Are flickering fluorescent lamps dangerous

Are energy-saving lamps and fluorescent lamps harmful to your health?

Extra article> energy saving lamps

Author: Dr. Rüdiger Paschotta

This article is suitable as an in-depth counselor for everyone who is worried about possible damage to health from energy-saving lamps.

Fears are repeatedly expressed that the use of energy-saving lamps and other fluorescent lamps could be harmful to the health of the user or to the environment. In some circles this is even made explicitly. Various fears are discussed in detail here.

Under Energy saving lamps are always understood in the following compact fluorescent lamps with integrated ballast, so not other energy-saving lamps such. B. based on light emitting diodes (LEDs).

The danger of mercury

Energy-saving lamps contain mercury, but far less than various old electronic devices.

Energy saving lamps contain small amounts of mercury. Since 2012, 3.5 mg (milligrams) of mercury per lamp have been permitted in the EU; before that it was 5 mg. Larger fluorescent lamps can contain up to 10 mg, and with metal halide lamps it can be quite a bit more, depending on the power class. For comparison, the (now banned) mercury thermometers contained z. T. well over 1000 mg.

The article [1] shows in detail that the quantities of mercury in energy-saving lamps and other fluorescent lamps do not pose any significant health risk. Even if a lamp is broken in a living room and the mercury escapes, acute or chronic mercury poisoning is not to be expected, as only a tiny part of the mercury is absorbed by the body. (A lamp that is broken during operation releases significantly more mercury than gas, but normally at most a tiny part of it is inhaled, since the mercury is distributed over tens of thousands of liters of air.) Such accidents do not contribute significantly to the overall mercury exposure; it is mainly caused by food (especially fish) and amalgam fillings for teeth.

As a precautionary measure, any unnecessary exposure of the body or the environment to mercury - even if it is not specifically dangerous - should be avoided. It is therefore advisable to ventilate the room thoroughly after a lamp breaks and only then to re-enter it in order to carefully remove the remains of the lamp. It is also mandatory to dispose of the lamps properly after use and not to throw them in the household waste - although other sources contribute far more to the mercury pollution of the waste.

Unfortunately, many lamps are not disposed of properly after use, but end up in household waste. However, this in no way leads to dramatic burdens. A recent study in Switzerland showed that the complete disposal of all energy-saving lamps in this way in Switzerland would only increase the mercury pollution of all municipal waste by around 1% in the long term. This confirms the result of an earlier study from Austria.

The biggest problem with mercury comes from coal-fired power plants, and incandescent light bulbs contribute much more to that than energy-saving light bulbs.

The world's largest mercury pollution is incidentally caused by coal-fired power plants, while lamps of all kinds only make a marginal contribution. Since energy-saving lamps reduce electricity consumption (compared to incandescent lamps) and thus help to avoid several large coal-fired power plant units in the EU, they even contribute to a largely improper disposal reduction contributes to the mercury pollution of the environment.

The extraction of mercury is also associated with environmental pollution and, in some cases, with the endangerment of workers and residents. However, only a very small part of the global mercury production is used for lamps, so that the lamps only have a correspondingly small influence on this.

The above-mentioned facts do not prevent certain circles from making claims about alleged extreme health risks from the mercury in the lamps [2], without being able to substantiate them properly.

The light spectrum of the lamps

Visible light spectrum

White is not always white. There are energy-saving lamps with different color temperatures, which should be selected correctly depending on the application. Warm-tone lamps are most common in the home, but are usually not the right choice in offices.

White light is a mixture of light of different colors - from red to orange, yellow and green to blue and purple. With sunlight and also with incandescent lamps, all colors are represented fairly evenly - the spectrum is continuous. In the case of energy-saving lamps and other fluorescent lamps, on the other hand, the light spectrum is more or less clearly structured, i. H. some color components are more strongly represented, while others are weaker. In addition, the Color temperature, which allows a rough overall statement about the type of spectrum (more precisely: the relative strength of the red and blue components) can be different depending on the phosphor used: Warm tone lamps have a similar color temperature as incandescent lamps (e.g. 2700 K) while Cold tone lamps (“Neutral white”) with 5000 K or more are more like sunlight at noon.

