Healthy Lightbulb Guide
The type of lightbulb that you use in your home can have an impact on your health and the environment. Electric lighting is one of the major sources of energy consumption which is why lightbulbs have received a great deal of regulatory focus to improve their efficiency. This regulation has led to a shift from incandescent bulbs, which are less efficient, to fluorescent and more recently, LED bulbs. However, there are several components and features of lightbulbs that impact human health that should be considered along with energy efficiency.
Types of Light Bulbs
Incandescent
Incandescent lightbulbs conduct a current through a filament that is heated until it glows. Most of the energy created is in the form of heat and only a small portion (<10%) is visible light which is why it is much less energy efficient than other types of lightbulbs. (source)
Incandescent bulbs have the fewest health risks and are the safest type of lightbulb.
Availability of incandescent bulbs has been sporadic because of their energy inefficiency. The Energy and Independence and Security Act of 2007 (EISA) required incandescent bulbs to be phased out over several years and replaced by higher efficiency bulbs. In 2019, the Trump administration rolled back the regulation. (source) There are now a small number of manufacturers still producing incandescent bulbs and some have improved their energy efficiency. Some states have adopted their own policies and California has maintained a ban despite the federal roll back, so availability may vary by state.
Incandescent bulbs are made with less toxic materials than other types of bulbs. The environmental impact of lightbulbs is typically measured based on energy consumption and does not consider the impact of hazardous materials. One study found that when these materials were taken into consideration, incandescent bulbs had a considerably lower impact than fluorescent and LED bulbs. (source)
Halogen
From a health perspective, halogen bulbs are like incandescent bulbs except low-voltage halogens (6 – 25 volts) can have high levels of electromagnetic radiation (EMR) because they require a transformer and high-voltage halogens (110 or 120 volts) can be a fire hazard because they generate high levels of heat.
Compact Fluorescent
Compact fluorescent lightbulbs (CFLs) were designed to replace incandescent lightbulbs because they use one-fifth to one-third the electrical power and can last fifteen times as long. (source) All fluorescent bulbs contain toxic mercury. Electrons that are bound to the mercury atoms are excited and radiate ultraviolet light. The UV light coverts to visible light when it strikes the fluorescent coating on the inside of the bulb. (source) It’s possible for some UV to escape if there are openings in the coating, creating an additional health risk. CFLs have the greatest health risks overall and are not recommended.
LEDs
A LED (light-emitting diode) is a semi-conductor light source that emits light when current flows through it. (source) They have much greater energy efficiency and lifespan than incandescent bulbs. Technology continues to improve but the quality of components and corresponding health effects vary among LED bulbs.
Health Impact of Different Lightbulb Types
Potential Health Impacts
Heavy Metals
All lightbulbs contain some heavy metals, but different types of lightbulbs have different hazardous exposures. Consumers can be exposed to these chemicals if a lightbulb breaks in the home, but there is risk to the environment and occupational workers throughout a product’s lifecycle.
Mercury
Mercury from lightbulbs is harmful to the environment. All fluorescent bulbs contain mercury and require special handling throughout their lifecycle. Many states categorize fluorescent lightbulbs as hazardous waste that require consumers to bring them to a special facility for recycling. Studies show that a very small percentage, with some studies showing as low as 2%, of these bulbs are recycled. (source) Mercury that is not properly disposed of can enter the water system and ultimately end up in the food chain. Mercury is considered a persistent bio-accumulative that never degrades in the environment. (source)
Consumers can be directly exposed to harmful levels of mercury if a lightbulb breaks and is not properly cleaned up. When a fluorescent bulb breaks in the home, vapors are released that can be inhaled or absorbed through the skin. One study found that the level of mercury exposure from a broken lightbulb on average exceeded the EPA’s safe or “reference” dose of mercury and in some instances significantly exceeded it. (source) The EPA has guidelines for proper clean-up of a broken fluorescent bulb that include immediate ventilation of the room.
Other Heavy Metals
All types of lightbulbs can contain some amount of lead and some contain antimony, arsenic, copper and other heavy metals. One study found that incandescent bulbs contained the lowest amount of most heavy metals tested. (source) Care should be taken when cleaning up all types of lightbulbs to avoid heavy metal exposure and proper recycling requirements should be followed.
