Survey and Critical Review of the Literature on Indoor Air Quality, Ventilation and Health Symptoms in Schools
A survey and critical review were undertaken of existing published literature and reports on indoor air quality (IAQ), ventilation, and IAQ- and building-related health problems in schools, including California schools. Over 450 relevant publications were obtained and reviewed, including papers published in the archival peer-reviewed scientific literature, proceedings of scientific meetings, government reports, 77 NIOSH Health Hazard Evaluation Reports (HHER) and 70 reports on investigations of problem schools in California. Most of the reviewed literature was for complaint or problem schools. The types of health symptoms reported in schools were very similar those defined as "sick building syndrome" (SBS) symptoms, although this may be due, at least in part, to the type of health symptom questionnaires used. Some of the symptoms, e.g., wheezing, are indicative of asthma. In the studies in which complaint and noncomplaint buildings or areas were compared, complaint buildings generally had higher rates of health symptoms. Formaldehyde, total VOCs, CO and microbiological pollutants were the most commonly measured air pollutants in schools. Most of the formaldehyde measurements made in the US. were made in complaint schools but were generally below 0.05 ppm. Measurements of other pollutants were too limited to make conclusions as to the prevalence of indoor concentrations above levels of concern, even in problem schools. However, there is some evidence indicating that microbiological pollutants may be of particular concern. The few scientific studies on causes of symptoms in complaint schools indicate that exposures to molds and to allergens in schools contribute to asthma, SBS and other respiratory symptoms. Other indoor air pollutants, such as VOCs, aldehydes, etc., have been investigated to only a very limited extent, although there are reasons to suspect they may also contribute to health symptom prevalences in schools. The maj or building-related problem identified was "inadequate ventilation with outside air." Several lines of evidence indicate that inadequate ventilation with outside air is a fairly common problem in schools in general, including those in California. However, "inadequate ventilation" can only be considered an indicator, not the causal agent(s) for health symptoms reported in problem schools. Waterdamage to the building shells of schools, leading in turn to mold contamination and growth, was the second most frequently reported building-related problem. The root causes of many of the ventilation and water-damage problems in the schools was inadequate and/or deferred maintenance of school buildings and WAC systems. However, in most studies, neither the building and ventilation systems problems nor specific pollutants have been clearly and unambiguously demonstrated to be causally related to the symptoms. Although there is now considerable qualitative information on health complaints, ventilation and IAQ problems in complaint schools, we do not know what fraction of schools is experiencing IAQ and ventilation problems, and related health symptoms. There is also a lack of scientifically rigorous and quantitative information on the causal relationships between health symptoms, exposure, and dose response relationships that are needed to establish health standards for the protection of children in schools. Finally, the effectiveness and the costs and benefits of various remedial actions, undertaken to solve problems in specific schools, remain largely unknown. Recommendations to address these issues are made in this report.