Somewhere in every hotel, restaurant, and older office building in Miami-Dade there is at least one exit sign with a small green glow that never dims — no batteries, no wiring to the ceiling grid, no visible power source. If you've never noticed it, that's the point. Self-luminous exit signs are engineered to be forgettable, which is why so many of them get thrown in the dumpster during a remodel by someone who has no idea they contain a radioactive gas.
They do. Tritium — hydrogen-3, a low-energy beta emitter — sealed inside phosphor-coated glass tubes. And "throw it in the dumpster" is not among the legal disposal options.
What a self-luminous exit sign actually is
A tritium exit sign contains between about 5 and 20 curies of tritium gas, held in sealed borosilicate tubes coated on the inside with a phosphor. The tritium's beta decay excites the phosphor, producing steady light for 10 to 20 years — the tubes dim as the tritium decays, with a 12.3-year half-life. No electricity, no maintenance, guaranteed illumination during a power outage. That's why they got installed by the tens of thousands in South Florida properties starting in the 1980s.
The catch: the sealed tubes are not designed to be user-serviceable, and the sign as a whole is regulated as a generally licensed radioactive device under 10 CFR Part 31 by the U.S. Nuclear Regulatory Commission — or, in Miami's case, by the State of Florida under its Agreement State authority.
The general license nobody remembers signing
When your property acquired a tritium exit sign, it acquired an NRC general license along with it. You did not have to apply, and you probably did not receive documentation you'd recognize as a radioactive materials license. The obligations, however, are real. In summary:
- You must not abandon, dispose of in ordinary trash, or damage the sign.
- You must report any loss, theft, or damage to the NRC (or your Agreement State agency).
- You must transfer the sign only to a person authorized to receive it — typically the original manufacturer, another licensed distributor, or a specialty radioactive waste broker.
- You must maintain records of receipt, transfer, and disposal, and provide them to inspectors on request.
In practice, most Miami property managers we talk to have never seen the general license. The information is on a label on the back of the sign, and it's usually facing the wall.
Your realistic disposal options
Three legitimate routes exist:
1. Return to the original manufacturer.
Isolite, SRB, Shield Source, and the other historical U.S. manufacturers all operate return programs. There is a fee — usually in the range of $75 to $250 per sign depending on curies and shipping — but the paperwork is minimal, and the manufacturer files the disposition record. If the manufacturer has gone out of business (which has happened to several), you fall back to option two.
2. Ship to a licensed radioactive waste broker.
A specialty broker will accept tritium exit signs, aggregate them, and forward them to a licensed low-level radioactive waste disposal facility. Per-sign pricing is generally similar to manufacturer returns. Regional hazardous waste contractors that handle universal waste and radioactive streams will often coordinate this on your behalf. If you're looking at bulk exit-sign disposal in Miami — say, a hotel taking out sixty signs in a lobby refit — hazardous waste disposal in Miami, FL providers can handle the pickup, packaging, and manifest under an existing radioactive materials license so you don't have to open one yourself.
3. Local landfill acceptance — occasionally, for intact signs at very low activity.
Some states have provisions for exit signs below a certain curie threshold to go to landfill under specific conditions. Florida is not one of them for practical purposes. Do not rely on this route in Miami-Dade or Broward.
What to do with a broken sign
A cracked tube is the scenario people worry about most, and understandable so. Tritium is a beta emitter — the radiation is easily stopped by a sheet of paper or the outer casing of the sign, so external exposure from an intact sign is negligible. The concern with a broken tube is inhalation or ingestion of tritium as tritiated water vapor.
If a sign is cracked:
- Ventilate the area immediately. Open doors and windows. If it's an interior corridor, run the HVAC on 100% outside air if possible.
- Do not vacuum. Do not use a wet mop. Both spread contamination.
- Isolate the sign in a sealable plastic bag or bucket with the lid loose (never pressurized).
- Contact the manufacturer or a licensed broker for guidance on shipping and cleanup surveys.
- File the incident report with the state Bureau of Radiation Control within the required timeframe (typically 24 hours for reportable incidents).
Most "broken" signs we hear about were cracked when a maintenance worker pried the sign off the wall with a screwdriver, not from an impact. Removing tritium signs is a two-person job — one to hold, one to disconnect from the mounting bracket, no prying.
LED replacements: what to look for
The reason people are pulling out tritium signs in the first place is usually a lobby renovation, a code-driven upgrade, or a sign that has visibly dimmed past readability. The replacement standard is LED with a battery backup — either sealed lead-acid or lithium iron phosphate. When specifying replacements, look for signs that meet NFPA 101 Life Safety Code visibility requirements at 100 feet and have a 90-minute battery runtime under load. Most Miami-area electrical distributors carry code-compliant units in the $30–$80 range.
Just don't put the old signs in the same dumpster as the drywall.
Recordkeeping after disposal
Whatever route you take, keep the disposition record — the certificate from the manufacturer or broker showing that the sign was received and processed under their license — for the life of the building, or at minimum three years. It is the only defensible answer to the question "what did you do with that sign?" during an inspection or a property transfer.
For a single sign, this feels like overkill. For a hundred signs across a hotel portfolio, it is the difference between a routine records request and a very expensive Sunday afternoon.