New, stricter norms for nitrogen-based emissions need to be set every 10 years, according to a Wageningen University report conducted for the government.

NOS reports that the emission limit known as the critical deposition value (KDW) and based on how much pollution natural areas can withstand without worsening, will need to be tightened.

On average, nitrogen compound emissions will have to shrink by 7% in nature reserves, but the worst-polluted areas will need a 36% reduction. EU nature law means that governments are obliged to ensure the state of protected areas of nature does not worsen.

According to an NOS analysis, in almost half of sensitive nature reserves, the norms will have to be tightened, in 3% they can be relaxed and nothing will change for the rest.

The caretaker government aims to reduce pollution to within limits in three quarters of these areas by 2030, although the Christian Democrats said the year was “not holy”. But if norms are tightened up, the goals will be harder to reach.

Environment minister Christianne van der Wal told the NOS that the new figures were “worrying for nature and for everyone who is working so hard on our shared task to restore nature” because “the new scientific insights have increased our task.”

Political parties such as the BBB Farmer Citizen Movement have criticised the KDW saying that it is a theoretical limit rather than being based on actual measurements in nature.

However the Wageningen researchers told NOS that it is “on the conservative side” and that any other method with have even more radical consequences.