Large amounts of CO toxic; tiny amounts may calm urbanites

Health Scan: Center aims to rehabilitate walking abilities of people with brain damage due to trauma; J'lem cancer patients can surf net.

November 27, 2011 06:59
4 minute read.
Pedestrians crossing a city street [illustrative]

Pedestrians crossing street 311. (photo credit: Thinkstock/Imagebank)

Ironically, a large amount of the tasteless, colorless, odorless and highly toxic gas CO (carbon monoxide) has been found – in very small doses – to be beneficial in alleviating “environmental stress” in humans. Prof. Itzhak Schnell of Tel Aviv University’s department of geography and the human environment has discovered that low levels of CO – which is called a “silent killer” because it can poison the nervous system and heart – can have a narcotic effect that helps city dwellers cope with high noise levels. But don’t try this at home!

Published recently in the journal Environmental Monitoring and Assessment, the discovery was made in the context of a wider project designed to study the impact of environmental stressors on the human body. Most environmental observation stations, explains Schnell, are located outside stressful city centers, where pollutants such as vehicular and human traffic are significantly lower. This results in distorted data.

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But 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 and 40 to spend two days in Tel Aviv.

The test subjects traveled by public or private transportation or by foot to busy thoroughfares, restaurants, malls and markets. Researchers monitored the impact of four different environmental stressors – temperature; noise pollution; carbon monoxide levels; and crowds.

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

The most surprising find of the study, says Schnell, involved the 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 one to 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.

Thus, living in a major city might not have as negative a health impact as the researchers were expecting, they suggested.

Though participants exhibited rising stress levels throughout the day, CO had a mitigating influence, and extended exposure to the chemical had no lasting effects. The study’s next step is to investigate how environmental loads impact the more vulnerable segments of the population, such as infants, the elderly and those with medical conditions such as asthma. “We would be able to tell more accurately under what conditions vulnerable people shouldn’t go out and, more importantly, identify areas that are still safe, helping to increase freedom of movement,” notes Schnell.

But for now, urban dwellers can all contribute to making their surroundings less stressful by turning down the noise, he suggests. The findings indicate that most of the noise in an urban landscape is generated by human activity, and if individuals made an effort to reduce the noise they were making, they could help to reduce the environmental load placed on their neighbors.


A unique institute for walking rehabilitation, called Reuth-Step of Mind, was recently launched at Tel Aviv’s non-profit Reuth Medical-Rehabilitation Center. Established in collaboration with Step of Mind Ltd., it aims to rehabilitate the walking abilities of people with brain damage due to trauma, surgery, stroke and/or cerebral palsy and those among the elderly who have fallen and injured themselves.

Special shoes called ReStep constitute part of a computerized system; Training with the shoes is based on research involving motor learning, brain flexibility and walking rehabilitation. The system uses software personally adapted to each patient’s walking ability. During the training, brain centers responsible for walking are activated and the angle of the sole changes, challenging the patient to react in real time, maintain his balance and improve his walking. Treatment is provided by an expert physiotherapist, under the supervision of a physician specializing in physical medicine and rehabilitation and includes 22 sessions of 45 minutes each.

The Reuth center’s director, Dr. Nissim Ohana, noted: “This innovative technology adds significant value to rehabilitative treatment. The new institute blends in well with our goal: to retain our leading position in the field of rehabilitation, both nationally and globally.”


Hundreds of cancer patients at Jerusalem’s Shaare Zedek Medical Center are now able to connect to wireless Internet while undergoing chemotherapy treatment and surf the Net, send e-mails and connect to social networks. The Yad Tamar La’holeh voluntary organization, which focuses on helping cancer patients, teamed up with Intel on a pilot program to lend laptops to people who periodically spend hours in the oncology day hospital. Now time flies much more pleasantly for patients whose worries are at least temporarily forgotten.

Patients report that since they have been able to work on the computers, they feel much calmer; the nurses and doctors there also feel much less pressured. The free service will expand to three other hospitals in the pilot program.

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