Science Current Events | Science News | Brightsurf.com
 

Elevated Indoor Carbon Dioxide Impairs Decision-Making Performance

October 18, 2012
Overturning decades of conventional wisdom, researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have found that moderately high indoor concentrations of carbon dioxide (CO2) can significantly impair people's decision-making performance. The results were unexpected and may have particular implications for schools and other spaces with high occupant density.

"In our field we have always had a dogma that CO2 itself, at the levels we find in buildings, is just not important and doesn't have any direct impacts on people," said Berkeley Lab scientist William Fisk, a co-author of the study, which was published in Environmental Health Perspectives online last month. "So these results, which were quite unambiguous, were surprising." The study was conducted with researchers from State University of New York (SUNY) Upstate Medical University.

On nine scales of decision-making performance, test subjects showed significant reductions on six of the scales at CO2 levels of 1,000 parts per million (ppm) and large reductions on seven of the scales at 2,500 ppm. The most dramatic declines in performance, in which subjects were rated as "dysfunctional," were for taking initiative and thinking strategically. "Previous studies have looked at 10,000 ppm, 20,000 ppm; that's the level at which scientists thought effects started," said Berkeley Lab scientist Mark Mendell, also a co-author of the study. "That's why these findings are so startling."

While the results need to be replicated in a larger study, they point to possible economic consequences of pursuing energy efficient buildings without regard to occupants. "As there's a drive for increasing energy efficiency, there's a push for making buildings tighter and less expensive to run," said Mendell. "There's some risk that, in that process, adverse effects on occupants will be ignored. One way to make sure occupants get the attention they deserve is to point out adverse economic impacts of poor indoor air quality. If people can't think or perform as well, that could obviously have adverse economic impacts."

The primary source of indoor CO2 is humans. While typical outdoor concentrations are around 380 ppm, indoor concentrations can go up to several thousand ppm. Higher indoor CO2 concentrations relative to outdoors are due to low rates of ventilation, which are often driven by the need to reduce energy consumption. In the real world, CO2 concentrations in office buildings normally don't exceed 1,000 ppm, except in meeting rooms, when groups of people gather for extended periods of time.

In classrooms, concentrations frequently exceed 1,000 ppm and occasionally exceed 3,000 ppm. CO2 at these levels has been assumed to indicate poor ventilation, with increased exposure to other indoor pollutants of potential concern, but the CO2 itself at these levels has not been a source of concern. Federal guidelines set a maximum occupational exposure limit at 5,000 ppm as a time-weighted average for an eight-hour workday.

Fisk decided to test the conventional wisdom on indoor CO2 after coming across two small Hungarian studies reporting that exposures between 2,000 and 5,000 ppm may have adverse impacts on some human activities.

Fisk, Mendell, and their colleagues, including Usha Satish at SUNY Upstate Medical University, assessed CO2 exposure at three concentrations: 600, 1,000 and 2,500 ppm. They recruited 24 participants, mostly college students, who were studied in groups of four in a small office-like chamber for 2.5 hours for each of the three conditions. Ultrapure CO2 was injected into the air supply and mixing was ensured, while all other factors, such as temperature, humidity, and ventilation rate, were kept constant. The sessions for each person took place on a single day, with one-hour breaks between sessions.

Although the sample size was small, the results were unmistakable. "The stronger the effect you have, the fewer subjects you need to see it," Fisk said. "Our effect was so big, even with a small number of people, it was a very clear effect."

Another novel aspect of this study was the test used to assess decision-making performance, the Strategic Management Simulation (SMS) test, developed by SUNY. In most studies of how indoor air quality affects people, test subjects are given simple tasks to perform, such as adding a column of numbers or proofreading text. "It's hard to know how those indicators translate in the real world," said Fisk. "The SMS measures a higher level of cognitive performance, so I wanted to get that into our field of research."

The SMS has been used most commonly to assess effects on cognitive function, such as by drugs, pharmaceuticals or brain injury, and as a training tool for executives. The test gives scenarios-for example, you're the manager of an organization when a crisis hits, what do you do?-and scores participants in nine areas. "It looks at a number of dimensions, such as how proactive you are, how focused you are, or how you search for and use information," said Fisk. "The test has been validated through other means, and they've shown that for executives it is predictive of future income and job level."

Data from elementary school classrooms has found CO2 concentrations frequently near or above the levels in the Berkeley Lab study. Although their study tested only decision making and not learning, Fisk and Mendell say it is possible that students could be disadvantaged in poorly ventilated classrooms, or in rooms in which a large number of people are gathered to take a test. "We cannot rule out impacts on learning," their report says.

The next step for the Berkeley Lab researchers is to reproduce and expand upon their findings. "Our first goal is to replicate this study because it's so important and would have such large implications," said Fisk. "We need a larger sample and additional tests of human work performance. We also want to include an expert who can assess what's going on physiologically."

