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Humans are a prominent source of airborne biological particles in occupied indoor spaces, but few studies have quantified human bioaerosol emissions. The chamber investigation reported here employs a fluorescencebased technique to evaluate bioaerosols with high temporal and particle size resolution. In a 75-m 3 chamber, occupant emission rates of coarse (2.5-10 lm) fluorescent biological aerosol particles (FBAPs) under seated, simulated officework conditions averaged 0.9 AE 0.3 million particles per person-h. Walking was associated with a 5-69 increase in the emission rate. During both walking and sitting, 60-70% or more of emissions originated from the floor. The increase in emissions during walking (vs. while sitting) was mainly attributable to release of particles from the floor; the associated increased vigor of upper body movements also contributed. Clothing, or its frictional interaction with human skin, was demonstrated to be a source of coarse particles, and especially of the highly fluorescent fraction. Emission rates of FBAPs previously reported for lecture classes were well bounded by the experimental results obtained in this chamber study. In both settings, the size distribution of occupant FBAP emissions had a dominant mode in the 3-5 lm diameter range. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Practical ImplicationsBiological particles, including skin squames and microbes, are ubiquitous in indoor air and constitute a substantial portion of coarse airborne particulate matter. Human emissions of fluorescent biological particles as measured in this chamber study were strongly associated with the vigor of activities. More than two-thirds of the emissions, on average, originated from the floor even when occupants were seated. Overall, results were quantitatively consistent with previously reported findings from observational monitoring in a university classroom. This study adds quantitative information to the emerging body of evidence that human occupancy contributes meaningfully to indoor bioaerosol levels.

Human occupants are an important source of microbes in indoor environments. In this study, we used DNA sequencing of filter samples to assess the fungal and bacterial composition of air in an environmental chamber under different levels of occupancy, activity, and exposed or covered carpeting. In this office-like, mechanically ventilated environment, results showed a strong influence of outdoor-derived particles, with the indoor microbial composition tracking that of outdoor air for the 2-hour sampling periods. The number of occupants and their activity played a significant but smaller role influencing the composition of indoor bioaerosols. Human-associated taxa were observed but were not particularly abundant, except in the case of one fungus that appeared to be transported into the chamber on the clothing of a study participant. Overall, this study revealed a smaller signature of human body-associated taxa than had been expected based on recent studies of indoor microbiomes, suggesting that occupants may not exert a strong influence on bioaerosol microbial composition in a space that, like many offices, is well ventilated with air that is moderately filtered and moderately occupied.

This study examined the effects of personally controlled air movement on human thermal comfort and perceived air quality (PAQ) in warm-humid environments. At temperatures 26, 28, and 30°C, and relative humidity (RH) 60% and 80%, sixteen human subjects were exposed to personally controlled air movement provided by floor fans in an environmental chamber. The subjects reported their thermal sensation, thermal comfort, and PAQ during the tests. Two breaks periods with elevated metabolic levels were used to simulate normal office activities. Results show that with personally controlled air movement, thermal comfort could be maintained up to 30°C and 60% RH, and acceptable PAQ could be maintained up to 30°C 80% RH, without discomfort from humidity, air movement or eye-dryness. Thermal comfort and PAQ were resumed within 5 minutes after the breaks. The 80% acceptable limit implicit in comfort standards could be extended to 30°C and 60% RH. The average energy consumed by the fans for maintaining comfort was lower than 10W per person, making air movement a very energy-efficient way to deliver comfort in warm-humid environments.

A novel heated/cooled chair was evaluated for its effect on thermal sensation and comfort.The chair is exceptionally efficient, allowing standalone battery operation over long periods.Its capabilities at providing comfort needed to be established.Twenty-three college students participated in 69 2.25-hour tests. Four heated/cooled chairs were placed in an environmental chamber resembling an office environment. The chamber temperatures were 16°C, 18°C and 29°C. During the tests the subjects had full control of the chair power through a knob located on the chair. The heated/cooled-chair results could be compared to those of conventional mesh and cushion chairs tested in the same three environmental conditions in a previous study, as well as to a thermoelectrically heated and cooled chair.Subjective responses for thermal sensation and comfort were obtained at 15-minute intervals. The results show that the heated/cooled chair strongly influences the subjects' thermal sensation and improves thermal comfort and perceived air quality. No significant differences were found between men and women. The chair provided comfortable conditions for 92% of the subjects in a range of temperatures from 18°C to 29°C.