NOx: Traffic Dramatically Underestimated as Major Polluter

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In metropolitan areas throughout Europe maximum permissible values of nitrogen oxide are consistently breached. It has been a challenge to determine how much each polluter contributes to the emission output. Until now emission levels were mainly calculated by collecting emission data at laboratory testing facilities and subsequently extrapolating them in models. However, the amount of pollutant emissions that vehicles emit on a daily basis depends on numerous factors, for example on individual driving behavior. The recent Diesel scandal showed, for example, that measurements at engine test stands based on the New European Driving Cycle (NEDC) or similar emission testing procedures can be highly uncertain for predicting actual environmental impacts. A large number of new studies have recently been published suggesting that emission levels from test stands have to be adjusted upwards.

In metropolitan areas throughout Europe maximum permissible values of nitrogen oxide are consistently breached. It has been a challenge to determine how much each polluter contributes to the emission output. Until now emission levels were mainly calculated by collecting emission data at laboratory testing facilities and subsequently extrapolating them in models. However, the amount of pollutant emissions that vehicles emit on a daily basis depends on numerous factors, for example on individual driving behavior. The recent Diesel scandal showed, for example, that measurements at engine test stands based on the New European Driving Cycle (NEDC) or similar emission testing procedures can be highly uncertain for predicting actual environmental impacts. A large number of new studies have recently been published suggesting that emission levels from test stands have to be adjusted upwards.

Environmental protection and health agencies base their air pollution management on atmospheric models that rely on these experimental data from test facilities. While there have been some doubts about nitrogen oxide emissions for some time, scientists lacked the technology to measure the actual amount of emitted pollutants in a specific area and to determine their overall source strength. A team of physicists headed by Thomas Karl from the Institute of Atmospheric and Cryospheric Sciences at the University of Innsbruck has now implemented a process to do exactly that in the center of Innsbruck, Austria.   

Read more at University of Innsbruck

Image: Thomas Karl is from the Institute of Atmospheric and Cryospheric Sciences at the University of Innsbruck. (Credit: Uni Innsbruck)