The Small Mercury Spill SOP

Purpose

When a thermostat bulb, a float switch or a thermometer breaks on a job, the first ten minutes decide whether the mercury ends up sealed in a jar or spread through a house as vapor. Instinct reaches for a vacuum, a broom or a paper towel, and every one makes the room worse. This SOP fixes the order, following the household cleanup method EPA publishes for a broken thermometer: clear the room, ventilate, size the spill against a hard limit, collect without breaking beads up, seal and label, and tell the customer honestly what was done.

Scope

Covers: a spill of elemental mercury no larger than the contents of one thermostat bulb, one fever thermometer or one tilt switch, on a hard floor, a countertop, a truck bed liner or a short-pile rug, in a customer's home or in the shop.

Does not cover: anything larger, mercury in deep carpet or a duct, a spill on a heat source, or one with a child or pregnant person in the room (all stop at step 3 and are referred out); a gas regulator leaking mercury at a meter (utility property, call the utility); handling intact devices (see related: Mercury Thermostats, Switches and Gauges); and disposal past the shop's waste area (see related: Setting Up a Segregated Waste Area at the Shop).

Roles and responsibilities

The handoff that fails is tech to office: a tech who calls it "basically cleaned up" and drives on leaves no record and no referral.

Procedure

1. Clear the room and close it off

Stop work. Get everyone, pets included, out of the room without crossing the spill, and close the doors between the room and the rest of the house. Leave your tools where they lie. Acceptance: nobody in the room but you, doors closed, nobody has walked across the area. Wrong looks like: a child or dog already tracking through, someone fetching a vacuum. Stop rule: anyone who walked through it leaves their shoes at the door for bagging at step 8. If a vacuum has already been run over it, leave the vacuum unplugged in the room and go to step 3's referral. Hazard: vapor inhalation, and beads carried through the house on soles; you stay off the spot too.

2. Ventilate to the outdoors and shut off forced air

Open every window and exterior door in the room. Turn the HVAC system off so forced air does not carry vapor through the ducts, and turn off any space heater, because mercury evaporates faster as it warms. Wait at least 15 minutes outside the room before collecting. Acceptance: windows open, air handler off, at least 15 minutes elapsed by the clock. Wrong looks like: a room with no exterior window, or a broken bulb that is lying on a warm surface such as a furnace cabinet or a sunny sill. Stop rule: a room with no way to ventilate outdoors, or mercury on a hot surface, goes to step 3's referral. Hazard: the shutoff happens at a switch you can reach without crossing the spill; never step over it to reach a thermostat.

3. Size the spill against the limit and decide

From the edge, hold a flashlight low to the floor so the beads catch the light. Acceptance: total mercury no more than one bulb or one thermometer's worth, all of it on a hard or short-pile surface, nothing in a floor register or duct, nobody in the room who is pregnant or a young child. Wrong looks like: beads spread across more than about a square yard, beads in a register, a pool from a broken manometer or barometer, mercury worked into thick carpet. Stop rule: any one of those and you stop collecting, keep the room closed and ventilating, and call the office, who calls the local health department or poison control for direction. Federally, a release of a pound or more of mercury, roughly two tablespoons, is a reportable quantity under CERCLA and goes to the National Response Center; you will never reach that from a thermostat, but a broken manometer can. Hazard: the inspection is done from the edge; you do not kneel in the area to look.

4. Dress for it, and strip what mercury attacks

Remove rings, watches and bracelets (gold and silver amalgamate with mercury), then put on nitrile or rubber gloves and bags over your boots. Acceptance: no metal on hands or wrists, gloves on, footwear covered. Wrong looks like: cloth gloves, which soak droplets up. Stop rule: no nitrile gloves in the van means stop and get them before touching anything. Hazard: the inhalation route is controlled here by ventilation time and short work duration, not by a respirator; a respirator is used only by a tech in the shop's OSHA 29 CFR 1910.134 program with cartridges rated for mercury vapor, and a shop without that program does not extend this work beyond the small-spill limit to make up for it.

5. Collect the glass first

Pick up broken glass and the rest of the device slowly by hand, lay them on a damp paper towel, fold it over and put it in a wide-mouth jar with a screw lid or a heavy zip bag. Acceptance: no glass visible under the low flashlight. Wrong looks like: shards hidden under beads, or glass picked up with a brush. Stop rule: a cut through the glove means stop, wash it with soap and water, and swap gloves. Hazard: thin capsule glass; lift shards by the edges, never press down on them.

6. Gather the beads without breaking them

Use two stiff cards or pieces of cardstock to push beads slowly toward each other until they merge into larger ones, then roll them onto one card and tip them into the jar. An eyedropper picks up beads too small to push. Work from the outside of the spill inward. Acceptance: flashlight sweeps from three different low angles show no glints. Wrong looks like: beads splitting into smaller ones as you push, beads rolling into a floor seam, a gap at a baseboard or a heat register. Stop rule: a bead in a seam or a gap stays there; never pry or dig with a screwdriver, which turns one bead into many. Mark its position with tape beside it, not on it, and record it for step 9. Hazard: keep your face above and away from the beads, and do not hold the jar open longer than it takes to tip a card in.