Until then, they say it's too early to make any recommendations for office workers or building managers. "Assuming it's replicated, it has implications for the standards we set for minimum ventilation rates for buildings," Fisk said. "People who are employers who want to get the most of their workforce would want to pay attention to this."

Funding for this study was provided by SUNY and the state of New York.

Lawrence Berkeley National Laboratory


Related Carbon Dioxide Current Events and Carbon Dioxide News Articles


Meteorites Yield Clues to Red Planet's Early Atmosphere
Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks.

Stanford scientists develop 'playbook' for reverse engineering tissue
Consider the marvel of the embryo. It begins as a glob of identical cells that change shape and function as they multiply to become the cells of our lungs, muscles, nerves and all the other specialized tissues of the body.

Stanford biologists help solve fungi mysteries
A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate change.

Ancient sea-levels give new clues on ice ages
International researchers, led by the Australian National University (ANU), have developed a new way to determine sea-level changes and deep-sea temperature variability over the past 5.3 million years.

Biologists Develop Nanosensors to Visualize Movements and Distribution of Plant Stress Hormone
Biologists at UC San Diego have succeeded in visualizing the movement within plants of a key hormone responsible for growth and resistance to drought.

Relieving electric vehicle range anxiety with improved batteries
Electric vehicles could travel farther and more renewable energy could be stored with lithium-sulfur batteries that use a unique powdery nanomaterial.

Warm US West, cold East: A 4,000-year pattern
Last winter's curvy jet stream pattern brought mild temperatures to western North America and harsh cold to the East.

Pioneering findings on the dual role of carbon dioxide in photosynthesis
Researchers at Umeå University have found that carbon dioxide, in its ionic form bicarbonate, has a regulating function in the splitting of water in photosynthesis.

Greenland ice cores show industrial record of acid rain, success of US Clean Air Act
The rise and fall of acid rain is a global experiment whose results are preserved in the geologic record.

Odds that global warming is due to natural factors: Slim to none
An analysis of temperature data since 1500 all but rules out the possibility that global warming in the industrial era is just a natural fluctuation in the earth's climate, according to a new study by McGill University physics professor Shaun Lovejoy.
More Carbon Dioxide Current Events and Carbon Dioxide News Articles

The Carbon Dioxide Syndrome

The Carbon Dioxide Syndrome
by Jennifer Stark and Russell Stark (Author)


Learn why changing your breathing can improve your health and well-being through the Butekyo Method. This method will help those with sleep disorders, panic attacks, allergies, hypertension and asthma.

Carbon Democracy: Political Power in the Age of Oil

Carbon Democracy: Political Power in the Age of Oil
by Timothy Mitchell (Author)


Does oil wealth lead to political poverty? It often looks that way, but Carbon Democracy tells a more complex story. In this magisterial study, Timothy Mitchell rethinks the history of energy, bringing into his grasp as he does so environmental politics, the struggle for democracy, and the place of the Middle East in the modern world. 

With the rise of coal power, the producers who oversaw its production acquired the ability to shut down energy systems, a threat they used to build the first mass democracies. Oil offered the West an alternative, and with it came a new form of politics. Oil created a denatured political life whose central object – the economy – appeared capable of infinite growth. What followed was a Western democracy dependent on an undemocratic Middle East....

Carbon Dioxide as Chemical Feedstock

Carbon Dioxide as Chemical Feedstock
by Michele Aresta (Editor)


Filling the need for an up-to-date handbook, this ready reference closely investigates the use of CO2 for ureas, enzymes, carbamates, and isocyanates, as well as its use as a solvent, in electrochemistry, biomass utilization and much more.
Edited by an internationally renowned and experienced researcher, this is a comprehensive source for every synthetic chemist in academia and industry.


Porous Materials for Carbon Dioxide Capture (Green Chemistry and Sustainable Technology)

Porous Materials for Carbon Dioxide Capture (Green Chemistry and Sustainable Technology)
by An-Hui Lu (Editor), Sheng Dai (Editor)


This multi-authored book provides a comprehensive overview of the latest developments in porous CO2 capture materials, including ionic liquid–derived carbonaceous adsorbents, porous carbons, metal-organic frameworks, porous aromatic frameworks, micro porous organic polymers. It also reviews the sorption techniques such as cyclic uptake and desorption reactions and membrane separations. In each category, the design and fabrication, the comprehensive characterization, the evaluation of CO2 sorption/separation and the sorption/degradation mechanism are highlighted. In addition, the advantages and remaining challenges as well as future perspectives for each porous material are covered.This book is aimed at scientists and graduate students in such fields as separation, carbon, polymer,...

