TL;DR
Mercury still sits inside old thermostats, fever thermometers, tilt switches, float switches, and every fluorescent tube in the house. If one breaks, do not vacuum it, and do not sweep it.
Mercury is a liquid metal that evaporates at room temperature, which is the whole problem. The vapor is what you breathe, and a vacuum turns a small spill into a room full of it.
Where Mercury Actually Hides
Most homes built or updated before the mid 2000s hold at least one mercury device. It is rarely labeled, and it is usually inside something you would never think twice about.
| Item | Where the mercury is |
|---|---|
| Round dial wall thermostat | A sealed glass ampoule on a tilting coil |
| Fever thermometer | The silver column in the glass stem |
| Fluorescent tube or CFL | A tiny vapor dose inside the tube |
| Chest freezer light switch | A tilt switch in the lid frame |
| Sump pump float switch | A sealed tilt bulb in the float |
| Gas appliance flame sensor | A mercury flame sensor in older units |
| Older barometers and manometers | A visible mercury column |
| Some button cell batteries | Legacy mercury oxide chemistry |
The two that turn up most often in cleanouts are the round dial thermostat behind a newer smart unit that nobody ever removed from the wall, and a box of old fluorescent tubes in a garage rafter.
How Much Is in There
A single fluorescent tube holds a very small amount, measured in milligrams. A dial thermostat holds a few grams, which is thousands of times more. An old fever thermometer sits in between.
This matters because the response scales with the amount. A broken CFL is a cleanup you can do carefully in ten minutes with the window open. A broken thermostat ampoule that puts visible beads of mercury on a carpet is a different situation, and carpet is genuinely difficult to decontaminate.
Nothing here is a reason to panic. It is a reason to handle these items deliberately instead of tossing them in a bag with everything else, which is the same logic behind what qualifies as hazardous waste.
Never Vacuum, Never Sweep, Never Pour
Three actions turn a contained spill into a spread one.
A vacuum heats the mercury at the motor and blows fine vapor and droplets throughout the room, and the vacuum itself becomes contaminated waste. A broom shatters the beads into smaller droplets that scatter into flooring seams and increase the surface area evaporating into the air. Washing it down a drain puts mercury into the sewer system and leaves residue in the trap.
Also skip the shop vac, the carpet cleaner, and the laundry machine. Clothing or bedding with visible mercury on it should be bagged, not washed.
How to Contain a Small Break
Get people and pets out of the room first, then open exterior windows and leave the room closed off from the rest of the house for a few hours. Turn off forced-air heating or cooling so the system does not distribute vapor.
Put on disposable gloves. Pick up glass pieces with stiff cardboard and place them in a sealable glass jar or a zip bag inside a second bag. Push scattered beads together with the cardboard, then lift them with an eyedropper or press them up with the sticky side of tape.
Light the area from a low angle with a flashlight to find the beads you missed, because they reflect and are easy to spot that way. Put every used glove, card, and tape strip in the same sealed container, label it plainly, and take it to a hazardous waste drop-off.
Keep the room ventilated for a day afterward if you can.
Where to Take Mercury Items
Mercury devices go to household hazardous waste collection, not the trash and not curbside recycling. Most county transfer stations run a household hazardous waste day, and larger metro areas operate year-round depots. Check your county's solid waste page for hours, quantity limits, and whether they accept items from businesses.
In the Portland area, Metro South Transfer Station in Oregon City and Metro Central Transfer Station in northwest Portland both accept residential household hazardous waste within posted limits. Elsewhere in the state, the household hazardous waste intake is usually at the transfer station co-located with the regional landfill rather than at the landfill face itself.
Some heating and cooling contractors participate in thermostat takeback programs when they replace a unit. Terms vary by contractor and change over time, so ask at the time of the job rather than assuming.
What Not to Confuse With Mercury
Not every silver thing in an old house is mercury. Aluminum tape, solder, and the silvered backing on an old mirror are not. A digital thermometer with a battery is not, and neither is a modern spirit thermometer, which uses a dyed alcohol column and is usually red or blue.
Smoke detectors are a common false alarm in the other direction. Ionization detectors contain a tiny sealed radioactive source, not mercury, and they have their own disposal path covered in smoke detectors.
If you cannot tell, treat the item as suspect and route it to hazardous waste. It costs nothing extra to be wrong in that direction.
FAQ
How do I know if my old thermostat has mercury in it?
Pull the cover off and look for a small sealed glass tube with a visible silver bead inside, usually mounted on a coiled bimetal strip. Round dial thermostats made before the mid 2000s commonly have one. Programmable digital units and modern smart thermostats do not. Handling is covered in mercury thermostats.
Is it safe to be in a room where a thermometer broke?
Leave and ventilate first, then clean up carefully. Brief exposure to a small break is not the same as ongoing exposure, and the health concern is mainly about breathing vapor over time in an unventilated space. Do not sleep in the room until it has aired out and the beads are gone.
Can I throw a burned-out fluorescent tube in the trash?
You should not. Tubes break in the truck and release their mercury, and many states ban them from solid waste outright. Hardware stores and county programs commonly take them, and the practical options are covered in fluorescent bulbs and tubes.
What do I do with mercury I collected in a jar?
Seal it, label it clearly as mercury, keep it upright, and store it somewhere cool and out of reach until you can get it to a hazardous waste drop-off. Do not transport it loose in a car cabin. Put the sealed container in a box in the trunk.
Do junk removal crews take mercury items?
Usually not on a standard truck, because hazardous materials require separate handling and permits. Set those items aside, tell the crew they exist so nothing gets loaded by accident, and deliver them to a county program yourself.
Clearing Out the Rest
Once the mercury items are set aside, the rest of an old basement, garage, or estate cleanout is straightforward volume work. Junk removal is the next step for the rest while you handle the small hazardous pile separately. Mention what you found when you get a quote and we will tell you exactly what we can and cannot load.
