The weather service MeteoSwiss is compiling annual graphic charts of the average daily pollen concentrations for the stations of the Swiss pollen measurement network. The 14 most important allergens are illustrated graphically for each station. The graphic charts are updated weekly during pollen season.
The black columns represent the average daily birch pollen concentration (pollen per m3) for the year 2016 in Bern. The average curve of daily pollen values, calculated for the 20-year reference period of 1996–2015 is shown with a blue background. The axis of the pollen concentration was limited in height, in order that also smaller values are visible, because they are important for allergy sufferers. Thereby the extreme concentrations are not given exactly. However, the precise value of the maximum is not really important for allergy, because the threshold for high birch pollen concentration starts already with 70 pollen/m3. The graphic chart in the example illustrates that the pollen loadfrequently was less severe than the long term average.
The start date, the number of days with high pollen concentration and the Seasonal pollen index can be illustrated with box plots. The example shows the number of days with high pollen concentration of the year 2016 in Bern compared with the 20-year series of measurement 1996-2015. The current year is depicted with a black diamond sign. The blue boxes represent the 25th and 75th quantileof the reference period and cover the central 50% of all values. The median (50%) is drawn as vertical line in the box. On the left and right side, lines are used to indicate the maximums and minimums of the distribution. The graphs of the current year show a preliminary result of the pollen season at the specific date.
The example shows 17 days of high hazel pollen load. This value is clearly higher than during a mean pollen season, which is shown in the blue box. The intensity of the hazel pollen season 2016 was as intense as in the most intense year of the reference period.