A longitudinal study of ventilation rates in California office buildings and self-reported occupant outcomes including respiratory illness absence

Abstract

a b s t r a c tBackground: Limited evidence has associated lower ventilation rates (VRs) in offices with higher illnessrelated absence rates. Methods: We studied spaces in office buildings, selected without knowledge of their VRs, in three California climate zones. In each study space, real-time logging sensors measured carbon dioxide and thermal parameters for one year. Web-based surveys every three months collected data on occupants' health outcomes. Using multivariate models, relationships were assessed between CO 2 concentrations, or VRs estimated from CO 2 , and adverse occupant outcomes including respiratory infections and illness absences. For all outcomes, positive associations were hypothesized with higher CO 2 levels (and negative associations with higher VRs). Results: Low survey response limited sample size and study power. In the 16 study spaces, CO 2 concentrations were uniformly low over the year, and most estimated VRs ranged from twice to nine times the California office minimum VR standard (7 L/s or 15 cfm per person). Primary CO 2 and VR metrics had no statistically significant relationships with occupant outcomes. Conclusions: Within the observed range of uniformly low CO 2 and high VRs (mostly 16e42 L/s per person), little variation in contaminant concentrations would be expected, which would explain lack of relationships with occupant outcomes. These high VRs resulted partly from frequently used energysaving "economizer" cycles in moderate California climates, but VRs at other times also substantially exceeded required VRs. These findings suggest, consistent with theory, that within a higher VR range, increased VRs do not reduce respiratory illness. Further studies are needed to better characterize such relationships.

Alternative ventilation strategies in U.S. offices: Saving energy while enhancing work performance, reducing absenteeism, and considering outdoor pollutant exposure tradeoffs

“…The total VR year , which includes the contribution of infiltration, was much higher, particularly in the small-CAV office. As a result, CO 2 concentrations were lower than one would expect at the design mechanical VR (~950 ppm), but consistent with the low levels observed in many real U.S. offices both with and without economizers [67,68,86]. Energy outcomes were highly consistent with reported sector-wide consumption and costs, as detailed in the companion article [40].…”

“…SBS symptoms have been linked with lower ventilation in a number of studies [6,8,58,68]. The relation is assumed to be related to ventilation's role in diluting indoor-generated air pollutants whose presence chemically or physically stresses some occupants, but exact mechanisms, pathways, sensory irritant species, and contributing factors are not well understood [8,58,69].…”

“…IAQ public health impacts (outcome category 3) are defined herein as society-wide risks whose costs are unlikely to be perceptible by a building-related decision-maker. There are many potential health risks related to indoor air, but few are certain and well-characterized enough to evaluate in the context of venti-lation decisions [68]. For example, volatile organic compounds (VOC) are too variable in strength and composition and too uncertain in health impact [20,[70][71][72] (although some of their shorter-term effects may be at least partially captured by the empirical relations for profitable impacts).…”

RETRACTED: Simulation and Analysis of Various Ventilation Systems Given in an Example in the Same School of Indoor Air Quality

“…The quality of internal air is one of the factors that affect the pace and quality of knowledge acquisition. Therefore, it is important that classrooms have high quality of air [1][2][3][4][5].…”

Self-reported mould and long-term sickness absences from work

“…In addition to health, the extant literature shows that poor indoor environmental quality is linked to increased sickness absences from work, which has a further negative impact on productivity [4–8]. The primary focus of the literature has been attentive to the relationship between poor ventilation and absence [5, 8].…”