An unknown number of factory farms have been given permits on the basis of faulty calculations about how much they are likely to smell, according to officials in Noord Brabant province.

The officials have written to junior environment minister Wilma Mansveld urging her to come up with a speedy solution to the problem, which threatens to undermine the current licensing system, Trouw reports on Tuesday.

Some factory farms are much smellier than thought and should not have been granted a licence, while others were deemed likely to smell too much, which is not actually the case, the Brabant officials say. It is unclear how many farms are affected.

Complicated

The method used to calculate smell dates from 2007 but is too complicated for civil servants to use, Trouw reports. Instead, they use a simpler method which produces sharply different figures.

According to research group Witteveen+Bos the simplified method produces results which are 75% below actual smell concentrations or wildly overestimate the nuisance. Part of the problem is based on the way the impact of chimneys and ventilation are calculated.

The issue is particularly sensitive in Brabant because of protests about the development of mega factory farms, with tens of thousands of livestock, Trouw points out.

Officials have declined to say how many farms they think are affected.