The different light spectra repeatedly give rise to fears about health impairments, which, however, turn out to be unfounded on closer analysis, e.g. Sometimes based on misunderstandings:

The color temperature is relevant to health. What the “healthiest” color temperature is, however, depends crucially on the situation.
  • The color temperature, in particular the higher content of blue light at a high color temperature, is initially of relevance to health: the blue component suppresses the formation of melatonin in the human body and thus contributes to alertness or reduction of tiredness - similar to sunlight. This effect of cold-tone lamps is desirable in the office, but when used in a living room in the evening it can make it difficult to fall asleep later. A health problem - increased fatigue at work or disturbed sleep - arises from the wrong choice of color temperature, and not from the fact that the light of certain lamps would be harmful in itself. Energy-saving lamps and other fluorescent lamps even offer the advantage that they are available with very different color temperatures and can therefore be easily adapted to the respective application. In the case of incandescent lamps, on the other hand, only the already low color temperature can be further reduced by dimming, which also makes the light output and energy efficiency even worse.
Most energy-saving lamps are out of the question where the color tones of objects have to be assessed precisely. However, this has nothing to do with health.
  • Since the eye essentially only contains three different types of sensors for different colors, it cannot analyze the spectrum of light in detail; the brain only “learns” how strongly the individual sensors have been stimulated, but not exactly by which color components of the light. It is therefore practically impossible to distinguish the color impression from white light sources with very different spectra with the eye as long as they have a similar color temperature. For example, a white wall looks practically exactly the same when lit with either a warm-tone fluorescent lamp or an incandescent lamp; on the other hand, the light appears “colder” when a lamp with a higher color temperature (a Cold tone lamp) is selected. Despite the high similarity of the direct impressions of incandescent lamps and warm-tone fluorescent tubes, the color impressions of colored objects that are illuminated with them can be slightly different. This aspect is relevant e.g. B. for an artist's studio, but has no health significance.

There has been various speculations that the structured spectrum of fluorescent lamps could be harmful to health in other ways. However, there are no concrete effects of this kind that are substantiated or verifiably proven by observations. This does not prevent certain esoteric circles from asserting the harmfulness of the light from these lamps. But there is no reasonable reason to believe such speculations, even if they are naturally not refutable.

Macular degeneration from blue light

Is the blue component of energy-saving lamps harmful to the eyes?

Macular degeneration is a disease of the retina that can cause gradual blindness, particularly affecting the central area of ​​the visual field, where otherwise sharpest vision is possible. This disease occurs almost only after the age of 50 and is promoted by various risk factors such as smoking, high blood pressure and probably also genetic factors. It is possible that excessive exposure of the eye to blue light also promotes macular degeneration - possibly more so in patients with an artificial eye lens, which absorbs UV light less than the natural lens.

Harmful effects of short-wave light are quite possible - but more likely with intense sunlight than with artificial light, as this is usually much weaker.

This is where the connection to energy-saving lamps lies: Some of these, namely cold-tone lamps, generate a higher proportion of blue light compared to incandescent lamps, while warm-tone lamps tend to emit even less blue light than incandescent lamps. In comparison with sunlight, the blue component in cold-tone lamps is roughly comparable to the total light intensity, while the total illuminance, i.e. also the absolute amount of blue light, is usually much lower. So if blue light actually promotes macular degeneration, sunlight would be by far the most dangerous, much less light from energy-saving lamps or fluorescent tubes. You would then have to avoid spending time outdoors with a bright blue sky. Most warm-tone lamps (which are preferred in apartments) would even be less of a concern than incandescent lamps.

In purely theoretical terms, it would be conceivable that blue light with very specific wavelengths, as they occur more intensely in fluorescent lamps, would be much more worrying than blue light with slightly different wavelengths. However, there are no specific indications for this; on the contrary, the wavelength dependence for various damage mechanisms is well known and does not match the concerns mentioned. It must therefore be assumed that sunlight is the most questionable - far more than any artificial light for lighting purposes, since the illuminance in sunlight is usually much higher than that of artificial lighting. In the case of artificial light sources, the ones that are most likely to cause unpleasant glare would be the ones that are most likely to cause concern - especially halogen spotlights and some other halogen lamps that you can look directly into. In general, you should avoid looking into uncomfortably bright lights up close.

Winter depression

It is well known that winter depression occurs more frequently in northern countries, where significantly less sunlight is available in winter. A lack of blue light in particular seems to be harmful here, which is why bright lamps with a high proportion of blue light are increasingly being used for therapy. Cold light lamps in the form of fluorescent tubes or compact fluorescent lamps are suitable here, as are certain LED lamps. In many patients this therapy seems to be successful and to make drugs superfluous. This shows that an increased proportion of blue in the light can also be beneficial to health. In this case, cold-light fluorescent lamps would even be beneficial for health - better than warm-tone fluorescent lamps and also better than incandescent lamps.

