The potential for large benefits of improved IEQ had been predicted a decade or more ago. In a 1989 report to congress, the U.S. Environmental Protection Agency estimated that the annual cost of cancer and heart disease from indoor air pollutants was $6 billion and that the annual cost of productivity reductions from indoor air pollution was $60 billion . Based on analyses performed in the late 1990s, the financial benefits of improved IEQ were estimated to be $6 to $14 billion from reduced respiratory disease, $1 to $4 billion from reduced allergies and asthma, $10 to $30 billion from reduced sick building syndrome symptoms, and $20 to $160 billion from direct productivity gains unrelated to health [31, 32]. The more current estimates of benefits summarized in this web site take advantage of the large body of new research since the 1990s and also take advantage of several statistical analyses of research findings that have resulted in quantitative relationships between IEQ parameters and health effects or work performance. The new estimates also have a more narrow scope, focusing on estimates of the benefits of specific IEQ improvement measures for which the highest quality data are available. Where there is an overlap between the new and older estimates, the projections are, in most cases, broadly consistent. The current estimated $1 billion in annual benefits from reducing asthma by reducing dampness and mold in homes overlaps with the prior $1 to $4 billion estimate of benefits of reduced allergies and asthma from implementation of a broader range of IEQ improvement measures. The current estimated annual value of work performance gains just in U.S. offices are $7 to $15 billion from increasing ventilation rates and adding economizers (see Figures 1 and 2) and $2 billion from avoiding high temperatures in the winter (see Figure 3). These numbers are broadly consistent with the prior estimate of annual productivity gains of $20 to $160 billion possible from implementing a broader range of IEQ improvement measures in the full U.S. workforce. The current estimated annual benefit associated with reduced SBS symptoms is on the order of $1 billion (Figure 3), which is substantially smaller than the $10 to $30 billion range given previously for reduced SBS symptoms. However, the older estimate of benefits accounted for the impact of SBS symptoms on work performance, while the current estimate accounted only for the health costs associated with SBS symptoms. In summary, if one accounts for differences in scope, there is a broad agreement between the current and prior estimates of the benefits of improving IEQ in U.S. buildings.