High on traffic

Posted on November 29, 2011


Dateline: 10 November 2011 // Posted by: Deirdre Metcalf
Source: Daily Mail

Story: “Car fumes are a mild narcotic that help us cope with city stress, claims scientist”

Summary: Carbon monoxide (CO) is well known as an odorless, poisonous gas that is fatal to humans.  However, a recent study by Professor Itzhak Schnell of Tel Aviv University in Israel claims that low levels of CO can actually help people cope with the stresses associated with living in cities.

In the study, thirty-six healthy individuals spent two days in Tel Aviv, which is the busiest city in Israel.  Four environmental stress sources were measured: temperature, noise pollution, CO levels, and the impact of crowds.  The participants reported the extent of their stress.  In addition, their heart rate and pollutant levels were measured.

Professor Schnell found that noise pollution was the most significant cause of stress for the participants.  The levels of CO were much lower than the researchers predicted, and the presence of the CO gas appeared to have a narcotic effect on the participants.  Schnell claims that CO counteracted the stress that the participants experienced in the city.

Why is this PseudoNews? The negative effects of carbon monoxide are very well-known.  The fact that CO poisoning is the most common cause of fatal poisoning in Britain today (according to the article, fifty people in the UK die each year from inhaling CO) makes it seem implausible that CO could be beneficial for one’s health.

The article gives very little detail about how CO was measured, so it is unclear how the reduction in stress levels can be caused by the presence of CO gas.  In addition, only four environmental factors were measured in this study.  The environment of Tel Aviv or any other large city has so many confounding variables that were not controlled for in this study.  It is impossible to control for all of the variables that exist in an urban environment in a study like this.  The only way to determine the role of CO in reducing one’s stress would be to control all other factors by conducting this study in a laboratory environment, rather than the chaotic urban environment of Tel Aviv.

What features of pseudoscience are on show? Firstly, the conclusions of this study are influenced by confirmation bias.  The environment is a very controversial topic as seen in many media reports on global warming and pollution, and these conclusions confirm one of the beliefs that the conditions of the environment are fine and that society does not need to make any changes to the status quo.  This case confirms the belief that society does not need to lower the amount of CO pollution in our environment.

Secondly, this study has vagueness in measurement.  The methods for measuring the amount of CO gas in the participant’s environment are not explained.  We do not know how CO levels were measured or how often they were measured.  Without this crucial information, it cannot be determined if the conclusions were actually supported by the data.

Finally, this research study avoids falsifiability.  The stress levels of the participants are measured by self-report.  This type of anecdotal evidence relies on the informants themselves and can never be verified.  Humans are fallible, and self-report data can be affected by memory, biases, and many other facts of life.  The conclusions rely on the self-reported stress levels, so if the data are not falsifiable, neither are the conclusions.

The moral of the story: Carbon monoxide should still be considered very dangerous, and pseudoscientific reports such as this should not be used to inform policy decisions regarding the safety of poisonous gases in our environment.