Carbon monoxide is an odorless gas emitted by car exhausts and generators. It is also a byproduct of incomplete combustion of several other fuels including coal, oil, natural gas and wood. Elevated levels are toxic to humans and animals, with symptoms of poisoning including headaches, nausea, dizziness, fatigue and confusion. Israeli researchers have discovered that inhaling small amounts of carbon monoxide (CO), an odorless, poisonous gas, may help reduce the stress of urban life.

Published in the journal Environmental Monitoring and Assessment by lead researcher Professor Itzhak Schnell of Tel Aviv University and colleagues, the research explains the surprising phenomena scientists uncovered in examining the effect of environmental stressors on the human body.

The Effects Of Carbon Monoxide On Mental Health

In conducting their study, scientists evaluated the biological changes of 36 healthy participants aged 20 to 40, as they spent two days exploring bustling centers and busy streets within the city of Tel Aviv, a dense urban city replete with buses, traffic, pedestrians, malls and outdoor shopping centers. The subjects were asked to shop, walk in busy areas, and use public transportation as part of the experiment.

Using portable sensors, researchers monitored reactions to temperature changes, noise pollution, carbon monoxide levels, and crowds, referred to as social load. Heart rate monitors and pollution levels were measured as well, along with participants' self-reported data ranking the stress levels of their various experiences during the trial period. The study was conducted during all four seasons to assess the impact of climate variations on urban dwellers.

Much to the surprise of the researchers, the gas levels inhaled by the participants measured at 1-15 parts per million every half hour, far lower than expected. Yet, despite such low gas inhalation levels, the impact of carbon monoxide seemed to have a narcotic effect on the subjects' stress levels, with the gas presence apparently neutralizing the negative psychological effects of noise pollution and crowds.

Urban Living Proves Not-So Stressful

Furthermore, noise pollution from human voices emerged as the greatest source of environmental discomfort, with participant feedback revealing the most significant amount of stress occurring in traditionally crowded areas, such as indoor and outdoor shopping malls and main thoroughfares. The level of distress accumulated through working hours, but carbon monoxide levels seemed to improve the coping skills that enabled the participants to experience diminishing stress later in the day.

Study authors suggest their findings indicate that urban living may not be as dangerous as previously considered. The fact that the participants did not display any permanent or lasting effects from consistent exposure to the gas further validates this suggestion.

The next step in the research will entail analyzing the impact of environmental stressors on more vulnerable residents. Those would include infants, senior citizens and those suffering from respiratory conditions including asthma.

In the meantime, scientists recommend alleviating urban stress by controlling noise pollution caused by humans. With the average decibel level in the test city measured at 85 dB, turning down the volume in human speech alone could have an immediate effect on reducing stress in fellow urban dwellers, according to the scientists.

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