7. Lift what the cards missed with tape

Press wide packing or duct tape firmly over the area to lift droplets too small to see, fold it sticky side in, and drop it in the jar. Repeat until a fresh piece comes up clean under the flashlight. Acceptance: two consecutive tape lifts with no visible silver on them. Wrong looks like: tape lifting carpet fibers full of droplets, which means the mercury is in the pile, not on it. Stop rule: droplets in carpet pile go back to step 3's referral; the shop does not cut a customer's carpet, which is the homeowner's decision with the health department's advice. Hazard: contact on the glove surface; change gloves if you see silver on them.

8. Seal, label and move it out of the house

Cards, tape, eyedropper, towels, gloves and any shoes or covers go into the jar or a second bag; close it, tape the lid, label it, and carry it outside. Acceptance: closed container, taped lid, label filled in, stored outside the living space and the cab. Wrong looks like: an open bag in the cab, an unlabeled jar on a counter. Stop rule: no lidded container on the truck means two heavy zip bags inside a rigid box, never one thin bag. Hazard: a cab in the sun is a heated enclosed space; mercury debris rides in the cargo area, upright, wedged so it cannot tip.

  +----------------------------------------------+
  |  MERCURY SPILL DEBRIS - DO NOT OPEN          |
  |  Contents: glass, beads, cards, tape, gloves |
  |  Source:   thermostat bulb (1 of 2)          |
  |  Address:  [job address]   Job no: [number]  |
  |  Date:     [date]   Tech: [initials]         |
  |  Beads left in place: 1, hall floor seam     |
  |  Route:    shop waste area -> HHW / recycler |
  +----------------------------------------------+

9. Close out the room and brief the customer

Ask for the windows open, door closed and HVAC off for at least 24 hours. Tell the customer what broke, how much, what was collected, whether anything was left in place, and who can check the air (the local health department, which in many areas screens with a mercury vapor meter). Wipe your boot soles with a damp towel and bag it before getting in the van. Acceptance: customer told all five things, and either agrees to the 24-hour ventilation or has said no and that is recorded. Wrong looks like: "it's fine, we got it all" when a bead was left in a seam. Stop rule: a customer who refuses ventilation, or one who is pregnant or has young children living in the room, gets the health department referral from the office the same day, whatever the size. Hazard: restarting the HVAC early carries any remaining vapor through the house; tell the customer that is the reason, not just the rule.

The record this produces

An incident entry on the job, started by the tech before leaving and completed by the office: time of the break, device and estimated amount, surface, who was in the room, when ventilation and collection began, the step 3 decision, anything left in place and where, what the customer was told, any referral and to whom, and where the sealed container went. The owner reads it within one working day. If the customer later reports symptoms or a vapor reading, this timed, on-site entry is the shop's account of what it did.

Worked pass

A tech is replacing a dial thermostat in a hallway with oak strip flooring. Lifting the body off the subbase, one of its two bulbs catches the wall plate and cracks; a bead about the size of a lentil drops and splits on the floor.

• Step 1: Dog kept in the kitchen, hall doors closed at both ends, nobody walked through. Passed.
• Step 2: Two bedroom windows opened, furnace off at the old thermostat's switch (reachable without crossing the floor), 15 minutes timed outside. Passed.
• Step 3: One bulb's worth on hard flooring, the register two meters away untouched, no children in the home. Within the limit; office called. Passed.
• Step 4: Ring off, nitrile gloves on, bags over boots. Passed.
• Step 5: Two pieces of capsule glass onto a damp towel, into a lidded jar. Passed.
• Step 6: Cards gather about a dozen droplets into three beads, all tipped in. The third flashlight sweep, from the baseboard side, shows one glint down in the seam between two floor strips. Failed. Stop rule applied: no prying; a strip of tape placed beside the seam marks the spot, and the bead is logged as left in place.
• Step 7: Two tape lifts come up clean. Passed.
• Step 8: Tape, cards, gloves and boot bags into the jar, lid taped, label filled in with "Beads left in place: 1, hall floor seam", jar wedged upright in the cargo area. Passed.
• Step 9: The customer is told: one bulb broke, about a lentil's worth, collected except one bead in the floor seam, windows open and furnace off for 24 hours, and the health department number for an air check. The customer agrees to the ventilation. Because a bead remains, the office places the health department referral the same afternoon and notes it on the job.

The step 6 failure took its stop rule rather than a screwdriver, and the bead left in place shows up in the label, the briefing and the referral, the three places the next person will look.

References

• EPA, "What to do if a mercury thermometer breaks" and the related household mercury spill cleanup pages
• OSHA, 29 CFR 1910.134 (respiratory protection programs)
• EPA, CERCLA reportable quantity for mercury (one pound) and the National Response Center
• Your local health department or poison control center for spill referral and vapor screening
• See related: Mercury Thermostats, Switches and Gauges; Setting Up a Segregated Waste Area at the Shop