Environment International, Vol. 17, pp. 371-378, 1991 0160-4120/91 $3.00 + .00 Printed in the U.S.A. All rights reserved. Copyright © 1991 Pergamon Press plc INDOOR AIR QUALITY REQUIREMENTS FOR HEALTHY OFFICE BUILDINGS: RECOMMENDATIONS BASED ON AN EPIDEMIOLOGIC STUDY Jouni J.K. Jaakkola Department of Environmental Hygiene and Toxicology, National Public Health Institute, and Laboratory of Heating, Ventilating and Air Conditioning, Helsinki University of Technology, Finland Leena M. Reinikainen National Public Health Institute, Finland Olli P. Heinonen Department of Public Health, University of Helsinki, Helsinki, Finland Antti Majanen and Olli Seppgmen Laboratory of Heating, Ventilating and Air Conditioning, Helsinki University of Technology, Finland E1 9003-034M (Received 19 March 1990; accepted 10 December 1990) Indoor air quality requirements for healthy (healthful) office buildings in Nordic climate are presented based on the results of an epidemiological study. The study was performed in the Pasila Office Center, a modern eight-story building with 2150 office workers, located in Helsinki. The results of the study concerning the indoor air quality and health are summarized, and recommen- dations and their limitations are discussed. The following indoor air quality requirements are made for healthy (healthful) office buildings: (1) The recommended room temperature is 21 + 2°C, (2) individual control of the room temperature is desirable, (3) relative humidity should exceed 20% in all conditions, (4) the minimum airflow rate for good ventilation is 10 L/s .per- sons, (5) windows should be openable to give extra individual control of the environment, and (6) involuntary exposure to environmental tobacco smoke should be avoided. INTRODUCTION The design and construction of healthy office build- ings has become a major challenge for building designers and constructors due to the increased num- ber of symptoms and environmental complaints ex- pressed by office workers. The problem of indoor air Correspondence and request for reprints to: Dr. J.J.K. Jaakkola, National Public Health Institute, K1/Ko 302, Otakaari 4 A, SF-02150 Espoo, Finland. pollution in office buildings has increased in two ways: new sources of potentially hazardous indoor air pollutants, such as building materials and office equipment, have been introduced continuously and the reduced ventilation rates after the energy crisis have increased the accumulation of pollutants in in- door air. Often the cause of the symptoms and complaints has not been found in spite of thorough measure- ments of indoor air, although the occupants have often blamed the poor indoor air quality and the 371