Poor ventilation, particularly in the kitchen, is pushing fine particulate pollution levels to above the yearly average considered safe by the World Health Organisation in some Dutch homes according to research institute TNO.

While the probe was too limited for the results to be applicable on a national level, it is a good indication of what is happening in many Dutch homes, TNO researcher Piet Jacobs told the Volkskrant. In total, 101 homes in the research project provided reliable measurements.

Fine particulate pollution causes respiratory problems and increases the risk of heart and lung disease. TNO, which used sensors to measure particulate levels, measured an average of ten day on which the levels where higher than the WHO norm, with some homes never exceeding the level and some showing excessive levels on more than 35 days.

In winter levels are higher, because windows tend to be closed, the researchers said. Cooking is one of the most important culprits, apart from smoking, which was not included in the probe. This was because, Jacob said, smoking ‘leaves all other sources of particulates standing’.

Peak levels of particulates were measured  when people were cooking, the probe found. Good extraction systems are needed but nothing has been included about their quality in building regulations, Jacob said.

Most new builds have a basic system which are incapable of providing enough ventilation, he said, while re-circulation extraction systems only filter the air and do not expel it. This type of system only removes about 30% of particulates during cooking, the investigation found.

The probe found that around half of the fine particulate pollution in the homes came from sources outside, such as traffic and industry and half came from inside.