A Study into the Effects of Light on Children of Elementary School Age
A Case of Daylight Robbery
(This study was initiated, funded and distributed by Policy and Planning, Branch Planning and Information Services Division, Alberta Education, 11160 Jasper Avenue, Edmonton, Alberta T5K OL2--February, 1992)
The photobiologic action spectra of greatest importance to humans ranges from 290 to 770 nm. Skin reddening and vitamin D synthesis occurs in the range of 290 to 315 nm. Tanning or pigmentation of the skin and reduction of dental caries occurs in response to band light in the band from 280 to 400 nm. Vision is most sensitive to light in the 500 to 650 nm range (yellow-green light). Bilirubin degradation occurs in response to light in the 400 to 500 nm range (blue light). Natural light provides the spectral energy distribution necessary for all of these biological functions. Full-spectrum fluorescent illumination also provides substantially all of the spectral energy distribution although light levels are much lower than daylight levels. The spectra of incandescent, cool-white fluorescent, and high pressure sodium vapor light sources appear to fall short of covering the entire photobiologic action spectra of importance to human beings.
For people who are outdoors for a significant part of each day, the quality of indoor lighting to which they are exposed may be of little consequence. Their needs for natural light stimulation may be adequate. But for people who spend almost all of their time indoors, and with outdoor exposure limited to morning and evening light, there may be a need for artificial lighting that is supplemented with light stimulation in the spectrum areas of energy deficiency especially blue (440 to 440 nm). Wurtman (1985: xi) very articulately describes the need for clear policy- making guidelines and better understanding of light and its effects on people by first posing a question, Should limits be placed, based on health considerations, on the artificially illuminated lighting environments under which people may live and work?
A Summary of Significant Research Findings
Alberta's Light Study 1987-1991
A number of different types of data were collected from the students including: age, sex, dental histories, nutrition histories, general health, growth and development histories (age at onset of menarche, height, weight, body fat, skin types), vision histories, attendance histories, and scholastic achievement histories. The study points to significant differences between lighting types when it comes to development of dental caries, gains in height, gains in weight, gains in body fat, gains in achievement, and improvements in attendance as being related to classroom lighting types. Specifically it was found that:
1. The effect on children of receiving trace amounts of UV radiation in their classrooms amounted to 1.75 fewer caries (cavities) per child per year than was the case in the non-UV schools.
Site 1 Site 2 Sites 3/5 Site 4
A number of significant differences in attendance are to be noted. Site 2 (full spectrum) and Sites 3 and 5 (full spectrum with UV supplement) had significantly better attendance than Site 1. The difference amounts to approximately 3.2 days per year. One might conclude that an absence of 3.2 days is about the length of time that it would take to recover from a severe cold.
The lowest achievement gains are to be found at Site 1 while the greatest gains are found at Site 2 and Sites 3 and 5.
A two-tailed t test comparison of total achievement gains (combined sub scores on Canadian Test of Basic Skills) measured in grades between June 1987 and June 1989). Levels of significance beyond the 0.05 level are in color.
Putting the Findings into Perspective
This study has identified a number of such effects differences in the rate of dental caries (cavities) development, differences in rates of attendance, differences in the age of the onset of menarche, differences in height, weight, and body fat gains, and differences in scholastic achievement. One might conclude from these findings that natural light is important to the development and well-being of people and to imprison people in spaces lit only with artificial lights designed solely for efficiency amounts to a clear case of daylight robbery.
The relationship of light to the physical well-being and health of people is not surprising. Nor are the effects of color surprising. Blues of the sky, the greens of vegetation, and earth tones are part of our natural environment. It seems reasonable that most people will be most comfortable and relaxed in environments that most closely simulate these conditions.
Natural light provides the spectral energy distribution necessary for all of these biological functions. Likewise, full-spectrum fluorescent illumination provides substantially all of the spectral energy distribution although light levels are much lower than daylight levels. The spectra of incandescent and cool-white fluorescent sources appear to fall short of covering the entire photobiologic action spectra of importance to a human being.
While high doses of UV light may contribute to health-related problems, the doses received from the lights of this study from an 8 hour day are the equivalent of less than 15 minutes in the sun. This level is well within the ranges recommended as healthy for most individuals.
Educational Applications and Cost Savings Benefits
Based on the 1981 to 1985 research it was concluded that there could be significant benefits for education in several areas. On the basis of the daily per pupil educational expenditure in 1984-85 (i.e., $21.42 per pupil space per day) and a with difference of 9.49 days of absence per year for students under different lighting systems, the cost of having these spaces vacant because of these absences amounts to $203.28 per pupil per year (i.e., an average expenditure of $203.28 is made to provide a pupil space which is not used). On the basis of the reduced dental caries, a further saving was calculated at $ 116.75 per pupil per year. Combined, these benefits total $320.03 per pupil per year.
Inasmuch as the cost of providing trace amounts of ultraviolet in classrooms amounts to no more than $30.00 per student per year, there is a net social benefit of $290.03 per pupil per year. It was further concluded that if these benefits could be generalized to all students in Alberta (approximately 430,000) the net social benefit would approach $125,000,000 per year. Moreover, these findings may be generalizable to other regions of Canada, the northern United states, areas frequently shrouded in fog, and other geographical locations where the daily availability of natural ultraviolet light is minimal for extended periods of time.
Light Helps Pupils Learn!
Learning rates were 26 percent higher in reading and 20 percent higher in math in rooms with the
Psychologists and energy efficiency experts alike have long suspected that something as simple as sunshine may help people work more efficiently, learn more, call in sick less often and sell more. The research, conducted by an energy consulting firm for the California Board for Energy Efficiency and Pacific Gas and Electric Co., is one of the largest and most rigorous attempts to test those suspicions.
"My guess is this will make a huge impact on school design in the next few years", said Arthur Rosenfeld, a senior adviser for energy efficiency for the U.S. Energy Department. While stressing he hadn't yet read the studies, Rosenfeld described them as "a star group", and said their level of certainty is "very, very impressive.." From the Star Bulletin in Honolulu, Hawaii