Diesel Fumes Are As Bad for Your Well-Being As Your Partner Dying: Study

Diesel exhaust pipes
The exhaust system of a Volkswagen Passat TDI diesel car is seen in Esquibien, France, on September 23, 2015. Diesel cars produced significant amounts of nitrogen oxides. Mal Langsdon/Reuters

Harmful fumes produced largely by diesel vehicles can be as damaging for people's well-being as the death of a partner, according to a study.

The study, entitled "Can Clean Air Make You Happy?" and first published in March, found that nitrogen dioxide could have a "substantive" impact on life satisfaction and human well-being.

Nitrogen dioxide occurs naturally through environmental processes including lightning, but the vast majority is produced by the combustion of fossil fuels. Diesel vehicles produce far greater quantities of nitrogen dioxide than non-diesel modes of transport.

The study, carried out by researchers at the University of York in northern England, measured the impact of nitrogen dioxide levels on subjective life satisfaction. The researchers used well-being data from the British Household Panel Survey and the U.K. Household Longitudinal Survey and compared it against air pollution levels as measured by the British government.

The researchers said it was the first study to analyze the relationship between nitrogen dioxide levels and life satisfaction, taking in account other factors such as socioeconomic status that could otherwise sway the findings. Respondents were asked to rate their life satisfaction on a scale from "completely unsatisfied" to "completely satisfied."

Around 3 million premature deaths were caused around the world in 2012 by ambient air pollution—which includes nitrogen oxides, the group of gases to which nitrogen dioxide belongs—according to the World Health Organization. The U.K. has one of the highest rates of death due to nitrogen dioxide pollution in Europe.

The study found a "significant and negative association" between average nitrogen dioxide levels and life satisfaction, and said the impact was "comparable to many 'big-hitting' life events." For example, the researchers determined that the negative effect on well-being of high nitrogen dioxide levels was roughly equivalent to half the impact caused by an employed person losing their job. Furthermore, the impact of the gas was comparable to a person losing their marital partner through separation or widowhood.

"Given that the effect of [nitrogen dioxide] is, to some extent, experienced by everyone (i.e. not everyone is unemployed but everyone is subject to a certain level of [nitrogen dioxide] exposure), this suggests that the welfare gains to society from reductions in exposure can be substantive," said the study.

Read more: Air pollution causes 7 million deaths per year

The highest nitrogen dioxide levels in the U.K. occur in London, with the lowest being recorded in southwest England. With 11,490 premature deaths related to nitrogen dioxide levels in 2013, the U.K. is second only to Italy in feeling the impact of the gas, according to a 2016 report by the European Environment Agency. The report also found that London's Marylebone Road had the highest levels of the gas in Europe.

The vast majority of modern diesel cars emit way more nitrogen oxides than is permitted by official limits, according to a 2016 dataset published by Emissions Analytics. A January report by the International Council for Clean Transportation found that diesel cars emit 10 times more nitrogen oxides per liter of fuel than diesel heavy-duty trucks and buses, which are subjected to far more stringent testing than smaller vehicles.

Nitrogen oxides were at the center of the Volkswagen emissions scandal in 2015, when the German manufacturer was found to have cheated emissions testers by equipping its vehicles with software that enabled them to emit less toxic fumes when being tested than in real-life conditions. But campaigners say that not enough has been done to combat car emissions cheating since the scandal, and the European Commission began legal action against the U.K. and six other European Union states in December 2016 for failing to tackle the problem.

The gases are damaging to the respiratory system and can lead to the development of conditions, such as asthma, after prolonged exposure.