Are Mercury Thermostats Safe?

Lawrence Bonk
Written by Lawrence Bonk
Updated December 17, 2021
A working vintage thermostat containing mercury
Photo: Justin / Adobe Stock

Mercury should be rotating the sun, not hanging out in your thermostat

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Ah, the good ol’ days. Playing in the snow with friends. Staying home from school when you get the sniffles, with parents shoving mercury thermometers in your mouth. Wait a minute— those weren’t good ol’ days at all. Mercury is a hazardous chemical element that shouldn’t be anywhere near the human mouth. Mercury exposure leads to serious health ailments, including the dreaded mercury poisoning. That’s why modern consumers switched over to digital thermometers many moons ago. 

So, if mercury is bad for thermometers, are mercury thermostats safe? Short answer, heck no. Kick them to the curb. Here’s why.

Dangers of Mercury in Thermostats

Mercury thermostats are, essentially, hazardous waste containers hanging out on your wall. They pose all sorts of dangers for human health, animal health, and the health of the planet. And if you accidentally break your thermometer, you'll have to clean up the mercury spill safely and quickly.

Health Dangers of Mercury Thermostats 

Exposure to water-soluble forms of mercury, inhalation of mercury vapor, or eating food contaminated with mercury leads to mercury poisoning. At high levels, mercury exposure causes brain damage, heart failure, kidney damage, lung issues, and severely hampers the immune system. Even worse? These risks are greater for children and, especially, infants. A study released by the National Center for Biotechnical Information suggested mercury poisoning even impacts infants in the womb due to their underdeveloped immune systems. 

In most cases, the mercury in a thermostat stays locked away behind glass, but accidents happen. If your thermostat breaks, releasing mercury, contact the EPA’s National Response Center.

Environmental Dangers of Mercury Thermostats

Even though most of the environmental contamination from mercury comes from large-scale industrial use, the quicksilver form of mercury found in thermostats poses a real danger to the planet. Mercury-containing thermostats transform into hazardous waste if improperly disposed of, leading to air contamination, ground surface contamination, and groundwater contamination. Wild animals react to mercury in much the same ways we do. In other words, exposure leads to poisoning.  

How to Check if You Have a Mercury Thermostat?

Hands removing a mercury thermostat cover
Photo: spatesphoto / Adobe Stock

If your thermostat hails from any time before 2005, it likely contains mercury. After that date, digital thermostats entered the stage, eventually gobbling up the thermostat market share. However, modern companies still make mercury thermostats despite regulations in multiple states regarding the sale of the chemical. A good rule of thumb? If your thermostat features an analog dial or lever, it probably includes two to six grams of mercury. 

Check to see if your thermostat contains mercury by removing the front plate. Do you see one or more small glass bulbs inside? These bulbs are tilt switches, and each one fills with up to six grams of mercury.

Alternatives to Mercury Thermostats 

Don’t worry. You won’t find yourself in the (literal) cold by dumping your mercury thermostat. Choosing a thermostat that works for your lifestyle is easy. There are plenty of different types of thermostats to choose from—all of which do not pose health dangers or environmental risks. 

Standard Digital Thermostats

This is the cheapest option, a standard non-programmable digital thermostat. In other words, it just reads and displays the thermostat temperature. There is no mercury here, but neither are there any bells and whistles. These are as bare-bones as you get. 

Programmable Digital Thermostats 

Programmable digital thermostats are great for the budget-conscious, as standard models are economical, and you get an extra savings boost by programming or setting it correctly. The U.S. Department of Energy says that you’ll save up to 10% yearly just from having your thermostat set to seven to 10 degrees above your average temperature in the summer or below your average temperature in the winter. 

Wi-Fi and Smart Thermostats 

These are the newest and most fabulous thermostats on the market. They allow temperature adjustments via a smartphone app and integrate with AI smart assistants, like Amazon’s Alexa. High-end models include touchscreens, battery backups, robust vacation modes, and more. Many also feature geofencing capabilities, meaning the thermostat automatically adjusts the temperature as you’re on your way home. Pretty nifty. 

What to Do With Old Mercury Thermostats?

Once you’ve switched to a modern digital thermostat, what should you do with the old mercury-based model? Many states highly regulate mercury disposal. Never throw away a mercury thermostat; other disposal options exist. 

Thermostat Recycling 

Contact a local regulatory agency to learn the proper way to recycle a mercury thermostat. Some cities, states, and municipalities set up bins to place mercury thermostats, while others organize yearly recycling events. Many nonprofit and for-profit organizations specialize in recycling mercury thermostats. Perform a quick web search and give one of these entities a call or email. 

Pros Handle It 

If you hire a local electrician to replace your thermostat, ask them to take the old one on the way out. Many companies are happy to do so at no additional fee and, due to their experience with mercury thermostats, they’ll know exactly how to dispose of it properly. 

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