On May 11, 2016, we presented a webinar, “Knowledge in the Air,” at the invitation of the U.S. EPA Indoor Environments Division. The webinar was attended by more than 800 people and generated discussion that continued beyond the allotted time. Unfortunately, we could not get to all of the questions that were submitted and EPA has informed us that they have received requests to view the webinar from those who could not originally attend. Here, we group the questions with similar content and provide written responses. And, because the webinar was not recorded, we have included a link to a video of a similar presentation we gave on the same topic several months prior (Video: Abu Dhabi, 2015; Slides: Harvard.SUNY.Syracuse.EPA-Webinar.05-11-2016.pdf).
We wish to thank the U.S. EPA for the opportunity to present and all of the attendees for their engagement on this research. The public health literature is rich with evidence on how we can optimize indoor environments for health, and our hope is that this research adds to that body of science. The ultimate goal is to be sure all of this research reaches practitioners so that we can impact the health of all people, everywhere.
Q: Was this study conducted in a LEED-Certified Building?
A: The study was conducted in the Syracuse Center for Excellence (CoE), which is a LEED platinum building. The Willis H. Carrier Total Indoor Environmental Quality (TIEQ) Lab located within the building is a flexible environment that allowed us to change environmental conditions to a high degree of precision.
Q: Green buildings often have operable windows and individual controls regarding ventilation. Was this a consideration in the study?
A: In order to control ventilation rates, the windows were kept shut for the duration of the study. The TIEQ lab is unique in that it has individual controls for both ventilation rate and temperature; however, to simulate typical office environments we did not provide this personalization to our participants. All participants were exposed to the same conditions on each day.
Q: It would be helpful to see a definition of “green” buildings for each of the studies. I see the connection to CO2 but what VOCs are being minimized?
A: In this study, the green building condition was defined to be an environment with low VOC concentrations and an outdoor ventilation rate of 20 cfm/person. Some green building certifications give credits if total VOCs are kept below 500 μg/m3, and this is the threshold we tested. The EPA Building and Assessment Survey and Evaluation, conducted in the 1990s, found average total VOC concentrations in conventional, non-problem buildings to be approximately 450 μg/m3.
Q: In your study, how did you address participants who were initially more sensitive to low level exposures?
A: In accordance with our Institutional Review Board, we excluded asthmatics and smokers from the study during recruitment; however, recruitment was open to sensitive participants as our sample population was designed to be representative of the general population of knowledge workers. We did not assess whether any of our participants considered themselves to be sensitive to air quality.
Q: Have you considered including some more conventional, widely used tests of cognitive function in future studies, rather than relying only on one type of performance assessment, in broadly extrapolating your conclusions?
A: Yes. We are exploring the use of other tools for assessing cognitive function in future studies. The tool we used in this study is one that allows us to identify impacts to high-order cognitive function while many other commonly used tests rely on simpler performance tasks.
Q: Work experience is a huge determinant of cognitive functioning and therefore productivity: Was the amount of work experience and time spent in the field of work controlled among the different subjects?
A: This study used a within-subject design: each participant acts as their own control so their cognitive function during any particular condition is being compared relative to their baseline ability. Our sample population had a mix of managerial, profession, technical and administrative employees designed to be representative of the general population of knowledge workers. We had participants spend the entire work day in the test office, and we standardized the start time of the day and time at which the tests were administered.
Q: Regarding the COGFXStudy: Was there any method for accounting for extraneous influence on the participants during time that they were not in the control facility (e.g. home, supermarket, freeway traffic, etc.)?
A: Participants filled out daily questionnaires that asked about relevant exposures while at home and wore a watch that tracked physiological indicators, exercise and sleep.
Q: What kind of tools did you use for cost-benefit analysis and financial analysis? Any tools for non-financial benefits that you can recommend?
A: We used the EPA power profiler and Greenhouse Gas Equivalency Calculator to determine the environmental impacts of increased ventilation. The benefits in terms of productivity were derived from the field study of green buildings and cognitive function and normative data on salaries for knowledge workers in the U.S.
Q: Do you or other entities have plans to recreate the study to add to the data pool?
A: This work builds on 30 years of literature investigating the impact of indoor environmental quality on productivity and health. Our coauthor Usha Satish has used the SMS simulations to test similar environmental exposures in collaboration with Lawrence Berkeley National Laboratory, and the results are consistent with our findings. We are currently building on these findings by studying cognitive function in a sample of high-performing buildings across the U.S.
Q: Is 24 participants a sufficient sample size for this study?
A: The study utilizes a repeated measures study design to increase statistical power, testing 24 participants repeated over six days. Power calculations prior to the study being performed indicated we were unlikely to encounter Type II error. For account for potential Type I error, we used a linear mixed effects regression model to model fixed and random effects, and our findings were statistically significant at the alpha=0.05 level. This information indicates that the study was sufficiently powered to see an effect if one existed, and the findings are extremely unlikely attributable to chance.
Q: Primary souce of indoor CO2 is occupants; co-concentrations of CO2 are many (e.g., 300) bioeffluents. How this this study account for the bioeffluent effect compared to “pure” CO2?
A: To isolate the impact of CO2 independent of ventilation, we added pure CO2 to the TIEQ lab during two of the conditions. Lower CO2 concentrations and increased ventilation both had impacts on cognitive function at the levels tested in our study.
Q: Did the study look into particle count into the space versus the air change rates, and how additional ventilation affected particle counts?
A: Particulate matter concentration were very low on each day and did not vary significantly between conditions; however, it is important to note that bringing in more outdoor air may be an issue in regions with poor outdoor air pollution or poor filtration.
Q: How do you accurately determine a building air exchange rate, or might it be more important to monitor and measure and record key indoor air parameters?
A: We used several different ASHRAE recommended procedures for measuring ventilation rates and air exchange rates in this study. Our team is developing automated algorithms for processing indoor environmental data to produce reliable estimates of air exchange rate and other key environmental parameters in real-time.
Q: What else can be done to improve indoor air quality other than increasing ventilation?
A: Source control is also critical to maintaining good indoor environmental quality. Purchasing low chemical furnishings and materials is one way to remove the sources of harmful chemicals from the indoor environment. Improving filtration by selecting air filters with a higher MERV rating is another way to remove particles from both indoor and outdoor sources.
Q: What methods are available for an individual to test the indoor air quality of his or her office space?
A: Affordable indoor environmental quality sensors are now available on the market and can provide a relatively decent indication of the performance of a space, particularly when partnered with data processing algorithms.
Q: Can you briefly describe or talk about your current wearable IEQ sensor capabilities and shortcomings? Is there an online resource that describes your wearable IEQ sensor capabilities?
A: In this study, we did not use personal air monitors but opted instead for measurements at the participants’ workspace. We did equip our participants with a watch to track several indicators of physiological function.