Fluorescent bulbs are a common staple of commercial buildings like big box stores, but you can also buy fluorescent bulbs for your home. Although these bulbs use less energy than traditional light bulbs, they also contain some dangerous chemicals. This means that you can’t just throw them in the trash — in some states, it's actually illegal! Instead, due to the way fluorescent bulbs are made, you need to find a place to properly dispose of them.
What Are Fluorescent Bulbs?
Fluorescent bulbs were originally designed as an energy-efficient alternative to traditional light bulbs.
Thomas Edison first patented the incandescent light bulb in 1879. For a long time, this was the standard household light bulb. Incandescent light bulbs are made of glass with a metal socket and wires inside. When electricity flows through these wires, the thin filament between the wires starts to glow and produce heat.
Unfortunately, incandescent light bulbs aren’t very energy efficient. They only turn about 10% of the energy they receive into visible light, and the rest they give off as heat. Today, many countries are looking to phase out incandescent light bulbs, including the U.S.
Edison was far from the only person working on lighting in the 19th century. Two Germans — a physician named Julius Plücker and a glassblower named Heinrich Geissler — discovered that if they removed nearly all the air from a glass tube and sent an electrical current through it, they could produce light. This was a type of low-gas discharge lamp that went on to inspire many other types of lights, like neon lights and fluorescent lights.
These sorts of lights weren’t taken seriously until the early 1900s, when researchers began to look for a more energy-efficient alternative to incandescent lights. Out of necessity, the U.S. rapidly adopted fluorescent lights during the Second World War because of an energy shortage. At this time, fluorescent lights were used commercially, like in factories, but were not available for residential use.
The 1973 oil crisis led engineers to develop residential fluorescent lights. These compact fluorescent lights, or CFLs, had a spiral-shaped tube. At the time, the cost of producing these CFLs was too high. When they finally did hit the shelves in the mid-1980s, they were too expensive for most consumers. Thanks to improvements over the years, CFLs are now much more affordable. They also use 75% less energy and last about 10 times longer than traditional incandescent bulbs.
Types of Fluorescent Bulbs
There are three primary categories of fluorescent bulbs: hot cathode, cold cathode, and electroluminescent.
Hot cathode lights. Hot cathode fluorescent bulbs are the most common type of fluorescent bulb. Fluorescent bulbs for household use, like CFLs, are hot cathode bulbs.
Hot cathode bulbs are made of glass tubes coated inside with phosphor, a material that releases light when exposed to radiation. Inside the tube is an inert gas (usually argon), which is a gas that doesn’t usually react with other substances. There is also a small amount of mercury gas in the tube. On either side of the tube is a tungsten electrode. The light is connected to a ballast, a device that monitors how much electricity is flowing through the light.
The electric current passes through the inert gas from electrode to electrode. When the electrons come into contact with the mercury atoms, the mercury atoms get excited, and ultraviolet light is released. But humans can’t see ultraviolet light, which is why the inside of the glass tube is coated with phosphor. When the ultraviolet light hits the phosphor, it releases light that you can see. This light is usually white, but manufacturers can change the color by using different types of phosphor.
Cold cathode lights. Overall, cold cathode lights work almost the same way as hot cathode lights. The main difference is how the electrons get into the tube.
Normally, you wouldn’t be able to send an electric current through gas. In order for this to work, the gas has to be ionized, meaning the atoms have a charge. In a hot cathode bulb, the gas inside the tub is ionized when a filament inside one of these electrodes heats up and boils electrons into the tube. In a cold cathode bulb, this is done by sending a much higher voltage between the two electrodes.
Cold cathode lights have a longer life but use more energy than hot cathode lights. These types of lamps are usually used in LCD screens.
Electroluminescent lights. Electroluminescent lights also use phosphors, but no gas. Instead, an electric current is sent straight through the phosphor. These lights can be made very flat and small, have a long life, and don’t use much energy, but they don’t emit much light. As a result, these types of lights are usually used for night lights, computers, and backlights on devices like watches.
Are Fluorescent Lights Bad for the Environment?
The dangerous thing about most fluorescent lights, including CFLs, is that they contain mercury. Mercury is found naturally in the environment from events like volcanic eruptions or forest fires, but most of the mercury in our ecosystem comes from humans. Burning fossil fuels is the largest contributor to mercury in the air. Power plants that burn coal are the biggest culprits and account for 44% of all manmade mercury emissions.
When mercury gets into the air, it eventually settles on the ground and in water. This can have massive ecological effects, especially on fish, birds and mammals that eat fish, and predators that eat those animals. Eventually, that mercury can make its way into humans.
Are Fluorescent Bulbs Hazardous Waste?
Generally speaking, fluorescent bulbs are considered hazardous waste due to the mercury inside of them. Some products may be labeled “low mercury” or “green” and are not considered hazardous but may still have mercury inside of them.
Mercury is a neurotoxin, meaning it affects nerve tissue. High levels of mercury exposure can cause problems with your brain, heart, immune system, kidneys, and lungs.
If you accidentally break a fluorescent bulb, you need to be very careful cleaning it up. The U.S. Environmental Protection Agency provides instructions for cleaning up broken CFL bulbs, including:
- Evacuate the room
- Open a window or door and let the room air out for 5–10 minutes
- Shut off central forced air systems if you have them
- Use stiff paper or cardboard to clean up large pieces and sticky tape for small pieces
- Place all used items in a sealable container, and keep it out of reach until you can bring it to the proper facility
Can You Recycle Fluorescent Bulbs?
You can and should recycle fluorescent bulbs. In fact, some states may prohibit you from throwing mercury-containing bulbs into the garbage. When you bring these items to the proper facility, it prevents the mercury from being released into the environment. Additionally, many parts of the bulb, like the glass and metal, can be recycled into something new.
How to Recycle Fluorescent Bulbs
There are several ways you can recycle your fluorescent bulbs. The easiest way is to go to search.earth911.com to find recycling locations and collection services near you. You can also check with your local waste collection agencies and retailers, especially hardware stores. Some bulb manufacturers will even provide you with a mail-in kit so you can send your used or broken bulb back.
If there are no services near you and your state allows you to throw fluorescent lamps away, seal the bulb in a plastic bag so that if the bulb breaks, the mercury is contained.