Air pollution levels along stretches of motorway where the speed limit has been increased to 130kph remain below the maximum permitted under EU rules but the air quality has worsened in a few places, the public health institute RIVM said on Wednesday.

In 84% of cases, the level of nitrogen dioxide in the atmosphere has actually dropped when compared with 2015. Pollution had increased at 5.5% of the test sites but remained within EU limits.

Over 71,000 measurements were taken near roads where the speed limit has been raised to 130 kph this year.

Although cars emit more pollutants at higher speeds, ‘in practice, the improvements in air quality in the past few years have offset the extra contributions [to air pollution] made by traffic,’ the RIVM said.

The EU limit for fine particulates is being broken in 13 of the 390 Dutch local authority areas – these are mainly in areas with high concentrations of factory farming or industry, the RIVM said.