Correspondence
Sick Building Syndrome
N Engl J Med 1993; 329:503-504August 12, 1993
- Article
To the Editor:
In their report on the sick building syndrome (March 25 issue),1 Menzies et al. conclude that “increases in the supply of outdoor air did not appear to affect workers' perceptions of their office environment or their reporting of symptoms considered typical of the sick building syndrome.” The paper, however, lacks sufficient information to permit any conclusions to be drawn.
All the buildings had outdoor-air supplies above the minimum recommended by the American Society of Heating, Refrigerating and Air-Conditioning Engineers of 20 ft3 (0.57 m3) per minute per person. The authors said that the “buildings used in this study were not selected on the basis of a previous identification of the building as sick.” Therefore there were no “sick” people on whom to test the hypothesis. The conclusions from this study cannot be applied to buildings whose outdoor-air supplies are below the standard of 20 ft3 per minute per person. The questionnaires included questions on lighting, noise, and space -- factors not likely to be altered by ventilation2,3. On the other hand, the ventilation systems were not described, nor was the location of air-intake vents, the potential for the entrance of contaminants into the intake vents, the system design (constant or variable air volume), the condition of ducts (e.g., whether they had fraying fiberglass liners), or the filtering devices.
It is unclear how the samples for the measurements of contaminants were collected (duration, timing) or analyzed (e.g., for hydrocarbons). Ventilation systems can cause and disseminate particulate substances and microbial components, so such data should have been included. In addition, the smoking policies and methods of sequestering tobacco smoke were not adequately discussed.
3 ReferencesPhilip A. Edelman, M.D.
University of California, Irvine, Medical Center, Orange, CA 92668Thomas Hethmon, M.S., C.I.H.
Phelps Dodge Corporation, Phoenix, AZ 850041
Menzies R ,Tamblyn R ,Farant J-P ,Hanley J ,Nunes F ,Tamblyn R . The effect of varying levels of outdoor-air supply on the symptoms of sick building syndrome. N Engl J Med 1993;328:821-827
Full Text | Web of Science | Medline2
Morey PR ,Shattuck DE . Role of ventilation in the causation of building-associated illnesses. Occup Med 1989;4:625-642
Medline3
Lebowitz MD, Quackenboss JJ, Soczek ML, Colome SD, Lioy PJ. Workshop: development of questionnaires and survey instruments. In: 1989 Design and protocol for monitoring indoor air quality. Special technical publication no. 1002. Philadelphia: American Society for Testing and Material, 1989:203-16.
To the Editor:
The conclusions of Menzies et al. are supported by their data. But, because they used such high ventilation rates to test their hypothesis -- rates well above the current recommended minimum and rates at which no symptoms would be expected -- their conclusions are trivial. Unfortunately, these trivial results are being used by some to suggest that ventilation has nothing to do with the symptoms that building occupants may have. This mistaken impression leads to the mistaken conclusion that the sick building syndrome results from imaginary symptoms, unrelated to the building's environment.
Joe F. Boatman, Ph.D.
AE Associates, Inc., Greeley, CO 80634To the Editor:
Selection bias could have been present in the group studied by Menzies et al., since some self-selection of participants is suggested by the high percentage of atopic persons and current smokers included. Furthermore, since only 637 occupants (41 percent) completed all six questionnaires, they may be a self-selected group that could have unduly influenced the results.
John F. McCarthy, Sc.D., C.I.H.
Jack E. Farnham, M.D., M.P.H.
Environmental Health & Engineering, Inc., Newton, MA 02158To the Editor:
In the study by Menzies et al., the overall illness rate (39 percent), the preponderance of symptoms in women, and several of the reported symptoms (e.g., headache, fatigue, and difficulty concentrating) are consistent with a psychogenic group illness. Moreover, the strong temporal trend toward the diminution of symptoms during the course of the study could result from the psychological effect on the study group of knowing that investigators were carrying out an experimental intervention that included self-administered questionnaires. Our previous studies of psychogenic group illnesses have demonstrated the importance of previous and current psychological experience,1,2 concern about environmental contaminants,3 and especially social relationships2 as factors contributing to the spread of symptoms.
The observation that “the frequency of symptoms among workers in `problem' buildings was similar to that among workers in `non-problem' buildings” further supports the psychogenic hypothesis. Although environmental factors may explain some reported symptoms of sick building syndrome, further study of psychological and social factors is indicated.
