At room temperature, elemental (metallic) mercury can evaporate to become an invisible, odorless toxic vapor. The warmer the air, the more quickly mercury vaporizes. Exposure to even a small amount can affect your health. Symptoms can surface within hours of exposure. According to the Centers for Disease Control and Prevention (CDC), exposure to mercury can result in short-term symptoms (e.g., coughing, vomiting) and long-term symptoms (e.g., loss of appetite, memory loss).

The problem with mercury is that it keeps on recycling itself. It vaporizes, is absorbed by materials in the environment (e.g., carpet, cloth, wood, window fixings), and again vaporizes into the air. This means that mercury drops can continue to turn into vapors that are breathed in by students and teachers years after a spill. It keeps recycling unless there is an intervention.

To determine if there is mercury in the lab, either secure a mercury detection kit or have a commercial lab test the science lab for mercury. If the results come back positive, the school district will need to hire a mercury spill clean-up contractor. If there is a small spill from, say, a broken mercury thermometer, see “How to handle a mercury spill” below.

Where can mercury be found in schools?

For decades, science teachers have used mercury in demonstrations and lab experiments involving oxygen production, exceptionally strong cohesive forces, and more. Before the health concerns about elemental mercury were evident, it could be found in a number of sites at schools, especially in science labs (e.g., glass thermometers, pressure gauges, batteries). Beyond the science lab, mercury can be found in fluorescent lamps and light bulbs, thermostats, switches, latex paint (produced prior to 1992), old microwave ovens, high-intensity discharge lamps, and silent, mercury-tiltwall switches.

All mercury instrumentation and mercury compounds need to be removed from labs appropriately. There are mercury thermometer exchange programs at the local and state levels, commercial hazardous waste vendors, and science laboratory equipment/supply houses.

Alternatives to mercury

Alcohol or electronic thermometers should replace all mercury-filled thermometers. There are also accurate alternatives to mercury barometers, vacuum gauges, manometers, and sphygmomanometers (blood pressure gauges) that rely on electronic or digital gauges and aneroid gauges. Other less hazardous chemicals such as a copper catalyst or zinc formalin can be in place of mercury for science demonstrations and experiments.

How to handle a mercury spill

Should there be a mercury spill, its size will dictate the response. Prepare for a spill by determining the mercury cleanup protocol from your school’s administration or board of education. In addition, general mercury spill guidelines are available from numerous sources, including most state departments of environmental protection and the Environmental Protection Agency. The EPA’s guidelines provide information on cleaning up mercury spills, including what never to do after a spill, preparation for cleaning up a broken mercury thermometer, materials for cleaning up the spill, and specific instructions for cleaning up a spill.

Submit questions regarding safety in K–12 to Ken Roy at safesci@sbcglobal.net or leave him a comment below. Follow Ken Roy on Twitter: @drroysafersci.

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