A Study into the Effects of Light on Children of Elementary School Age – A Case of Daylight Robbery

Executive Summary

Yes! Light affects people in some surprising ways. Some would even go so far as to say that light is nutritious. In order to get a firmer grasp on some of these effects of light on people, a study of the effects of light on children of elementary school age was undertaken by Alberta Education between June 1987 and June 1989.

This study was intended to replicate the 1981-1985 study wherein it was found that trace amounts of ultraviolet light served to reduce the development of dental caries. Five schools were involved in this study (the specific schools have not been named in order to protect the students from undue notoriety.) The study has been guided by a Steering Committee with representatives from Alberta Occupational Health and Safety (Radiation Health Services); the Faculty of Dentistry, University of Alberta; Duro-Test Canada, Inc.; and Alberta Education (School Buildings Services and Policy and Planning Branches).

The study was designed to test the null hypothesis – different light types (full spectrum fluorescent, full spectrum fluorescent with ultraviolet light supplements, cool-white fluorescent, and high-pressure sodium vapor) have no differential effects on Division II students’ dental histories, growth and development histories, vision histories, scholastic achievement histories, or attendance histories when compared over a two-year period.

Upper elementary students were selected for the study for three reasons: upper elementary students were involved in the first study completed by Alberta Education, elementary students tend to remain in home rooms most of the time which makes it easier to ensure that they remain under selected lighting types, and upper elementary students are going through significant body changes (including eruption of permanent teeth).

Schools were chosen either because they had unusual lighting systems (the case with high pressure sodium vapor site) or they were willing to have their lighting systems modified through Alberta Education’s Building Quality Restoration Program.

Dental and nutrition data were collected by the Faculty of Dentistry, University of Alberta as a part of a contract with Alberta Education. Health-related data were collected by a Registered Nurse under contract to Alberta Education. Attendance and achievement data were collected and analyzed within the Policy and Planning Branch of Alberta Education. Tests of the spectral quality of the lights in schools involved in the study were completed by Radiation Health Services of Alberta Community and Occupational Health.

Major findings of the study include:

  • Over a two year period students receiving ultraviolet light supplements developed 0.17 decayed surfaces while the non-UV group developed 1.53 decayed surfaces. Those students receiving ultraviolet light supplements also demonstrated the best attendance, the greatest gains in height and weight, and the best academic achievement.
  • Over a two year period students under high pressure sodium vapor lighting had the slowest rates of growth in height (2.1 cm less than students receiving a ultraviolet light supplement), and achievement (a gain of 1.6 years in comparison to the 2.0 years which was the average of all other sites). They also had the lowest percentage of attendance (94.3 percent) while the other sites had attendance patterns of 95.9 percent, 95.9 percent and 96.2 percent. The difference of 1.6 percent between the poorest and next best site translates into 3.2 days per year (about the time needed to recover from a major cold).

These findings support the conclusion that lighting systems are not neutral – they have non-visual effects on people who are exposed to them over long periods of time.

This report concludes with a section devoted to a discussion of the ways by which the findings of this study might be used.

Three recommendations are supported by the findings of this study. First, continued research should be carried out into the non-visual effects of light. Second, the impact of the completed studies should be examined with a view to providing the best and safest lighting systems for existing classrooms and new or redesigned classrooms. Third, a clearing house of information should be created with respect to the non-visual effects of light – and perhaps color – and related implications for schools and school design.

Warren E. Hathaway, John A. Hargreaves, Gordon W. Thompson, Dennis Novitsky

This study was initiated, funded and distributed by the Policy and Planning Branch, Planning and Information Services Division, Alberta Education, 11160 – Jasper Avenue, Edmonton, Alberta T5K 0L2. February, 1992


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