3 ReferencesGary W. Small, M.D.
UCLA Neuropsychiatric Institute, Los Angeles, CA 900241
Small GW ,Nicholi AM Jr . Mass hysteria among schoolchildren: early loss as a predisposing factor. Arch Gen Psychiatry 1982;39:721-724
Web of Science | Medline2
Small GW ,Propper MW ,Randolph ET ,Eth S . Mass hysteria among student performers: social relationship as a symptom predictor. Am J Psychiatry 1991;148:1200-1205
Web of Science | Medline3
Small GW ,Borus JF . Outbreak of illness in a school chorus: toxic poisoning or mass hysteria? N Engl J Med 1983;308:632-635
Full Text | Web of Science | Medline
To the Editor:
The Methods section of the paper by Menzies et al. contains no mention of informed consent or of approval of the experiment by the institutional review board. Is the lack of this information an oversight, or was there no informed consent or institutional review? If there was no oversight by the institutional review board, some ethical questions are raised by the study design.
Jonathan S. Bromberg, M.D., Ph.D.
Medical University of South Carolina, Charleston, SC 29425Author/Editor Response
The authors reply:
To the Editor: In response to Dr. Bromberg, our study was approved by the ethics committee of the Department of Epidemiology and Biostatistics of McGill University.
In response to Drs. McCarthy and Farnham, the estimate of the effect of changes in the outdoor-air supply was based on a comparison within subjects of the frequency of symptoms under the various ventilation conditions. This minimizes potential selection bias. In addition, in over 80 percent of the instances in which a worker did not complete the weekly questionnaire, the worker was found to be absent from the building on that day. Therefore, the participants had the greatest degree of exposure and were potentially the most susceptible, because they were more likely to smoke or to have atopic illness. This should have increased the likelihood of finding a benefit of increased outdoor-air supply.
Regarding the comments of Dr. Boatman, we believe it is misleading to characterize our results or conclusions as trivial, because the substantial prevalence of symptoms among workers was not altered although the amount of outdoor air was doubled. We did not think it was ethical or a research priority to study ventilation rates below 20 ft3 per minute per person, because this is a well-accepted standard.
We agree with Dr. Edelman and Mr. Hethmon that the conclusions cannot be applied to ventilation rates of less than 20 ft3 per minute per person, as we stated in our discussion. We believe that the definition of a “sick building” is imprecise; in a survey of 47 buildings in the United Kingdom, the prevalence of symptoms was very similar in “problem” buildings and “non-problem” buildings1. Because of space limitations, we did not describe the ventilation systems, but the dissemination of street-level contaminants was unlikely, because the air-intake vents were located on the roof of three of the study buildings and on the 11th floor in the fourth. Standard methods of collection and analysis recommended by the National Institute for Occupational Safety and Health were used as described in previous publications2. All buildings had a no-smoking policy, but the actual level of smoking was not measured because, at the time of the study, this policy had only recently been instituted in several buildings and was still controversial.
Finally, we disagree strongly with Dr. Small's notion that the sick building syndrome must be a psychogenic group illness simply because the symptoms were not associated with outdoor-air supply. The symptoms were associated with the temperature, relative humidity, and air velocity in our study, as reported by others3-5. In addition, building-wide changes in outdoor-air supply may be less important than local conditions or the microenvironment of each worksite6. However, the cause of sick building syndrome remains unclear, and we agree with Small's recommendation for continued study.
6 ReferencesRichard Menzies, M.D.
Robyn Tamblyn, Ph.D.
McGill University, Montreal, QC H3A 1A3, Canada1
Burge S ,Hedge A ,Wilson S ,Bass JH ,Robertson A . Sick building syndrome: a study of 4373 office workers. Ann Occup Hyg 1987;31:493-504
CrossRef | Web of Science | Medline2
Farant J-P, Bedard S, Tamblyn RT, et al. Effect of changes in the operation of a building's ventilation systems on environmental conditions at individual workstations in an office complex. In: Walkinshaw DJ, ed. Proceedings of the Fifth International Conference on Indoor Air Quality and Climate, Toronto, July 29-August 3, 1990. Vol. 1. Toronto: Canadian Mortgage and Housing, 1990:581-5.
3
Jaakkola JJK ,Heinonen OP . Sick building syndrome, sensation of dryness and thermal comfort in relation to room temperature in an office building: need for individual control of temperature. Environ International 1989;15:163-168
CrossRef | Web of Science4
Wyon DP ,Andersen I ,Lundqvist GR . The effects of moderate heat stress on mental performance. Scand J Work Environ Health 1979;5:352-361
CrossRef | Web of Science | Medline5
ASHRAE standard 55-1981: the thermal environment conditions for human occupancy. Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, 1989.
6
Hodgson MJ, Collopy P. Symptoms and the micro-environment in the sick building syndrome: a pilot study. In: The human equation: health and comfort. Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, 1989:8-16.
