Rising Outdoor CO2 Levels Harming Life Indoors

Feeling less mentally sharp at your job? The reason could be as simple as the 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.

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.

"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."

"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.