Prevention of IEQ-related absence: an intervention study.
Milton-DK; Rudnick-S; Wand-M; Muilenburg-M; Kantrowitz-W; Walters-M; Johnsonton-S
NIOSH 2002 Dec; :1-58
This project addressed the NORA priorities Indoor Environment and Intervention Effectiveness Research. We conducted a blinded experimental intervention study of the independent effects of outdoor air supply rates on absence rates, respiratory infections characterized by RT-PCR, and non-specific building-related symptoms among office workers at Polaroid Corporation. We found that buildings available for this study all had high or very high rates of outdoor air supply. Modulation of the outdoor air supply rates within this range had no effect on absence rates. However, even at these very high rates, reducing outdoor air supply rates was associated with increasing likelihood of detecting respiratory viruses in air. We also found that one worker was infected with a genetically identical virus as that found in the office air the same week - indicating that respiratory viruses are spread by the airborne route at work. To facilitate this work, we developed a new mathematical model to predict airborne infection risks using carbon dioxide measurements. The method is appropriate when buildings are not at steady state and when outdoor air supply rates are not constant. This model predicts that at the high to very high ventilation rates used in available buildings, person-to-person airborne spread of respiratory infections would be a very rare event. However, it also predicts that the threshold indoor CO2 concentration above which infections including the common cold and influenza will spread among building occupants is significantly lower than currently allowed by building codes and ASHRAE standards. This indicates that additional studies of airborne infection transmission in crowded work environments, and especially in schools, are needed.
Respiratory-system-disorders; Diseases; Airborne-dusts; Airborne-particles; Mathematical-models; Work-environment; Indoor-air-pollution; Pulmonary-system-disorders; Aerosols; Indoor-environmental-quality
Final Grant Report
Work Environment And Workforce: Indoor Environment
National Institute for Occupational Safety and Health
Harvard School of Public Health, Boston, Massachusetts