Does Pollution Lead to More Crime?

The health implications of over-exposure to poor air quality are well-documented. Indeed, the World Health Organisation estimate that over 90% of the global population are breathing dangerous levels of air quality on a regular basis and that the issue is responsible for seven million premature deaths each year.

Physically, air pollution is clearly terrible for us… but what about mentally? Spiritually? Morally? A new study from the Association for Psychological Medicine has established a link between air pollution and unethical behaviour, positing that heightened anxiety caused by exposure to dirty air may make people more likely to cheat, deceive and commit crimes.

Breaking new ground

Previous studies have found that air pollution can cause elevated levels of stress, which has been linked to behavioural problems in the children of pregnant women exposed to poor air quality. However, new research attempted to go further than ever before by linking air pollution to crime and other forms of unethical behaviour.

The study, published in Psychological Science, encompassed air quality and crime statistics from 9,360 American cities over a nine-year period. Data about six major pollutants (including carbon monoxide (CO), nitrogen dioxide (NO2), particulate matter (PM) and sulphur dioxide (SO2)) was cross-referenced against seven major crimes (including aggravated assault, murder and robbery).

The results showed that cities with poorer levels of air quality also showed higher crime rates. This conclusion held true even when the researchers accounted for variables in the equation, such as gender distribution, race distribution, poverty rate, unemployment rates, median age and several others.

Establishing causal links

While the initial data is promising, it does not establish that air quality influenced crime rates, or vice versa. Therefore, the researchers undertook several further investigations to try and establish a causal link between the two. In particular, the authors of the paper were interested to see whether even imagining air pollution could increase the likelihood of committing unethical acts.

In one experiment, 256 subjects were shown a photo of either a polluted or clean landscape, then asked to imagine walking around the scene. They were then encouraged to participate in a word association task, for which they would be paid if they got the answers correct. The researchers acknowledged a glitch in the system which would reveal the right answer, but asked participants not to exploit it. They then surreptitiously monitored how many people cheated.

In another experiment, participants were again shown photos of clean or dirty places, before being asked to write about that location. They were then tested on the ethicality of their behaviour in certain situations. Those who viewed the contaminated scene and expressed more anxiety in their descriptions were more prone to cheat.

Further study needed

The authors of the study have stressed that there may well be a host of other factors at play when it comes to ethical behaviour, and they also concede that imagining air pollution is not the same as experiencing it.

However, their research has certainly given one more reason to add to the increasingly lengthy list on why we must improve air quality and reduce transport-related pollution, especially in an urban setting.