Air pollution in major cities gets worse as the temperature rises beyond 30C says a new study which has focused on Paris over the summer months.

Research by The Real Urban Emissions (True) initiative focused on diesel car emissions and found that nitrogen oxides were 20% to 30% higher when temperatures rose above 30C.

One of the most worrying aspects of the French study was that emissions from a number of car manufacturers was way above the figures declared by the brands in their own literature. With the Volkswagen Dieselgate scandal still fresh in the mind for many, the news that cars are pumping out way more toxins than originally thought will be hard to take for many environmental campaigners.

The True research looked at the emissions of more than 180,000 vehicles in Paris over three weeks in the summer of 2018, with the aim of finding the real emissions of vehicles in a range of driving and traffic conditions. True conducted similar research in London in 2017.

Speaking to The Guardian Karine Léger, managing director of Airparif, which monitors Paris air quality, said: “The quality of the air we breathe depends on emissions, that is to say, the amount of pollutants released into the atmosphere. But there is no simple connection between the two, given the influence of meteorology and atmospheric chemistry.

“As a result, the one-shot measurement campaign carried out by the True project on a 180,000-vehicle sample in Paris provides important insights. It allows us to go further in interpreting the trends in air quality breathed in Paris with regard to emissions related to road traffic, which remains the main source of pollution in the capital.”

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