Shared office space and the risk of the common cold.

The common cold persists as a major economic and public health problem worldwide. Despite its long-established ubiquity, little is yet certain about the determinants of indoor environment in spreading of the infection, and even less about the role of indoor air quality as a mediator. The effect of sharing an office with one or more colleagues on the risk of the common cold was studied in a modern, mechanically ventilated, 8 story office building in central Helsinki. Data on respiratory infections and the relevant personal and environmental determinants were collected in a self-administered questionnaire (response rate 71.0%). The study population, one person from each office on floors 3 to 8, consisted of 893 workers, 493 males (49.2%) and 454 females (50.8%). In logistic regression analysis the adjusted odds ratio (OR) for more than two episodes of common cold during the past 12 months in subjects with one or more office colleagues vs those working alone was 1.35 (95% CI 1.00-1.82). Among all workers higher risk also emerged for those with young children (OR 1.46, 1.05-2.04) or a history of hay fever (OR 2.07, 1.47-2.92). Females (OR 1.25, 0.95-1.66) and all under 40 years of age (OR 1.15, 0.86-1.55) had non-significantly increased risk, while smokers did not differ essentially from non-smokers (OR 1.05, 0.76-1.42). The results suggest that sharing office space increases the risk of the common cold, although the primary mode of transmission-airborne, direct or indirect contact-remains controversial.