The effect of varying levels of outdoor-air supply on the symptoms of sick building syndrome

Causes of change in the health of populations: a biopsychosocial viewpoint

In the current review, a biopsychosocial perspective is applied to current changes in the health of populations. It is proposed that the psychosocial environments either promote health or precipitate disease. Changes in the types of stress that people experience as well as its prevalence over time are discussed. In addition, possible biological mechanisms linking the psychosocial environments to health are presented. "Food for thought" is the possible interaction between the physical/chemical and the psychosocial environments and changes in health of individuals. Clearly, our traditional view of disease mechanisms is not sufficient to understand recent phenomena, such as environmental illness and chronic fatigue syndrome. Issues worthy of further discussions are the role of the "just-in-time" society, where individuals increasingly have to change jobs, cope with reorganizations and increased production pressure, and its impact on health and well-being. Further, in what way can we develop better models to truly assess the impact of an increasingly complex interaction between individual and environmental factors on health? A major obstacle to enhancing our understanding of causes of change in the health of populations is the use of inappropriate or outdated statistical analytical models. Finally, it is suggested that prospectively controlled studies of the impact on health of changes in the health and welfare systems are carried out. This would further add to our understanding of factors contributing to changes in the health of population.

Ventilation rate in office buildings and sick building syndrome

OBJECTIVE

To examine the relation between ventilation rate and occurrence of symptoms of the eyes, nose, throat, and skin as well as general symptoms such as lethargy and headache, often termed the sick building syndrome.

METHODS

A cross sectional population based study was carried out in 399 workers from 14 mechanically ventilated office buildings without air recirculation or humidification, selected randomly from the Helsinki metropolitan area. The ventilation type and other characteristics of these buildings were recorded on a site visit and the ventilation in the rooms was assessed by measuring the airflow through the exhaust air outlets in the room. A questionnaire directed at workers inquired about the symptoms and perceived air quality and their possible personal and environmental determinants (response rate 81%). The outcomes were weekly work related symptoms experienced during the previous 12 months and symptom groups defined either by their anatomical location or hypothesised mechanism.

RESULTS

In logistic regression analysis, the adjusted odds ratio (OR) for any symptom of interest was 3.03 (95% confidence interval (95% CI) 1.13 to 8.10) in the very low ventilation category of below 5 l/s per person and 2.24 (0.89 to 5.65) in the high ventilation category of over 25 l/s per person compared with the reference (15- < 25 l/s). The ORs for ocular (1.27, 1.11 to 1.46), nasal (1.17, 1.06 to 1.29), skin symptoms (1.18, 1.05 to 1.32), and lethargy (1.09, 1.00 to 1.19) increased significantly by a unit decrease in ventilation from 25 to 0 l/s per person.

CONCLUSION

The results suggest that outdoor air ventilation rates below the optimal (15 to 25 l/s per person) increase the risk of the symptoms of sick building syndrome with the sources of pollutants present in mechanically ventilated office buildings. The Finnish guideline value is 10 l/s per person.

The environmental somatization syndrome

Patients with environmental somatization syndrome (ESS) believe that their symptoms are caused by exposure to tangible components of the external environment or by ergonomic stress at work. ESS is distinguishable by mental contagiousness and by the patients' focus on the external environment as cause of the illness. The presentation is often polysymptomatic, and epidemic outbreaks may appear. The patients usually refuse alternative explanations of their symptoms and discredit and reject any suggestion of a psychogenic etiology. It is important to distinguish between hygienic problems and ESS problems, particularly when poor and inadequate hygienic factors are present simultaneously with an ESS epidemic.

