On Friday 26 June, air quality may reach the “poor” level along the coast of Zeeland, Zuid-Holland and Noord-Holland. On Saturday 27 June, there is a chance of smog due to ozone in a band across the central part of the Netherlands and in Noord-Holland. This could cause discomfort for people who are sensitive to smog. RIVM advises them to stay indoors and limit strenuous physical activity. This advice is most relevant in the late afternoon and early evening, when the air will be most polluted.

Smog from ozone may cause a worsening of respiratory symptoms, such as coughing and shortness of breath, as well as a worsening of asthma symptoms and reduced lung function. It may also irritate the eyes, nose and throat. Relatively speaking, people with respiratory symptoms, children and the elderly are most sensitive to smog. Contact your GP if you experience symptoms.

Ozone forecast for the days ahead

The situation for Sunday 28 June is still uncertain. During the course of Sunday, cooler air will move into the Netherlands from the west. This will lead to increased cloud cover, conditions under which less ozone is formed. 

For today, Thursday 25 June, smog due to ozone is only expected in Zeeland, Noord-Brabant and Limburg. In the central part of the country, ozone concentrations are now expected to be lower than previously forecast.

Smog due to ozone

Smog due to ozone is the result of an accumulation of pollutants in the air on sunny days. This occurs in spring and summer when there is little wind (that is mainly blowing from the south-east). The pollutants include nitrogen oxides and volatile organic compounds, which the sunlight turns into ozone. This is also known as ‘summer smog’. In other seasons, the UV radiation is not high enough to create significant amounts of ozone concentrations.

(European Union) information and alert thresholds for ozone

The EU has established information and alert thresholds for ozone. The EU information threshold is 180 micrograms per cubic metre of air. When this threshold is crossed (or about to be crossed), people who are sensitive to smog may start experiencing symptoms. RIVM will send out a warning when this happens. As per the Dutch air quality index, the air quality will be ‘poor’.

The EU alert threshold is 240 micrograms per cubic metre of air (air quality ‘very poor’ according to the Dutch air quality index). When this threshold is crossed, everyone may start experiencing symptoms. RIVM will change the warning to an alert before this happens.

More information