Expert Voices

Rising Outdoor CO2 Levels Harming Life Indoors (Op-Ed)

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Marlene Cimons is a Washington based freelance writer who specializes in science, health and the environment. Her work frequently appears in, among others, the Washington Post, Microbe Magazine, and Climate Progress. She also writes for Climate Nexus, a nonprofit that aims to tell the climate story in innovative ways that raise awareness of, dispel misinformation about and showcase solutions to climate change and energy issues in the United States. She contributed this article to Live Science's Expert Voices: Op-Ed & Insights.

If you've been feeling less mentally sharp at your job lately, it may not be the result of aging or sleep deprivation, or any number of other frequent complaints one hears from workers in today's fast-paced society. The reason could be as simple as the indoor office air you breathe. 

Carbon dioxide, once regarded as a harmless indoor air pollutant, can seriously impair peoples' cognitive ability and decision-making, according to the results of a new public health study that raises important implications for climate policy, as well as for the health of workers, schoolchildren and others routinely exposed to poor air quality in the workplace, schools, airplanes and in the home.

Moreover, it will become more difficult to correct the indoor dangers by increasing ventilation from the outside if atmospheric carbon dioxide levels continue to rise as a result of global warming, the researchers said.

The study was published online in Environmental Health Perspectives, a journal of the National Institute of Environmental Health Sciences.

"We can now add potential adverse effects on human cognitive function to a long list of public health reasons why we need to act on climate to prevent carbon dioxide concentrations from increasing,'' said Joseph Allen, assistant professor of exposure assessment science at the Harvard T.H. Chan School of Public health and lead author of the study. [Humans Spew More Carbon Dioxide than All of Earth's Volcanoes ]

The researchers, from Harvard T.H. Chan School of Public Health, SUNY Upstate Medical and Syracuse University, found that cognitive-function test scores among office workers doubled for those working in green buildings with enhanced ventilation when compared to results from those same people working in environments simulating conventional office buildings with higher levels of carbon dioxide and other pollutants. Carbon dioxide also had significant, independent effects on cognitive function scores.

As carbon dioxide concentrations continue to surge outdoors, "this increases the potential for direct impacts on human cognitive function, and it also makes it more difficult for us to successfully ventilate our indoor environments to acceptable levels," Allen said. "Along with the indirect impacts that carbon dioxide has on human health through its role in causing climate change, our study suggests that carbon dioxide has significant direct impacts on human cognitive function at levels typically encountered indoors." 

The study supports an earlier 2012 study, also published in Environmental Health Perspectives, conducted by the U.S. Department of Energy's Lawrence Berkeley National Laboratory that found similar results. 

"The impacts of carbon dioxide on anthropogenic [human-caused] climate change are well understood, but our findings on carbon dioxide, and those from [the] previous study…are upending previous notions that carbon dioxide concentrations are benign at levels we typically encounter indoors," Allen said. 

Air quality under the microscope

The health problems associated with indoor air conditions likely originated from efforts, beginning in the 1970s, to conserve energy and reduce its costs by constructing airtight and energy-efficient buildings, but one unintended result has been less ventilation and more indoor air pollutants. 

In the current study, the scientists tested workers' decision-making performance under different environmental conditions, including outdoor air ventilation rate, volatile organic compounds (VOCs) and carbon dioxide, independent of outdoor air ventilation rate. (VOCs are carbon-based chemicals such as acetone and formaldehyde that evaporate at room temperature, and are present in common materials and products in offices.) 

Twenty-four participants — architects, designers, programmers, engineers, creative marketing professionals and managers — spent six full workdays, from 9 a.m. to 5 p.m., in an environmentally controlled office space, blinded to test conditions, and each was exposed to the same conditions, although the conditions varied each day. 

On different days, they were exposed to indoor air quality conditions representative of conventional office buildings in the United States, with a high concentration of volatile organic compounds — similar to what many workers currently encounter — as well as to "green" office space conditions, with a low concentration of chemicals. 

Additionally, the scientists added exposures simulating a green building with a high outdoor air ventilation rate, which they called "green+." Finally, they carried out a set of experiments that specifically looked at the independent effects of artificially elevated carbon dioxide levels independent of ventilation. 

