An often overlooked advantage of LEDs

An often overlooked advantage of LEDs

Now most people already know that LED is a new light source that saves energy and reduces emissions. But there is another great advantage that is often overlooked, that is, no pollution and environmental protection.

We know that mercury is an extremely toxic substance. However, almost most of the currently used high-efficiency electric light sources contain mercury. The mercury content of various electric light sources is shown in the following table:

Mercury has a very low boiling point and can evaporate at room temperature. When a discarded light source is broken, it immediately emits mercury vapor to the surrounding area, which can instantly make the mercury concentration in the surrounding air reach 10-20 mg/m3, which is 1,000 to 2,000 times higher than the maximum allowable concentration of mercury in the air stipulated by the state (0.01 mg/m3). According to a study on mercury by Stanford University in the United States, 1 mg of mercury is enough to contaminate 5454.5 kg of drinking water, making it unsafe for drinking. The consequences of air and water pollution caused by mercury are very serious. After being eaten by aquatic organisms, CH3Hg will be generated, which is a highly toxic substance. Just half an ear spoon can kill a person. Mercury itself can damage the central nervous system, and the effect of reproductive defects it causes is also very serious. Mercury can also damage the kidneys and liver, and can even cause death under sufficient dosage conditions. Mercury can be transferred in different ways in the soil, water flow, and even in the atmosphere and food chain. Therefore, the persistence, easy migration and high bioaccumulation of mercury make mercury one of the most concerned environmental pollutants in the world. The most serious mercury poisoning incident in history is the Minamata disease incident in Japan, when hundreds of people died because the water in Minamata Bay was contaminated by mercury. Now the Japanese government has learned a lesson and requires all discarded fluorescent lamps to be treated for toxic substances, and requires people who buy ordinary fluorescent lamps to pay double the price to advance the cost of this toxic substance treatment.

Recently, the Chinese government distributed 100 million energy-saving lamps for free. Although the mercury content of low-mercury energy-saving lamps specially made abroad can be reduced to less than 5mg (it is not known whether the low-mercury energy-saving lamps distributed by the Chinese government are such), it does not reduce their harmfulness at all, because the mercury content of such low-mercury energy-saving lamps is enough to pollute 27.27 tons of drinking water. And 100 million energy-saving lamps are enough to pollute 2.7 billion tons of water, which is equivalent to the drinking water of the whole nation for several years.

Because China does not have a special recycling organization and recycling regulations, most fluorescent lamps and energy-saving lamps are buried like ordinary garbage. Regardless of whether they are fluorescent lamps or energy-saving lamps, they use extremely fragile glass as the shell, so the mercury in them will definitely escape. Moreover, due to the high specific gravity of mercury, it is easy to sink and penetrate into the groundwater, and then be drunk by people and animals. The consequences are disastrous. In particular, the general public knows almost nothing about the harmfulness of mercury. The following photo was taken by the author at a bus stop in the downtown area of ​​Xujiahui, Shanghai. The picture shows a broken billboard with a lot of glass fragments of fluorescent lamps. Moreover, the author walked by there every day, but no one dealt with it for more than two weeks. It can be seen that the relevant departments are also ignorant of the harmfulness of broken fluorescent lamps.

In addition, all electric light sources that use mercury vapor to emit light use electrons to bombard mercury vapor to produce ultraviolet rays. This ultraviolet light is also a kind of environmental pollution. Its main wavelength is 2537 angstroms = 2537x10-10m = 253.7nm, called UV-C ultraviolet rays. About 60% of the consumed electrical energy can be converted into ultraviolet rays, and the rest of the energy (about 40%) is converted into heat energy. The fluorescent material on the inner surface of the lamp tube absorbs ultraviolet light and releases visible light. Different fluorescent materials will emit different visible lights. Generally, the efficiency of converting "ultraviolet light" to "visible light" is about 40%. Therefore, the efficiency of fluorescent lamps is about 60%×40% = 24%, which is about three to five times that of tungsten filament lamps of the same power. That is to say, there are still 100%-(40%＋24%)=36% of ultraviolet rays that are not converted into other energy and directly radiate on the glass tube wall. 36% of ultraviolet rays are about 94% depleted through the glass tube wall, so there may be 36%×6%=2.16% of UV-C passing through the glass tube. UV-C is considered Deep UV to the human body and is extremely harmful. GE General Electric of the United States recommends that humans should not be exposed to fluorescent lamps for more than 16 hours. The damage of ultraviolet rays to the human body is a lifetime accumulation. This is very important for those girls who love beauty.

In addition, energy-saving lamps and fluorescent lamps also have microwave radiation. A Taiwanese scholar actually measured the microwave radiation of energy-saving lamps in his home. The results are as follows: when the lights are not turned on, the microwave radiation measured in the room is 0.011 microwatts per square centimeter (0.011μW/cm2) within the bandwidth of 0.5 to 3GHz. After turning on a 60W incandescent lamp, the microwave value remains unchanged; after switching to a 15W energy-saving lamp, the microwave value is as high as 50 microwatts per square centimeter (50μW/cm2), which is 5,000 times that of an incandescent lamp. When it is replaced with a 26W energy-saving lamp, its microwave radiation value is as high as 100 microwatts per square centimeter (100μW/cm2), which is 10,000 times that of an incandescent lamp, almost higher than a mobile phone. The national microwave hygiene standard is 50 microwatts/cm2, so it has exceeded the national microwave hygiene standard. The electromagnetic wave intensity of a 15-watt energy-saving lamp is about 70 milligauss, and that of a 26-watt energy-saving lamp is 80 milligauss. The electromagnetic wave intensity of a 60-watt incandescent lamp is almost zero. Because the mechanisms of fluorescent lamps and energy-saving lamps are exactly the same, the microwave radiation of fluorescent lamps will only be higher than that of energy-saving lamps, but never lower than that of energy-saving lamps. This microwave radiation can cause dizziness. As for what other diseases it may cause, it is still unknown. Japanese research shows that people who work in front of computers for a long time are twice as likely to develop glaucoma as others. You should know that the LCD monitor of a computer also uses a cold cathode fluorescent lamp similar to a fluorescent lamp as a backlight.

LED lamps are completely mercury-free and environmentally friendly products, and they also have no ultraviolet radiation, but their driving power has very low microwave radiation. The use of this new light source completely eliminates all kinds of pollution, so it can be called a true "green light source".