Paris report: Temperature increases cause more diesel emissions

While it has long been known that emissions of greenhouse gasses like CO2 and NOx contribute significantly to rising global temperatures, research conducted in Paris has shown that rising temperatures can have a similar effect on emissions. The research has been conducted by The Real Urban Emissions (TRUE) Initiative, a partnership between the FIA Foundation and the International Council on Clean Transport organised to analyse real-world emissions data and raise awareness about vehicle emissions.

TRUE’s report has shown that NOx emissions from Euro 6 diesel cars in Paris are 4.8 times higher than those of Euro 6 petrol cars, and these diesel emissions are sensitive to driving conditions and ambient temperature. According to the research, NOx emissions tended to increase due to increasing vehicle specific power, and temperatures above 30°C. Euro 5 and Euro 6 diesel cars showed 20 to 30 per cent higher levels of emissions at temperatures above this level, compared with emissions at temperatures between 20°C and 30°C. TRUE has estimated that Euro 5 and Euro 6 diesel cars were responsible for 63 per cent of total passenger vehicle NOx emissions in Paris.

Despite these figures, TRUE’s report indicates some improvement. For example, City buses and coaches have shown emission improvements, with newer Euro VI buses emitting between 59 and 84 per cent less greenhouse gasses than older Euro V buses. Particulate matter emissions from diesel cars have also shown significant decreases. CO and NOx emissions from moped and motorcycles have also decreased, though total emissions from these vehicles are still high relative to other vehicle types in the same emission classification category Crit’Air 1, including Euro 5 and Euro 6 petrol cars.

Due to the analysis, TRUE suggests that the French Government follow through on its promise to ban all diesel cars in the Parisian centre by 2024, despite rising pressure to relax these restrictions. The report also suggests that more research must be conducted as global temperatures continue to change, and that only low and zero-emission vehicles should be allowed in the Parisian centre.

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