The participants underwent cognitive testing at each level of exposure using a tool known as the Strategic Management Simulation. 

"[This] is a technology that is used to evaluate decision-making and productivity," said Usha Satish, a professor of psychiatry and behavioral sciences at SUNY Upstate Medical University and a co-author of the study. "Participants are immersed in real-world scenarios and their responses to the information and challenges presented are captured."

Subjects use a computer interface to make decisions about situations that match real-world, day-to-day challenges, from relatively simple tasks to highly complex thought and action. The scores can predict real-world success as measured by income, job level, promotions and level in organizations — meaning, the assessment reveals the abilities needed both for routine daily activities as well as higher level decisions people make at home and work. 

On average, cognitive scores were 61 percent higher during the green building days and 101 percent higher on the green+ building days than on the conventional building day, according to the study. Participants scored higher on the green+ days than the green day in eight of nine test areas, resulting in a 25 percent increase in scores on average when outdoor air ventilation rates were increased. 

"The significance of these numbers lies in the fact that these critical learning and decision- making parameters impact our day-to-day lives and have a bearing on how productive we are in our work and home environments," Satish said.

For seven of the nine areas of productive decision-making, the average scores decreased at each higher level of carbon dioxide. Cognitive function scores were 15 percent lower for the moderate CO2 day — about 945 parts per million, or ppm, and 50 percent lower on the day with CO2 concentrations around 1,400 ppm than on the two green+ days, according to the study.

The study was designed to represent typical conditions observed in many buildings, and did not include extreme exposures or choose uncommon VOC sources. (The research team also included John D. Spengler, Akira Yamaguchi professor of health and human habitation, doctoral candidate Piers MacNaughton, project engineer Jose Vallarino, all of the Harvard T.H. Chan School of Public Health; and Suresh Santanam, associate professor of biomedical and chemical engineering at Syracuse University and associate director of the Syracuse University Center of Excellence.)

Clearing the air

"Parents and workers should take this very seriously," said Vivian Loftness, a professor of architecture at Carnegie Mellon University, who has studied environmental design for more than 30 years. "CO2 has been used as an indicator of serious changes in our outdoor (climate change) and indoor (poor ventilation) environments, but has not been considered a toxin for humans until this time."

If carbon dioxide is both an indicator and a toxin, "there are a number of actions we should take immediately," she said, including finding ways to increase outside air ventilation rates in occupied spaces "to keep indoor CO2 levels below 600 ppm, and make sure that the breathing air gets to each occupant." Moreover, society must find ways to "stop the increase in outdoor CO2 to keep it below 600 ppm." 

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Currently atmospheric CO2 is at about 400 ppm.

"For most of human evolution and modern history, carbon dioxide levels in the atmosphere were in a fairly narrow range of 180 to 280 ppm," said Joseph Romm, founding editor of Climate Progress and author of the book Climate Change: What Everyone Needs to Know (Oxford, 2015). "Also, during that time, most people spent most of their time outdoors or in enclosures that were not tightly sealed." 

Today, however "[in] the places where most people work and live, CO2 concentrations are considerably higher than outdoors," he added. 

Lessening indoor levels of carbon dioxide is achievable "by [adding] trees and greenspace, the great consumers of CO2, and massive energy conservation — insulation, shade, daylight, natural ventilation to minimize power plant demands," Loftness said, adding: "This study adds critical weight to these goals."

Dr. Jennifer Lowry, chief of the toxicology section of Children's Mercy Hospital in Kansas City, Missouri, and chairwoman of the American Academy of Pediatrics Council on Environmental Health, agreed that society must aim for a healthier built environment, "which can be done by something as simple as increasing plants in the workplace and improving ventilation," she said. "This study shows the effects of climate change on a much smaller scale," she added. 

Study author Allen said that aggressive approaches could address the problems the researchers found, and provide many benefits. "There are things we can do, right now, to enhance indoor environmental quality and benefit human health, well-being and productivity," he said. "This is all within reach."

Read more from Marlene Cimons on her Expert Voices landing page.

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

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