Ultraviolet light

In fluorescent tubes (also energy-saving lamps), intense ultraviolet light (UV light) is first generated by electrically excited mercury vapor. This is then largely converted into visible light by the fluorescent material on the inside of the tube. Most of the UV light that the phosphor does not absorb is absorbed in the glass tube, so that very little UV light leaves the tube.

Now, in principle, UV light can be harmful to the skin and eyes, but again this can only be assessed by taking into account the quantities. Compared to sunlight, the UV intensity is much lower, which is why, for example, sunburn is impossible even if you stay directly next to a fluorescent lamp for a very long time. (Exceptions are special UV-producing tubes, such as those used in solariums - these emit far more UV light and can definitely have harmful effects.) When it comes to the strain on the eye, it must be taken into account that the pupils are at artificial lighting, which is usually much weaker than full sunlight, open wider. However, the amount of UV light is so small relative to that of visible light that no damage whatsoever is to be expected.

With certain other lamps, in particular with halogen lamps and metal halide lamps without UV-absorbing protective glass, the UV components can be considerably stronger, so that under unfavorable conditions damage to skin and eyes is possible. Therefore, UV protective glasses should always be used.

Most people get the greatest dose of UV light from sunlight and very little from artificial light. The precaution against UV damage must therefore start with sunlight. In particular, the eyes should be protected by sunglasses. If you expose your eyes to uncomfortably bright sunlight by not wearing sunglasses, you run a much higher risk of eye damage than artificial lighting.


The “flicker” of a light source is usually understood to be a sensory impression that arises from rapid fluctuations in the light intensity. On the other hand, if such fluctuations are very rapid (e.g. 100 times per second), they are generally imperceptible. Nevertheless, they are sometimes referred to as (an invisible) flicker. There are differences between different light sources in this regard:

  • Sunlight doesn't flicker, and light from incandescent lamps hardly at all. However, if sunlight z. B. comes to the eye through leaves moving in the wind, this can cause a strong flicker. Of course, this can hardly be harmful.
There is only real flicker with fluorescent lamps when they are defective. Otherwise there are only normally imperceptible fluctuations in brightness. There does not seem to be any convincing evidence that these are harmful.
  • In the case of large fluorescent lamps that are operated with a conventional (non-electronic) ballast, on the other hand, there are mostly pronounced fluctuations in brightness at 100 Hz (i.e. with 100 maxima and minima per second), which, however, are usually not visible. In the case of defective lamps or shortly before the end of their service life, however, a clearly perceptible flicker with lower frequencies can occur. The latter can be annoying, in the long run it can also be harmful to health (e.g. making you nervous), and is a sensible reason to replace the lamp, even if it is still lit.
  • Energy-saving lamps and increasingly larger fluorescent lamps contain an electronic ballast which causes the lamp current to oscillate at a high frequency (e.g. 40 kHz, i.e. 40,000 times per second). The resulting very rapid fluctuations in brightness are small, firstly, because the phosphors have a certain persistence, and secondly, they are much too fast to be perceived. In addition, there is often a clear 100 Hz component (if the smoothing capacitor is just designed), but weaker than in lamps with conventional ballast. A visible flicker arises only through defects or at the very end of the service life.

In principle, it is conceivable that even rapid, imperceptible fluctuations in brightness (e.g. at 100 Hz) have some kind of health impact - negative or positive. I am not aware of any reasonable evidence of this, although there is a flood of apparently pseudoscientific claims about harmfulness on the Internet. It can be assumed that there is no scientifically verifiable proof of this, because otherwise word of this would have to have got around long ago. (Of course, if a reader were to send it to me, I would immediately consider such a receipt, also in this article.)

Incidentally, there are also strong, low-frequency fluctuations in brightness, e.g. B. when the sun shines through leaves that move in the wind. However, this should normally not mean any risk.

In any case, there does not seem to be any reasonable reason to suspect health risks from the actually measurable fluctuations in brightness of some lamps.


The electronic ballasts of energy-saving lamps and some large fluorescent lamps trigger some concerns about electrosmog because they emit relatively high-frequency electromagnetic waves. These waves (or fields) are indeed easily measurable, at least in the vicinity of such a lamp - very similar to many other electrical devices.

Damage to health through electromagnetic pollution is conceivable in principle, but despite the great effort it has not been proven. In view of very real hazards of a different kind (e.g. climatic hazards), it makes more sense to deal with them.

