The National Institute for Public Health and the Environment (RIVM) has issued a warning for high levels of ozone in the Netherlands on Tuesday, 26 May 2026. The highest concentrations appear to be occurring in a band from Leiden towards Hilversum, Utrecht and Flevoland, reaching as far as Zwolle. Air quality in and near this band may be ‘poor’ due to smog from ozone.

An RIVM questionnaire survey shows that most Dutch people know that animals can transmit infectious diseases. However, people are unfamiliar with all the ways in which they can become infected. And they do not always know the measures which can protect them. For example, half of those surveyed do not wash their hands after contact with pets.