Carbon Dioxide, Particulates, and Subjective Human Responses in Office Buildings Without Histories of Indoor Air Quality Problems

Abstract

Indoor air quality (IAQ) complaints have steadily increased since 1973 when the Arab oil embargo forced building owners and operators to reduce energy costs in their buildings, in part by reducing indoor/outdoor air exchange rates. Carbon dioxide measurements are commonly used as an indicator of the amount of fresh air that is being introduced into a building. Particulate measurements have also been used in the evaluation of IAQ. The purpose of this study was to evaluate the relationship between carbon dioxide and particulate levels and subjective human responses in office buildings without previous or current indoor air quality problems. Carbon dioxide and particulates were measured in six separate ventilation zones with direct-reading instruments. Subjective human responses about environmental conditions and health symptoms were subsequently measured with a self-reporting questionnaire developed in Sweden. Relationships between environmental measurements and human responses were investigated using chi-square analysis. Although not statistically significant, response rates were higher for all questions about environmental conditions and health symptoms in the higher carbon dioxide exposure group. The same trend existed between particulate exposure groups, along with a statistically significant correlation between particulate exposure and headache. Associations also existed between gender and age and questionnaire responses. This study shows the usefulness of environmental measurements coupled with self-report measures in the evaluation of IAQ. Since the study was conducted in “healthy” buildings, it provides valuable baseline data useful when analyzing data collected in buildings with IAQ problems.