Wednesday, November 02, 2005

General Building Ventilation Which Meets Standards Causes Illness

Brooklyn Dodger found a nice paper in a nice new journal, while trailing references. Harvard School of Public Health spent a lot of time around Polaroid, one of the original high tech companies from the first wave of the university business alliance [the abstract spilt the beans.]Outdoor air supply was most important in reducing sick leave. Cost of sick leave associated with air supply in compliance with ASHRAE was about $400 per employee. Another example of inadequate standards.


Risk of sick leave associated with outdoor air supply rate, humidification, and occupant complaints.

Milton, D. K.; Glencross, P. M., and Walters, M. D.

Indoor Air. 2000 Dec; 10(4):212-21.

Abstract: We analyzed 1994 sick leave for 3,720 hourly employees of a large Massachusetts manufacturer, in 40 buildings with 115 independently ventilated work areas. Corporate records identified building characteristics and IEQ complaints. We rated ventilation as moderate (approximately 25 cfm/person, 12 ls-1) or high (approximately 50 cfm/person, 24 ls-1) outdoor air supply based on knowledge of ventilation systems and CO2 measurements on a subset of work areas, and used Poisson regression to analyze sick leave controlled for age, gender, seniority, hours of non-illness absence, shift, ethnicity, crowding, and type of job (office, technical, or manufacturing worker). We found consistent associations of increased sick leave with lower levels of outdoor air supply and IEQ complaints. Among office workers, the relative risk for short-term sick leave was 1.53 (95% confidence 1.22-1.92) with lower ventilation, and 1.52 (1.18-1.97) in areas with IEQ complaints. The effect of ventilation was independent of IEQ complaints and among those exposed to lower outdoor air supply rates the attributable risk of short-term sick leave was 35%. The cost of sick leave attributable to ventilation at current recommended rates was estimated as $480 per employee per year at Polaroid. These findings suggest that net savings of $400 per employee per year may be obtained with increased ventilation. Thus, currently recommended levels of outdoor air supply may be associated with significant morbidity, and lost productivity on a national scale could be as much as $22.8 billion per year. Additional studies of IEQ impacts on productivity and sick leave, and the mechanisms underlying the apparent association are needed.

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