Sick-building syndrome fatigue as a possible predation defense

Sick-building syndrome is an illness characterized by fatigue, headache, and upper-respiratory complaints. It is usually associated with modern office buildings, structures with an impervious outer shell and inoperable windows. Poor air quality, specific pollutants, and inadequate ventilation are considered common causes. The ability to smell faint odors requires air that is free of contamination. Human evolutionary ancestors depended on odors for survival. Even the slightest increase in the ability to smell a predator conveyed a distinct, immediate survival advantage. Conversely, an enormous survival advantage would also accrue to the animal that sought protection or avoided activity when this vital olfactory information was unavailable. Such would be the case with fire on the savannah. The foraging, olfactory dependent animal, unable to smell predators because of contaminated air, would be quickly snatched by a keen-sighted carnivore. There exist, however, well-described reflexes from the nose mediated through the trigeminal nerve that discourage activity when these free nerve endings are irritated. This mechanism may serve as a defense against predation. In adulterated atmosphere the animal, subdued by these reflexes, would be less likely to venture forth and, therefore, less vulnerable to predators. Similar reflexes may persist in humans, activated by poor air quality, air ill-suited for the dissemination of odors. I suggest that the human perception of these inhibitory reflexes is the feeling of fatigue associated with the sick building syndrome.

An epidemic of pneumococcal disease in an overcrowded, inadequately ventilated jail

BACKGROUND

In the United States many correctional facilities now operate at far over capacity, with the potential for living conditions that permit outbreaks of respiratory infections. We investigated an outbreak that was identified in an overcrowded Houston jail after two inmates died of pneumococcal sepsis on the same day. Outbreaks of pneumococcal disease have been rare in the era of antibiotics.

METHODS

We assessed risk factors for pneumococcal disease in both a case-control and a cohort study. Ventilation was evaluated by measuring carbon dioxide levels and air flow to the living areas of the jail. The extent of asymptomatic infection was determined by culturing pharyngeal specimens from a random sample of inmates. Type-specific immunity was determined with an enzyme immunoassay.

RESULTS

Over a four-week period, 46 inmates had either acute pneumonia or invasive pneumococcal disease due to Streptococcus pneumoniae serotype 12F. The jail's capacity had been set at 3500 inmates, but it housed 6700 at the time of the outbreak; the inmates had a median living area of only 34 ft2 (3.2 m2) (interquartile range, 28 to 56 ft2 [2.6 to 5.2 m2]) per person. There were significantly fewer cases of disease among inmates with 80 ft2 (7.4 m2) per person or more (P = 0.030). Carbon dioxide levels ranged from 1100 to 2500 ppm (acceptable, < 1000), and the ventilation system delivered a median of only 6.1 ft3 of outside air per minute per person (interquartile range, 4.4 to 8.5 ft3; recommended, > or = 20 ft3). The attack rate was highest among inmates in cells with the highest carbon dioxide levels and the lowest volume of outside air delivered by the ventilation system (relative risk, 1.94; 95 percent confidence interval, 1.08 to 3.48). Of underlying medical conditions, intravenous drug use was most strongly associated with disease (odds ratio, 4.50). The epidemic strain (serotype 12F) was cultured from 7 percent of the asymptomatic inmates. Of 11 case patients tested with the enzyme immunoassay, 9 (82 percent) lacked preexisting immunity to this strain.

CONCLUSIONS

Severe overcrowding, inadequate ventilation, and altered host susceptibility all contributed to this outbreak of pneumococcal disease in a large urban jail.

Air recirculation and sick building syndrome: a blinded crossover trial

OBJECTIVE

This study tested the hypothesis that recirculated air in mechanically ventilated buildings causes symptoms commonly referred to as the sick building syndrome and perceptions of poor indoor air quality.

METHODS

A blinded, four-period crossover trial was carried out in two identical buildings, contrasting 70% return air (index phase) with 0% of return air (reference phase). Each period lasted 1 work-week. The study population comprised 75 workers who had reported symptoms related to the work environment or perceptions of poor indoor air quality. Participants reported their ratings of symptoms, their perceptions, and related information in a daily diary. The outcome criteria included aggregative symptom scores for mucosal irritation, skin reaction, allergic reaction, and general symptoms formed of ratings of component symptoms. Perceptions of unpleasant odor, stuffiness, or dustiness were additional outcome criteria.

RESULTS

All 75 participants returned their diaries. For no symptoms did the scores differ between the two phases more than could be expected by chance. Mean rating of unpleasant odor was significantly smaller during the index phase, but mean ratings of dustiness and stuffiness did not differ materially between the two phases.

CONCLUSIONS

Our results suggest that 70% recirculated air, when accompanied by an adequate intake of outdoor air, can be used without causing adverse effects.