Electromagnetic Radiation (EMR)
Building Biologists look at different types of EMR that can impact human health including electric and magnetic fields, radio frequencies and dirty electricity. There are many aspects associated with lighting in addition to lightbulb type that can generate EMR such as house wiring, wireless lighting controls and dimmers. The best way to minimize all forms of EMR from your lighting is to have a certified Electromagnetic Radiation Specialist (EMRS) test the levels within your home. In the absence of that, studies of EMR emitted from different types of bulbs provide general guidance. (source)
Incandescent bulbs are low in all EMR.
Low-voltage halogen bulbs can have high levels of dirty electricity and magnetic fields because they use a transformer to step down the voltage from the main to the bulb.
CFLs have high levels of dirty electricity. They can also have high levels of magnetic fields which could be a concern if the light source is within 1 ft. of a person, such as in a bedside lamp.
LEDs have varying levels of dirty electricity. It is difficult to know which ones are safe without testing, but higher quality bulbs are more likely to have lower levels.
Dimmers can also generate high levels of dirty electricity and are not recommended.
Emission Spectrum of Light
Natural sunlight follows a smooth and continuous distribution of wavelengths that we perceive as color. In the morning and evening there are higher levels of reds and yellows and at midday there are higher levels of blues, but the distribution remains smooth with all colors present at some level. Incandescent bulbs most closely mimic natural sunlight with a smooth distribution. Fluorescent bulbs follow a spikey pattern with high peaks of particular wavelengths and negligible levels of wavelengths in between. (source) The spiked wavelengths are thought to be more difficult for the eyes and brain to process. (source) The distribution in LED lights is variable but technology is improving, and new products are being developed with a smooth, continuous distribution. Nature is the gold standard and choosing lighting that most closely mimics natural sunlight is optimal.
Overexposure to blue light, particularly at night, has also been linked to numerous health effects such as eye damage, melatonin suppression and increased stress. (source) Fluorescent lights have high levels of blue light. LEDs can have varying levels of blue light. The correlated color temperature (CCT) which is found on package labels can be a helpful but not foolproof tool. LEDs with a CCT below 3000K, which appears as warm white, are more likely to have less blue light than LEDs with a higher CCT that appear as cool white. The limitation is that CCT is a measure of appearance rather than spectral distribution and depending on the technology, it is possible for a bulb with a low CCT to have high levels of blue light.
Screens from electronic devices are also a source of blue light and should be considered when determining your overall exposure.
The color rendering index (CRI) is another metric that can help you identify a full spectrum lightbulb. The CRI represents the light’s ability to reproduce the colors of objects as they appear in natural sunlight. The higher the index, up to 100, the closer they are to natural sunlight. The California building code for new construction requires a CRI of 90 or above.
Flicker
Flicker is the rapid and repeated change over time in the brightness of light. Some flicker is detectable by the eye and some is invisible. Health effects include headaches, impaired vision and even seizures. Children and the autistic can be especially sensitive. (source) Incandescent lights have no flicker and fluorescent lights can have high levels of flicker. LED levels can vary. The quality of components used in LED technology can determine the amount of flicker so higher price points can be an indicator of less flicker but not a guarantee.
Recommendations
Maximize natural sunlight in your home to reduce the need to use electric lighting.
Choose incandescent bulbs when available. If you live in a state that doesn’t ban incandescent bulbs you can find a fairly broad selection at the following sites:
Avoid using fluorescent bulbs and if you have them, dispose of them at special recycling facilities.
When using LED lights choose high quality brands with a CCT at or below 3000k and a CRI above 90. Ideally, test for dirty electricity before using.
Consider introducing blue light into certain rooms at certain times of day to mimic natural daylight exposure. You can read more about blue light timing here and here.
Eliminate all light sources when sleeping, particularly from blue light sources such as electronic devices.
Clean up broken light bulbs using gloves and a broom to avoid toxic exposure. If you break a CSL, follow EPA guidelines.
References
Building Biology Institute. Electric Light Factsheet. https://buildingbiologyinstitute.org/free-fact-sheets/electric-light/
Building Biology Institute. Human Response to Light Factsheet. https://buildingbiologyinstitute.org/free-fact-sheets/human-response-to-light/
Schiller, Anja. Electric Light Options and Health Impacts. Building Biology Institute. https://buildingbiologyinstitute.org/course/electromagnetic-radiation/electric-lighting-options-health-impacts/
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