Human personal air pollution clouds in a naturally ventilated office during the COVID-19 pandemic.

Personal cloud, termed as the difference in air pollutant concentrations between breathing zone and room sites, represents the bias in approximating personal inhalation exposure that is linked to accuracy of health risk assessment. This study performed a two-week field experiment in a naturally ventilated office during the COVID-19 pandemic to assess occupants' exposure to common air pollutants and to determine factors contributing to the personal cloud effect. During occupied periods, indoor average concentrations of endotoxin (0.09 EU/m3), TVOC (231 µg/m3), CO2 (630 ppm), and PM10 (14 µg/m3) were below the recommended limits, except for formaldehyde (58 µg/m3). Personal exposure concentrations, however, were significantly different from, and mostly higher than, concentrations measured at room stationary sampling sites. Although three participants shared the same office, their personal air pollution clouds were mutually distinct. The mean personal cloud magnitude ranged within 0-0.05 EU/m3, 35-192 µg/m3, 32-120 ppm, and 4-9 µg/m3 for endotoxin, TVOC, CO2, and PM10, respectively, and was independent from room concentrations. The use of hand sanitizer was strongly associated with an elevated personal cloud of endotoxin and alcohol-based VOCs. Reduced occupancy density in the office resulted in more pronounced personal CO2 clouds. The representativeness of room stationary sampling for capturing dynamic personal exposures was as low as 28% and 5% for CO2 and PM10, respectively. The findings of our study highlight the necessity of considering the personal cloud effect when assessing personal exposure in offices.

Indoor air quality investigation before and after relocation to WELL-certified office buildings

Air pollutant exposure in workplace environments has been associated with health and cognitive outcomes of workers. While green building certification programs have been instrumental in promoting indoor air quality (IAQ), the present literature indicates inconsistent evidence. Recent emergence and proliferation of WELL certification program that prioritizes human health has evoked new questions about its effectiveness in relation to IAQ. To investigate the effectiveness of the WELL certification, we have quantitatively compared IAQ results before and after relocation to two WELL-certified office buildings using the same cohort of occupants. Physical measures included integrated samples of TVOC, individual VOC, formaldehyde and acetaldehyde, NO2, SO2, O3 and longitudinal records of CO2 and size-resolved particles. Complementary survey responses about satisfaction with IAQ and thermal comfort were collected from ~250 employees. For the majority of air pollutants, there was no significant concentration difference between non-WELL and WELL buildings, but not always. The WELL-certified buildings had substantially higher levels of TVOC and individual VOC associated with paints, especially shortly after the relocation. However, there was statistically significant improvement in IAQ satisfaction after relocation into WELL buildings regardless of the air pollution levels, possibly confounded by thermal environment, awareness of the WELL certification or other non-measurable factors.

Occupant satisfaction with indoor environmental quality, sick building syndrome (SBS) symptoms and self-reported productivity before and after relocation into WELL-certified office buildings

Recent green building certification programs have put a strong emphasis on occupant health and well-being. For recently emerged WELL certification, we lack evidence about its effectiveness in relation to occupant satisfaction, productivity and health. Here, we compared the results of occupant satisfaction with the indoor environmental quality (IEQ) obtained from the same cohort of employees who transitioned from three non-WELL (two BREEAM and one conventional) to three WELL-certified office buildings. For two out of three building pairs, we found a statistically significant increase in building and workspace satisfaction after relocation to WELL buildings. However, for 55 % of compared cases, there was insignificant difference as the result of relocation. The positive effect of WELL certification was evident for parameters such as building cleanliness and furniture, but there was no difference in satisfaction with noise and visual comfort. Relocation from BREEAM to WELL buildings had insignificant effect on satisfaction with IEQ, except for air quality in one case. Regardless of the certification label, buildings usually did not attain the 80 % standard satisfaction threshold. The satisfaction scores did not alter during the first year of working in WELL buildings. We also observed that the level of certification did not scale with the overall building satisfaction scores. Comparisons between the occurrence of Sick Building Syndrome (SBS) symptoms and self-reported productivity scores revealed insignificant differences between WELL and non-WELL buildings, except for symptom of tiredness that was lower in WELL buildings. The effect of Covid-19 measures interfered with the self-reported work abilities of 78 % of occupants.