Older glass thermometers often contain elemental mercury, typically \(0.5\) to \(2\) grams of this silvery liquid metal. If the glass tube breaks, the mercury disperses into tiny droplets. These droplets can vaporize into an invisible, odorless gas at room temperature. This vapor is the primary health hazard because it can be inhaled and absorbed through the lungs, which is particularly concerning in enclosed spaces or by sensitive populations like children. Immediate, careful action is necessary to contain the spill and minimize the risk of exposure.
Immediate Safety Measures and Area Preparation
The first response when a thermometer breaks is to ensure the safety of all occupants. Immediately evacuate all people and pets from the room to an uncontaminated area. Prevent anyone from walking through the spill, as mercury droplets adhere easily to shoes and clothing, spreading contamination throughout the dwelling.
Establish proper ventilation immediately to reduce the concentration of mercury vapor. Open windows and exterior doors in the affected room, but close all interior doors to contain fumes. Turn off central heating, air conditioning, and fans to minimize air circulation that might disperse the vapor.
Before cleanup, wear non-porous gloves, such as nitrile or latex, to prevent direct skin contact. Although direct contact is less hazardous than inhalation, prolonged exposure can cause irritation. Consider wearing old clothes or plastic shoe covers that can be safely discarded after the cleanup is finished.
Avoid certain cleanup methods that will worsen the situation. Never use a vacuum cleaner, as the motor’s heat increases vaporization, and the exhaust blows mercury vapor and particles into the air. Do not use a broom or a mop, as these tools break the liquid metal into smaller, harder-to-collect beads and spread contamination.
Detailed Steps for Collecting Mercury Droplets
Once the area is isolated and you are protected, begin locating and collecting the scattered mercury droplets. First, carefully pick up any broken glass pieces using stiff paper or cardboard, place the shards onto a paper towel, and set them aside for disposal.
To locate the nearly invisible droplets, use a flashlight or task light held at a low angle close to the floor in a slightly darkened room. This technique makes the mercury beads glisten and reflect light, revealing their location, even in small cracks or crevices. Inspect the entire room thoroughly, as mercury moves easily on smooth surfaces.
The main collection method uses two pieces of stiff paper or thin cardboard to gently push the beads together. Elemental mercury has high surface tension, causing smaller droplets to merge into larger, manageable balls when pushed slowly. Work slowly and carefully to prevent the droplets from scattering further.
Use an eyedropper or plastic pipette to collect the combined mercury beads. Suck up the liquid, then carefully squeeze the collected mercury onto a damp paper towel. Repeat this process until all visible large beads have been collected from the surface.
After the larger beads are removed, any remaining microscopic fragments or powder can be picked up using a piece of sticky material, such as duct tape or masking tape. Gently “dot” the affected surface with the adhesive side of the tape to lift the remaining residue. Alternatively, a small paintbrush with shaving cream can be used to gently dot the area for the same purpose. If the mercury spilled onto absorbent surfaces like carpet, rugs, or upholstery, those materials cannot be effectively cleaned. The contaminated portion must be carefully cut out and removed for disposal along with the collected mercury waste.
Safe Disposal Procedures and Next Steps
Once collection is complete, all contaminated materials must be secured in an airtight container to prevent further vaporization. Use a sturdy, sealable plastic bag or a glass jar with a tight-fitting lid.
The materials to be sealed include:
- The paper towel with the collected mercury
- The eyedropper and cardboard
- The duct tape and gloves
- The broken glass pieces
Place the sealed container inside a second, thicker plastic bag for protection, and clearly label the entire package as “Hazardous Waste—Contains Mercury.” This prevents accidental exposure and informs waste handlers. Store the sealed waste in a secure, non-living space, such as a shed or garage, until proper disposal.
Never place the sealed mercury waste into household trash, pour it down a drain, or dispose of it outside an approved hazardous waste program. Mercury is classified as household hazardous waste, and improper disposal contaminates water and soil. Contact your local municipal waste authority or health department for specific disposal instructions.
These local authorities can direct you to a household hazardous waste (HHW) collection facility or inform you about scheduled collection events. After cleanup, the room should remain well-ventilated for at least 24 hours to ensure residual mercury vapor disperses. If a large amount of mercury was spilled or absorbent materials were extensively contaminated, contacting a professional hazardous waste remediation service is advisable.