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Inhale car exhaust to cope with city life

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Cities are dirty, noisy warrens of closely-packed humans. Now scientists from Tel Aviv have gathered evidence that suggests we cope with the stresses of urban life by breathing carbon monoxide, an odorless poison gas found in car exhaust.

In small doses, carbon monoxide is a narcotic with a calming effect. Psychologist Itzhak Schnell and his colleagues at Tel Aviv University conducted a study that suggested people were inadvertently getting stoned on carbon monoxide — and that it was possibly the main reason the extreme noisiness of city life wasn't driving them insane. Apparently the cure for noise pollution is fossil fuel emissions.

In a release about the group's study, Tel Aviv University explains:

Schnell and his fellow researchers wanted to measure how people living in an urban environment confronted stressors in their daily lives. They asked 36 healthy individuals between the ages of 20 to 40 to spend two days in Tel Aviv, Israel's busiest city. The test subjects travelled various routes to sites such as busy streets, restaurants, malls and markets, by public and private transportation or by foot. Researchers monitored the impact of four different environmental stressors: thermal load (heat and cold), noise pollution, carbon monoxide levels, and social load (the impact of crowds).

Participants reported to what extent their experiences were stressful, and their input was corroborated with data taken from sensors that measured heart rate and pollutant levels. Noise pollution emerged as the most significant cause of stress.

The most surprising find of the study, says Prof. Schnell, was in looking at levels of CO that the participants inhaled during their time in the city. Not only were the levels much lower than the researchers predicted - approximately 1-15 parts per million every half hour - but the presence of the gas appeared to have a narcotic effect on the participants, counteracting the stress caused by noise and crowd density.


In some ways, the most interesting aspect of this study was the researchers' discovery that noise is the most intense stress on urban dwellers. This could be selection bias, since the study was only conducted in one city. At any rate, further research certainly needs to be done before the experiences of 36 people visiting Tel Aviv for a few weeks can be used to justify sniffing tailpipes to deal with gridlock and skyscraper construction.

Illustration by carla castagno via Shutterstock