On September 22, 2014, the Michigan Department of Community Health (MDCH) and the Washtenaw County Health Department (WCHD) requested EPA assistance at a residential mercury release in Ann Arbor, Michigan (NRC # 1096105). The agencies observed elemental mercury adjacent to the furnace at the residence. Initial air monitoring detected mercury vapor concentrations of 40 – 50 micrograms per cubic meter of air (ug/m3) near the furnace and 30 – 34 ug/m3 in the basement bedroom; the acceptable mercury vapor concentrations for most sensitive persons is less than 1 ug/m3. OSC Nightingale and EPA contractors mobilized to the site to begin emergency response actions.