Claims about possible health effects of this "electrosmog" are still unproven despite years of intensive efforts. A wide range of health disorders have been reported and then attributed to electromagnetic waves (by the way, much more often to mobile communications and power lines than for lamps), but the connection between disorders on the one hand and electromagnetic waves on the other hand is unproven. Various studies that claim the opposite suffer from extreme methodological errors. It has even happened that a considerable accumulation of cancer cases was found in the vicinity of a cell phone antenna, but then it turned out that this antenna did not exist at all [3]. A number of other studies on mobile communications did not yield any reliable results either [4]. There is even less data on “electrosmog” from lamps, so there is no reasonable cause for concern.

It is true that, unlike incandescent lamps, energy-saving lamps can exceed the Swedish TCO electrosmog limit for computer screens (which does not apply to lamps). However, it should be noted that the strict TCO limit is in no way based on data on health effects. Rather, it is based purely as a precautionary value on what is technically feasible for screens (which can be easily shielded and operated in close proximity to the user). This is why even significant excesses of this limit value are by no means an indication of health hazards, even if some circles suggest this.

Should the “electrosmog” from energy-saving lamps ever prove to be harmful, this would also apply to a large number of other devices, and drastic changes in the electrical sector would be necessary.

By the way, there is no proven health hazard with electrosmog, but there is a demonstrably “nocebo effect”: Some test persons develop corresponding symptoms of damage (also objectively measurable) when they believe they are exposed to electrosmog - although not at all the case is [10].

Outgassing harmful substances

The quantities must also be observed in the case of outgassing toxic substances. There does not seem to be any evidence of critical quantities.

An institute commissioned by the NDR found in 2011 that at least some energy-saving lamps emit volatile organic compounds such as phenol and styrene during operation [5]. However, there were only significant concentrations in one test chamber with a very small volume of 22.5 liters. In a living room, these substances are distributed over a roughly estimated 1000 times higher volume, so that the pollutant concentrations that arise are negligible compared to those from other sources. Although the measurements appeared to be correct, the results on television were completely misinterpreted. The Federal Environment Agency put these things right and came to the conclusion that there is no health risk [6]. The Stiftung Warentest has also confirmed this.

It has been reported, however, that individual products stink annoyingly, i.e. that they evidently emit significant amounts of some substances. This is unacceptable because of the unpleasant smell that arises, which is why such lamps should be returned to the trade.


Although a large number of possible harmful effects of energy-saving lamps and fluorescent tubes has been alleged, there is no reasonable basis for this. Naturally, it can never be proven that there is not some - perhaps not yet known - health hazard. However, this cannot be a reasonable reason to avoid these lamps, as otherwise an enormous number of other “non-natural” and also “natural” things would have to be avoided. For example, one could hardly demand that only such foodstuffs may enter the trade that has been proven to be harmless to every person under all circumstances; otherwise we would starve to death.

The massive advantages of energy-saving lamps - not least for the environment and health - should not be overlooked despite various concerns about health risks that can hardly be justified.

For the lamps, there is also the fact that concrete benefits for the environment and thus also for our health are undoubtedly proven: Due to the reduced power consumption compared to incandescent lamps, these lamps reduce the operation of coal-fired power plants in particular, which means that large amounts of pollutants that otherwise get into the environment, avoided - including mercury, various other heavy metals and radioactive substances. That is why you are doing the population a disservice if you stir up fears about alleged health risks through the lamps and thus increase other very real dangers. Consider that e.g. In Europe, for example, many thousands of people die prematurely every year from air pollution from coal-fired power plants. The fact that almost all environmentalists see it that way and therefore support the replacement of incandescent lamps with more energy-saving lamps is not the result of a global conspiracy, but rather an insight into the facts.

I emphasize again that I will include every reasonable indication of possible health hazards and, if necessary, correct my assessment. As a scientist (and, by the way, an expert completely independent of the lamp manufacturers), I reserve the right to judge the credibility and persuasiveness of data and arguments myself instead of leaving this to certain followers of esoteric belief systems.

By the way, we also have useful advice articles on various other topics in the energy sector.

Questions and comments from readers

Here you can suggest questions and comments for publication and answering. The author of the RP-Energie-Lexikon will decide on the acceptance according to certain criteria. In essence, the point is that the matter is of broad interest.

If you receive help here, you might want to return the favor with a donation with which you support the further development of the energy dictionary.

Data protection: Please do not enter any personal data here. We would not publish them anyway and we would delete them soon. See also our privacy policy.

If you would like personal feedback or advice from the author, please write to him by email.

By submitting you give your consent to publish your entries here in accordance with our rules.

See also: energy-saving lamp, fluorescent lamp, lighting