CO2 Guru
After graduating college in his native Poland, Pawel Wargocki traveled first to Denmark in 1991 met Professor P. Ole Fanger[i] at the Technical University of Denmark. At the time, he was interested in heating and heating systems. While in Denmark, he participated in the researchon fragrances for masking odorous pollutants. This raised his interest in IAQ which he continued to study after returning to Denmark in 1993 for a originally planned 4-month scholarship that has never ended; he has worked at the Technical University of Denmark ever since together with the group assembled by Fanger which form the International Centre for Indoor Environment and Energy. It is now anchored at the Department of Civil Engineering, one of the 19 departments at the University which is one of the largest technical school in Scandinavia with over 10,000 students, 1200 PhD students, nearly 5,000 staff and 5 affiliated companies. Pawel is an Associated Professor at the Centre.
Nuggets mined from today’s show:
As a PhD student, he was tasked with development of a Reference Exposure Gas, an artificial indoor air for research purposes. One of his artificial indoor air combinations had 22 components (volatile organic compounds) others had fewer constituents.
Areas of interest:
During his PhD he examined human responses to different exposure levels of pollutants in an attempt to define ventilation levels for individual pollutants: tobacco smoke, human bioeffluents, building materials. Now interested in methods and solutions to mitigate exposures, not by ventilation but also source control and air cleaning.
Another major interest that began during PhD and developed over the years was the impact of IAQ on cognitive performance, later also the impact of thermal environment on cognitive performance, both for adults (working environment, offices) and children (pupils in elementary schools). Recently interested in the effects of IAQ on sleep and next day performance.
Recent research focused on indoor CO2 and its effects on humans. Not outdoor climate change and CO2 emissions.Major indoor sources of CO2 are humans and their metabolism. Other than that CO2 can be a product in the industry (e.g. fermentation).
Research in the 18th century by Antoine Lavoisier[ii] (father of gaseous chemistry) who claimed that this is not a lack of oxygen but excess of CO2 to cause negative health effects indoors.
Research in the 19th century by Max Joseph von Petenkofer[iii] demonstrated that these are human bioeffluents that corrupt air and that CO2 is only an excellent marker of the pollution level but not pollutant itself. He proposed levels >1000 ppm of CO2 to be a marker of unacceptable indoor air quality; the marker is still used today. Apparently, he proposed >700 ppm for bedrooms.
Although these levels are unlikely to occur unless there is a CO2 source in the building, e.g large assembly of people in a poorly ventilated space. Toxic levels in occupation exposures are set at 5000 ppm CO2 (8-hour exposure) and 30,000 ppm is set as a ceiling value (15 min exposure max). The latter is never to be expected indoors and former under very specific situations is also very seldom.
It has been known that sailors on submarines may experience increased fragility of bones. They are continuously exposed to elevated CO2 levels (up to 10,000 in nuclear and below 30,000 ppm in snorkel submarines). Submarine crews, especially the officers are carefully selected and highly trained so they are supposed to deal with stress and stressors under especially battle conditions.
2012 paper- “Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance”[iv]. The Fisk, Mendell and Satish group studied the effects of pure CO2 on cognitive performance in a chamberwhere the dominant pollutant was pure CO2 added from the cylinder to the highly ventilated chamber in order to reduce the influence of other pollutants to a minimum. Three different CO2 levels were studied: 600 ppm, 1000 ppm and 2500 ppm. The battery with performance tests examining ability to take decisions was presented to subjects. The study showed a systematic reduction of performance with increased level of CO2 with statistically significant effects shown at 2500 ppm. Pawel was struck by how well the study was designed, straightforward and clear. The results could not be accidental as the sources of bias were very well controlled. The study was a consequence of the research presented in Hungarian journal showing that CO2 at 4000 ppm can reduce performance of proof-reading.
Harvard group with Joe Allen replicated the earlier study and extended it and published in 2015. The study was performed in normal office space in the Syracuse Center of Excellent facilities. Subjects were exposed for the whole working day whereas in earlier study only for few hours. Again, the researchers saw the systematic effects of increased CO2 on the ability to make decisions, so the results re-confirmed earlier work; the effects were seen at even lower levels than in the first study. Again, the experimental procedures and methodologies were excellent so the observed could not be explained by systematic bias and could be attributed to exposures.
