If you’re planning a chess game indoors, or any activity that requires mental concentration, it may be a good idea to open up a window. Researchers used computer models to analyze the quality of indoor chess games and found that even with a slight increase in air pollution, the likelihood that players would make a mistake increased by 2.1%, and the severity of the errors rose by 10.8%.

A team at the Maastricht University School of Business and Economics in the Netherlands analyzed over 30,000 moves by 121 players through three tournaments in Germany in 2017, 2018, and 2019, each of which lasted two months. Pollution levels were measured during these competitions. The researchers then compared the moves against the optimal ones determined by a chess engine.

“We find that when individuals are exposed to higher levels of air pollution, they make more mistakes, and they make larger mistakes,” study co-author Juan Palacios said in a statement. “Against comparable opponents in the same tournament round, being exposed to different levels of air quality makes a difference for move quality and decision quality.”

Air pollution and decision making

Previous studies have reported the negative impacts of air pollution on cognition and brain health. Long-term exposure to air pollution is linked to brain damage, while acute exposure can lead to neuro-inflammation and brain oxidative stress. Once cognitive performance is affected, strategic decision-making is also believed to suffer. However, evidence for this is lacking.

Chess offers the perfect setting to evaluate how air pollution affects skilled individuals making strategic decisions, the researchers argued. This is because there’s an overlap in the skills needed in chess and those in strategic decision-making. Deciding on a move in chess is a complex cognitive task, which requires intuition, perception, and problem-solving skills.

For their study, the researchers set up air quality sensors in the tournament venues and measured carbon dioxide, fine particulate matter (PM2.5), and temperature. As each tournament lasted eight weeks, players faced different air conditions. PM2.5 concentrations variated from 14 to 70 micrograms per cubic meter of air – levels found in most US cities.

They compared the player’s actual moves with the ones generated by the chess engine and observed the dip in performance. After ruling out other possible explanations, such as noise or temperature change, they found air pollution was the reason behind the dip. Chess players even performed more poorly when facing time constraints and higher air pollution.

“There are more and more papers showing that there is a cost with air pollution, and there is a cost for more and more people,” Palacios said. “And this is just one example showing that even for these very [excellent] chess players, who think they can beat everything — well, it seems that with air pollution, they have an enemy who harms them.”

The researchers believe their study’s findings could have strong implications for high-skilled office workers, who could also be faced with difficult cognitive tasks in conditions of changing air pollution. For Palacios, the overall objective was to give “accurate estimates to policymakers who are making difficult decisions about cleaning up the environment.”

The study was published in the journal Management Science.