With multiple logistic regression analysis, handling CCP weekly or daily had a significant effect on mucosal irritation (odds ratio [OR]=1.3, 95% confidence interval [CI]=1.1–1.6), and handling CCP was the only exposure with a significant effect on general symptoms (see above; OR=1.6, 95% CI=1.1–1.7). Also the authors commented that these office workers handled relatively small quantities of CCP.
Zweers et al. 1992. Zweers et al. [1992] conducted a cross-sectional epidemiologic study of indoor air quality and health effects in the Netherlands. Approximately 10,500 workers in 61 office buildings were studied. CCP usage, which was not the primary focus of the study, was ascertained in a questionnaire and analyzed as a dichotomous variable—handling "more than zero CCP per day" versus handling "zero." No usage prevalence was reported. Multivariate logistic regression models adjusted for personal variables, type of air-handling system, and various job and workspace variables. Controlling for some variables in the multivariate models (e.g., allergic or respiratory symptoms) may have underestimated actual CCP effects, as these factors may themselves have resulted from CCP exposures. Despite these limitations, the authors found associations of CCP handling with oronasal symptoms (OR=1.18, 95% CI=1.00–1.39), perception of air contaminants (OR=1.48, 95% CI=1.15–1.89), air quality complaints (OR=1.21, 95% CI=1.05–1.40), and lighting complaints (OR=1.30, 95% CI=1.12–1.51).
Mendell 1991 and Fiske et al. 1993. Mendell [1991] and Fiske et al. [1993] conducted a cross-sectional epidemiologic study in Northern California among 880 office workers in 12 office buildings. A strength of this study, unlike previous studies, was that the study facilities were selected without regard to worker complaints. Work-related symptoms used in the analyses were defined as those that "occurred often or always in the last year and improved when away from work." The questionnaire response rate was 85%. A number of factors (including CCP) were associated with the prevalence of work-related symptoms after adjustment in a logistic regression model for personal, psychosocial, job, workspace, and building factors (Table 4–4). The OR was not increased for a set of control symptoms included to detect overreporting associated with risk factors of possible concern (such as air-conditioning or CCP). In multivariate analyses adjusted for other workplace exposures, the authors reported that the use of CCP for more than 1 hr/day was associated with increased ORs for the following: eye, nose, and throat symptoms (OR=1.6, 95% CI=1.0–2.6); chest tightness or difficult breathing (OR=2.3, 95% CI=1.1–4.9); and fatigue or sleepiness (OR=2.1, 95% CI=1.3–3.5).
Omland et al. 1993. See Section 4.2.3.2 for a discussion of this study.
Jaakkola and Jaakkola 1999. Jaakkola and Jaakkola [1999] conducted a cross-sectional epidemiologic study of office workers in 41 randomly selected buildings in Helsinki in 1991. They used a questionnaire to investigate associations of health effects with work involving CCP, photocopying, and VDT use. The populations studied had not been selected on the basis of prior complaints or concerns about CCP. The response rate to the questionnaire was 81%, representing a study population of 2,678 (1,119 men and 1,559 women). Of these workers, 910 were exposed to CCP. The outcomes studied included the work-related symptoms often associated with sick building syndrome as well as chronic respiratory symptoms and respiratory infections. Multivariate analyses controlled for building ventilation type in addition to a number of demographic, psychosocial, and other environmental factors. Blinding to the specific study hypotheses reduced the likelihood of information bias in reporting exposure. Known confounders
