Yael: Hey Don, do you know that many communities offer medical thermometer      exchange programs, and will replace your old mercury-filled thermometer with a      safer non-mercury one free of charge?

Don: Are mercury thermometers really so dangerous, Yael? Isn't the mercury safely      sealed inside glass?

Y: While mercury thermometers are safe when used correctly they pose significant risks      when they break or if disposed of improperly. Mercury is a highly toxic metal and      excessive exposure can cause serious health problems including neurological      disorders.

D: How do the new safer thermometers work?

Y: There are several types of accurate non-mercury thermometers for home use. Spirit      thermometers use a non-toxic alcohol --usually dyed red or blue -- instead of      mercury to register the temperature. Like liquid mercury, the alcohol expands in      volume as it gets warmer, causing the liquid to move up the thin tube inside the glass      thermometer. Digital thermometers contain a device called a thermoresistor. The      thermoresistor has an electrical current running through it, and the resistance, or how      freely the current can flow, changes with temperature. A small computer or other      circuit measures the resistance and converts it to a temperature, which is then      displayed on the thermometer screen.

D: Pretty neat. How do people find out about thermometer-exchange programs in their      area?

Y: They could try calling their local health department or pharmacy to ask about      programs in their area. But, even if their community doesn't offer an exchange      program, it is important to properly dispose of mercury-containing products.      Mercury should never go in the regular household trash. Contact your local      hazardous materials department to learn the right way to protect you and your      environment from mercury contamination.  

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