Lighting hidden dangers, juvenile vision killer?

Beijing City Board of education before the date through the official micro-blog announced that this year the city will be allocated 96 million 352 thousand yuan of special funds, support 16 counties in primary and secondary schools at the end of August to complete the classroom and the lighting transformation, improve the eye health effect to ensure students' classroom lighting.

Reporters learned that the Beijing 2010 national physical fitness monitoring results Bulletin shows that the city's primary and secondary school students visual acuity detection rate was 60.2%, of which the high school students was 81.89%, junior high school students, primary school students in the school of medicine, the number of students was 43.5%. Compared with the results of the Fifth National Students' physical fitness and health survey in 2005, the rate of visual acuity in Beijing high school, middle school and primary school students increased by 7%, about 19% and about 27%, respectively.

Is there a direct link between lighting and juvenile myopia? What is scientific and healthy lighting?

Human eye requires "light health"

In May 1, 2011, China began to implement the "primary and secondary school classroom lighting and lighting health standards", requiring classroom classroom desktop illumination should reach 300Lx, the blackboard surface illuminance should reach 500Lx.

However, the city of Beijing, district level two of the city's primary and secondary school classrooms in the classroom lighting environment health testing results show that the classroom or blackboard lighting conditions are not qualified schools there are 1496. The primary and secondary school classrooms in the classroom average illumination intensity of 60.3%, the average pass rate of the blackboard is only about 22.9%.

"Light health" emphasizes a more scientific approach to lighting. In addition to meet the basic functional requirements of lighting, but also to consider the requirements of physical and mental health, such as UV, glare, etc.. Wang, director of Ophthalmology, An Zhen Hospital, Beijing, told the China Science news.

From the physiological point of view, the human eye is like a precision optical instruments' ', the brightness range can feel very wide, can be distinguished from a few thousandths of Bennett until millions of nit objects. He said.

During the day, when the ambient brightness of 10 thousand nits, the human eye can distinguish the brightness range of about 200 to 20 thousand nits, lower than the brightness of 200 nits will be felt as black; night environment of 30 nits, brightness range resolution is 1 to 200 nits, then the brightness of 100 nits will cause a bright feeling below, only the brightness of 1 nits was caused by black feeling.

The visual perception of human needs to rely on the regulation of pupil and light-sensitive cells. Pupil according to the intensity of external light to adjust its size, photosensitive cells are divided into cone cells and rod cells, the latter is 10 thousand times the sensitivity of the former. In the strong and weak light, the pupil and the photosensitive cells regulate each other, so that the light flux to the retina to maintain moderate. Therefore, the light is too strong or too weak will have an adverse impact on the eyes.

"Daily lighting must be in accordance with the laws of human vision and eye health, in the case of lighting quality does not reduce the use of energy, to achieve 'green lighting', this is a scientific, healthy lighting. "China Research Institute of building science building optical laboratory surnamed Zhang, experts said.

The hidden trouble in daily life"

"Healthy lighting highlights the brightness and spectrum of light. From the functional point of view, when the light is too dark, people will instinctively close to the visual target, time for a long time, will naturally make the eye refractive system changes, resulting in myopia. Wang Jun said.

However, too much light can damage vision. In daily life, reading and writing requires only 100 meters. While reading in the sun, lighting up to 80 thousand ~ 120 thousand M candle, is the daily lighting degree of 800 ~ 1000 times.

Long term reading in the strong light, intraocular muscle over regulation, will promote the occurrence and development of myopia, strong light damage to the retina, especially macular area, so that visual acuity decreased, and even cause permanent vision loss.

For a long time in the light flash under the reading work, also can make the pupil sphincter and the retina due to excessive use of fatigue, pain, or even damage the optic nerve, causing dizziness headache, upset or nervous, tachycardia.

The waveform of AC power grid in China is 50 times per second (up to 50 Hz). Fluorescent tube with 50 Hz of electricity, there will be a flash of light every second for 100 times. The light and dark intensity caused by the alternating current frequency will cause great harm to the eyes of people working in the light environment for a long time.

If you use the computer under the light, usually inductance ballast fluorescent flash and the screen frame flashing overlap, the formation of optical resonance, greater damage to the human visual system. As a result, the European Electrotechnical Commission as early as 1997 banned the use of fluorescent ballasts in the office of the computer screen fluorescent lamp.

The spectrum of lighting will also have an impact on vision. The spectrum of the sun is 100Ra, the object in the light of the sun, can show the true color. At present, the design requirements of the building lighting requirements in the living room and office space, the spectrum of light reached 80Ra. Even so, under the irradiation of the electro-optic source, the color will still have varying degrees of distortion.

"From a technical point of view, the better the lighting spectrum and the spectrum of the sun. However, a single light source is difficult to have such a spectral range. A lot of incandescent bulbs, including LED's lighting source, are not in agreement with the solar spectrum. Therefore, it is unhealthy for the human eye to be exposed to the environment for a long time. Said Bai Tingzhu, Professor, School of optoelectronics, Beijing Institute of Technology.

At the same time, indoor lighting must avoid or reduce glare interference. If the lamps, windows or other areas than the general brightness of the ambient brightness is much higher, people will feel the glare