Pawel received a small grant from Bjarne Saxhof Foundation, a local Danish foundation anchored at the University. He always wanted to repeat the Fisk, Mendell and Satish study. He setup the team including a PhD student from Jiao Tong University in Shanghai and performed the work on the effects of CO2 in the stainless-steel chamber at the Centre. They did not use the same battery of tasks but their own battery composed of office-like tasks and psychological tests. Humans were exposed to 1000 ppm CO2 and then increased to 3000 ppm. CO2 was dosed from a cylinder and the chamber highly ventilated. Subjects were also exposed to human bioeffluents and these CO2 levels. This was done by reducing ventilation in the chamber. Reference condition was 500 ppm of CO2 similar to the first work. Besides they measured subjective responses of humans rating air quality, dissatisfaction and the intensity of perceived acute health symptoms such as irritation, difficulty to concentrate, fatigue or sleepiness. Besides several measurements of physiological responses were made with heartbeat, biomarkers and saliva and exhaled levels of CO2. These additional measurements were made to find the clue on why CO2 or bioeffluents could cause negative effects on performance. To their surprise they could not observe the effects on performance during exposures to CO2. And neither there were any negative subjective responses seen. In contrary the exposure to bioeffluents (with CO2) caused responses which were particularly strong at 3000 ppm. They could not solve the mystery of why CO2 could cause the negative effects. They then decided to extend the levels of CO2 to close to 5000 ppm, which is an occupational limit, but again no negative effects on performance on their batteries of tests were seen.
The question of whether CO2 is a pollutant remains thus partially unanswered. Interestingly bioeffluents with CO2 produced effects indicating that the lack of effect is not due to lack of sensitivity of the selected experimental approach.
Feedback and questions on the papers:
· Why weren’t effects seen with pure CO2?
· Why weren’t the results the same as other groups?
· What is the weakness of the results?
· Are differences related to the methods of testing?
The battery examining decision making performance is used in medical studies such as substance addiction and substance impairment. Painters exposed to vapors while painting also were shown to have reduced performance on these tests. The question is how the results obtained from the battery depict actual cognitive performance of office workers. Verification would be needed as the magnitude of effects is very high.
The battery of tests is the main difference in the described studies so perhaps the effects seen are because of the method of testing. This needs elucidation in the future. Furthermore, people are nearly ever experienced to pure CO2 so perhaps there can be some unusual response of the body to this rare exposure. That is another potential explanation. The most likely is related to stress. Measuring decision making can be considered as stressful and demanding. High stress related with testing and stress produced by CO2 (Pawel’s results implied slightly higher stress during exposure to CO2 but not significantly) can be a “toxic” mixture that causes negative performance. Further work is needed to examine this in detail.
5 Quick Questions:
Does archival literature indicate that CO2is toxic?
Yes, but at the levels under one order of magnitude higher than typically occurring indoors.
Does CO2create risks for building occupants and if so why?
No, unless they perform demanding cognitive tasks. Why? Probably because of elevated stress level.
Should ventilation standards be changed based on the recent studies on the effects of CO2?
No, they show do show that CO2 is an excellent proxy for potential negative effects.
What about human bioeffluents?
They seem to be perceived at literally any level indoors. They produce the measurable changes in cognitive performance and symptoms but at the levels higher than usually recommended for ventilation of spaces. The effects occur because of negative psychological reactions and elevated stress.
Is CO2 a pollutant or merely an index for IAQ?
Merely an index for IAQ.
Closing Comments:
· Remember all CO2 studies are excellent research, we can debate and discuss the findings.
· Outdoors levels of CO2 are significantly increasing, now more than 400 ppm, 60 ppm increase in 30 years.
· Reducing emissions from building materials and furniture results in humans becoming the major source of indoor pollution. We need more research on pollutants from humans.
· Some cars have ventilated seats to remove pollutants, maybe we’ll soon see them in offices.
· Pawel is in a team commencing a study on the effects of elevated CO2 and bioeffluents on the sleep and next day performance of school age children. He hopes to be back in IAQ Radio to present the results next year.
Z-Man signing off
Trivia Question:
Name the first gas to be distinguished from ordinary air and the scientist who discovered it?
Answer:
Carbon dioxide and Jan van Helmont
[ii]Povl Ole Fanger (July 16, 1934 – September 20, 2006) was an expert in the field of thermal comfort and perception of indoor environments. He was a senior professor at the International Centre for Indoor Environment and Energy at the Technical University of Denmark.
[ii]https://en.wikipedia.org/wiki/Antoine_Lavoisier
[ii]https://en.wikipedia.org/wiki/Max_Joseph_von_Pettenkofer
[ii]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3548274/