Green Carbon Dioxide: Advances in CO2 Utilization

Green Carbon Dioxide: Advances in CO2 Utilization
by Gabriele Centi (Editor), Siglinda Perathoner (Editor)


PROMISING NEW APPROACHES TO RECYCLE CARBON DIOXIDE AND REDUCE EMISSIONSWith this book as their guide, readers will learn a variety of new approaches and methods to recycle and reuse carbon dioxide (CO2) in order to produce green fuels and chemicals and, at the same time, minimize CO2 emissions. The authors demonstrate how to convert CO2 into a broad range of essential products by using alternative green energy sources, such as solar, wind, and hydro-power as well as sustainable energy sources. Readers will discover that CO2 can be a driving force for the sustainable future of both the chemical industry and the energy and fuels industry.Green Carbon Dioxide features a team of expert authors, offering perspectives on the latest breakthroughs in CO2 recycling from Asia, Europe, and North...

Natural Extracts Using Supercritical Carbon Dioxide

Natural Extracts Using Supercritical Carbon Dioxide
by Mamata Mukhopadhyay (Author)


Synthesizing research from a wide variety of sources, this work offers a convenient guide to a clean, safe, inexpensive, non-toxic, non-polluting solvent that performs better than most conventional solvents. Natural Extracts Using Supercritical Carbon Dioxide reviews recent development in the technology and its applications to the food, flavor, fragrance, and pharmaceutical industries. It outlines the many advantages the method has over traditional methods like steam distillation, solvent extraction, and molecular distillation and it supports the popular trend toward the use of natural products in these industries.



Carbon Dioxide Capture and Storage

Carbon Dioxide Capture and Storage
by United Nations (Author)


This IPCC Special Report describes sources, capture, transport, and storage of CO2. It discusses the costs, economic potential, and societal issues of the technology, including public perception and regulatory aspects. Storage options evaluated include geological storage, ocean storage, and mineral carbonation. The report places CO2 capture and storage in the context of other climate change mitigation options. The volume includes a Summary for Policymakers approved by governments represented in the IPCC, and a Technical Summary. It provides invaluable information for researchers in environmental science, geology, engineering and the oil and gas sector, policy-makers in governments and environmental organizations, and scientists and engineers in industry.

Carbon Dioxide Angiography: Principles, Techniques, and Practices

Carbon Dioxide Angiography: Principles, Techniques, and Practices
by Kyung Cho (Editor), Irvin F. Hawkins (Editor)


With an abundance of illustrations and tables to highlight critical information, this source provides a practical approach to the use of CO2 as a contrast agent for diagnostic angiography, vascular intervention, and other interventional procedures in both adults and pediatrics. Clearly laying-out key points in the science, technique, and clinical applications of this procedure, this source will be a constant companion for physicians treating various disorders affecting arterial and venous circulation.

CARBON DIOXIDE SEQUESTRATION INTO DEEP SALINE AQUIFERS: ASSESSMENT OF DIFFUSIVE AND CONVECTIVE MECHANISMS DURING CARBON DIOXIDE SEQUESTRATION INTO DEEP SALINE AQUIFERS

CARBON DIOXIDE SEQUESTRATION INTO DEEP SALINE AQUIFERS: ASSESSMENT OF DIFFUSIVE AND CONVECTIVE MECHANISMS DURING CARBON DIOXIDE SEQUESTRATION INTO DEEP SALINE AQUIFERS
by Emre Özgür (Author)


The analytical and numerical modeling of CO2 sequestration in deep saline aquifers having different properties was studied with diffusion and convection mechanisms. The complete dissolution of CO2 in the aquifer by diffusion took thousands, even millions of years. In diffusion dominated system, an aquifer with 100 m thickness saturated with CO2 after 10,000,000 years. It was much earlier in convective dominant system. In diffusion process, the dissolution of CO2 in aquifer increased with porosity increase; however, in convection dominant process dissolution of CO2 in aquifer decreased with porosity increase. The increase in permeability accelerated the dissolution of CO2 in aquifer significantly, which was due to increasing velocity. The results of convective dominant...

Carbon Dioxide Recovery and Utilization

Carbon Dioxide Recovery and Utilization
by M. Aresta (Editor)


Carbon Dioxide Recovery and Utilization is a complete and informative resource on the carbon dioxide sources and market at the European Union level, with reference to the world situation. The book covers the following themes: - Sources of carbon dioxide and their purity,
- Market of carbon dioxide and its uses,
- Separation techniques of carbon dioxide from flue gases,
- Analysis of the potential of each technique and application,
- Basic science and technology of supercritical CO2,
- Reactions in supercritical CO2 and its use as reactive solvent,
- Utilization of CO2 in the synthesis of chemicals with low energy input,
- Conversion of CO2 into fuels: existing techniques,
- Dry reforming of methane,
- Assessment of the use of carbon dioxide for the...

© 2014 BrightSurf.com