill was not adequate. Auxiliary measurements in the first two cases were the indoor microclimatic conditions, as well as the indoor CO₂ concentrations, and in the third case the outdoor meteorological data. The exhaust of vehicles, the chemical reagents, and an outdoor mercury spill were found to mainly affect the observed indoor GEM levels. People in Bldg. II and people walking through the area, where Hg⁰ was spilled, were found to be exposed to concentrations above some guide values.