On Friday 14 August, air quality is expected to be “poor” in the central, eastern and northern parts of the Netherlands. 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 from early afternoon into the 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

In the early evening, the wind will change to a northerly direction and bring in cleaner, cooler air. This type of weather leads to less ozone being formed. As a result, ozone levels will drop quickly and smog will disappear. No smog is expected during the weekend or in the days after.

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