According to the World Health Organisation (WHO), particulate matter affects more people than any other pollutant. Generally two types of particulate matter are distinguished; those with a diameter less than 10 μm (PM10) and those with a diameter less than 2.5 μm (PM2.5). For comparison: fine beach sand has a typical diameter of 90 μm. Exposure to these particles is detrimental for your health and increases the risk of developing lung cancer.
The Dutch Rijksinstituut voor Volksgezondheid en Milieu (RIVM) has multiple stations across the Netherlands, which measure the concentrations of PM10 and PM2.5. A distinction can be made between stations in cities, stations along busy roads and regional background stations. The graph shows per station type the monthly averaged particulate matter concentration in the Netherlands. The shaded region around each line shows the standard deviation and is measure for the variation from station to station. On the map the stations can be seen which data has been used. You can use the buttons to switch between PM10 and PM2.5 data. For PM10 there is no data available for 2012 due to calibration issues.
The EU has set limits for PM10 and PM2.5, which are shown as a purple dashed line. In addition, the WHO provides guideline values (the orange dashed line). It can be seen that the air quality in the Netherlands is generally quite good, but a strong seasonal variation is visible.