Combustion engines: high emissions from short commutes a huge challenge

Drivers in the U.S. have longer commutes than those in Europe and Asia, on average.

In the U.K., short commutes in vehicles with combustion engines—whether gasoline or diesel—pose particularly tough emission problems.

That’s because the exhaust aftertreatment systems have to warm up fully before they cut emissions to the levels required under EU regulations.

The problem has been highlighted by the British consultancy Emission Analytics, which routinely analyzes the data from its various EQUA Index sectors to highlight different emission statistics and challenges.

The company’s trenchant analyses of real-world emission and fuel-consumption data has gotten considerable attention, and it has now expanded into the U.S. as well.

This week, it noted that according to British government data, the average distance of a car journey in inner London was just 1.5 miles.

Portable Emissions Measurement Systems (PEMS) on a Peugeot 308

The implications of that figure, as well as the fact that more than half of all vehicle trips in the U.K. are under 5 miles, are dire for limiting emissions of nitrogen oxides (NOx). As the company wrote:

The average daily distance driven in [U.K.] passenger cars is not sufficient for a vehicle’s pollution control system to warm up and become fully functional.

The resultant high levels of cold start NOx emissions, from both gasoline and diesel engines, could provide an additional challenge for urban air quality initiatives such as the proposed Clean Air Zones in the UK.

Read more: Green Car Reports

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