Privacy & cookies
What we store, what we measure, and how to remove all of it.
Cookies
We do not use them. This site sets no cookie at all, not even a functional one. If you see an indication elsewhere that it does, it did not come from us.
What is stored on your device
We use localStorage: storage inside your own browser that, unlike cookies, is never sent to a server automatically. Everything below stays on your device until you delete it.
| What | Purpose | When |
|---|---|---|
theme | Remembers whether you chose the light or dark view | When you use the switch |
pa_locationpa_provincie | Remembers your town or province so you need not enter it every time | When you pick a location |
pa_dagboek_token | A random number that ties your diary entries together. No name, no email address, nothing that leads back to you | Only the moment you save your first answer |
pa_popup_af | Remembers that you dismissed an invitation, so it does not return | When you dismiss something |
If you only drop by to look at the pollen levels, nothing is placed on your device at all. That is deliberate.
The hay fever diary
When you record how you feel, we keep that answer together with the measured pollen concentration of that day. That is what lets us show you, after a week or two, which pollen type your symptoms line up with.
No name, email address or IP address is attached to it, only the random number from the table above. We cannot see who you are — and by the same token you cannot find your entries again on another device.
Delete pa_dagboek_token and the link to your entries is gone for good. The
individual rows stay in the anonymous statistics; at that point nobody can tie them to a
person, ourselves included.
Email alerts
If you sign up to be told when pollen levels rise, we keep your email address, your province and the level from which you want to hear from us. That sits in a separate table with no reference to your diary — the two are deliberately impossible to connect.
You first receive an email to confirm your sign-up; without that confirmation we never send you anything. Every message carries an unsubscribe link, and unsubscribing deletes your data immediately, not later.
Push notifications
If you switch notifications on, we store the subscription your browser creates for it. It holds no personal data and works only in the browser where you enabled it. You turn it off in your browser settings or with the button on the site.
Visitor statistics
We measure how many people visit and which pages they read, using Umami on our own server in Europe. This happens without cookies and without placing anything on your device. No profile is built, you are not followed across other sites, and the data does not go to advertising companies.
What we load from third parties
- Map imagery for the pollen maps, and the mapping library that draws them.
- Pollen data comes from the European Copernicus programme (CAMS) and from the pollen counts of Elkerliek Hospital. We fetch those; your browser does not talk to them.
Fonts and icons have been served from our own server since 14 August 2026. They used to come from Google Fonts and cdnjs, which saw every visitor's IP address in the process. That is no longer the case.
Erasing everything
In your browser settings, under site data or storage for pollenalert.nl, you wipe everything above in one go. For email alerts, use the unsubscribe link from any of the messages.
Your rights
You have the right to access, correct and delete your data. For the diary that is directly in your own hands: it is anonymous and you erase it yourself. For email alerts you can write to us, or simply use the unsubscribe link — that removes everything we hold about you.
If you have a question or a complaint, get in touch via the contact details on our FAQ page. You may also lodge a complaint with the Dutch Data Protection Authority.
Last updated: 14 August 2026. If anything material changes about what we store, we update this page before that change goes live.