Pollen DK - Home Assistant Integration

Home Assistant custom integration that fetches live pollen data for Denmark from Astma-Allergi Danmarks official JSON feed.

Data source: https://www.astma-allergi.dk/umbraco/Api/PollenApi/GetPollenFeed This is the same backend used by Astma-Allergi Danmarks own app and website — not a scraper.

Disclaimer: This integration is an independent community project and is not affiliated with, endorsed by, or in any way connected to Astma-Allergi Danmark.

Requires Home Assistant 2026.6.0 or newer.

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Features

• No scraping — uses the official JSON API endpoint
• Two measurement stations: København (Østdanmark) and Viborg (Vestdanmark)
• 8 pollen/spore types: Birk, Bynke, El, Elm, Græs, Hassel, Alternaria, Cladosporium
• Raw count sensors (pollen/m³) with severity attribute for each type
• Overall severity sensor per region (worst level across all types)
• 5-day forecast — per-allergen daily counts and worst-severity summary per day
• Custom Lovelace card — visual forecast grid with severity dots and detail popup
• UI config flow — no YAML required
• Updates every hour (data itself refreshes once daily ~16:00 CET)

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Sensors created

For each configured region you get:

Entity	Description
sensor.pollen_dk_birk_REGION	Birch pollen count (pollen/m³)
sensor.pollen_dk_bynke_REGION	Mugwort pollen count
sensor.pollen_dk_el_REGION	Alder pollen count
sensor.pollen_dk_elm_REGION	Elm pollen count
sensor.pollen_dk_graes_REGION	Grass pollen count
sensor.pollen_dk_hassel_REGION	Hazel pollen count
sensor.pollen_dk_alternaria_REGION	Alternaria mold spore count
sensor.pollen_dk_cladosporium_REGION	Cladosporium mold spore count
sensor.pollen_dk_pollenvarsel_REGION	Overall worst severity level

Each count sensor includes the following attributes:

• severity — none / low / moderate / high / very_high / unknown
• pollen_type_da — Danish name
• pollen_type_en — English name
• last_update — Date of last measurement
• region — Station name
• forecast — dict of upcoming dates → predicted pollen count (e.g. {"28-04-2026": 2, "29-04-2026": 5, ...}). Out-of-season types have an empty dict.

The overall severity sensor includes:

• pollen_levels — dict of all in-season types with count + severity
• forecast — dict of upcoming dates → worst severity across all allergens (e.g. {"28-04-2026": "low", "29-04-2026": "moderate", ...})
• last_update

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Lovelace card

The integration ships a custom Lovelace card, custom:pollen-dk-card, that is automatically registered when the integration loads — no manual resource configuration needed.

Card	Detail popup

Adding the card

In the Lovelace dashboard editor, click Add card, scroll to Pollen DK, and pick a region. The card is fully configurable from the visual editor — no YAML required.

Minimal YAML:

type: custom:pollen-dk-card
region: koebenhavn

Card options

Option	Default	Description
title	(translated)	Card heading. Leave empty to use the language-aware default.
region	—	koebenhavn or viborg (required)
days	5	Number of days to show, including today (1–5)
pollen_types	(all)	Limit which pollen types are shown. Empty list = show all.

Card behaviour

• Only in-season types are shown — types with severity none or unknown are hidden automatically.
• Responsive columns — the number of day columns adjusts to the card width so dots never overflow.
• Language-aware — day labels, severity labels, pollen names and the card title follow the HA language setting. Danish and English are fully supported.
• Severity dots use a colour scale: ● Low · ● Moderate · ● High · ● Very high
• Click any row to open a detail popup with a severity gauge, threshold reference, and measurement date.

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Adding a language to the card

The card currently supports Danish (da) and English (en). Any other HA language falls back to English automatically. Adding a new language requires a single edit to custom_components/pollen_dk/www/pollen-dk-card.js.

Step 1 — add a translation entry

Inside the TRANSLATIONS constant, add a new key for the BCP 47 language tag that Home Assistant uses (e.g. "de" for German, "nl" for Dutch). Copy the en block and translate every string value. Functions that receive arguments must keep the same signature.

const TRANSLATIONS = {
  da: { /* … */ },
  en: { /* … */ },

  de: {                                          // ← new language key
    default_title: "Pollenvorhersage",
    today: "Heute",
    weekdays: ["So", "Mo", "Di", "Mi", "Do", "Fr", "Sa"],
    severity: {
      none: "Keiner",
      low: "Niedrig",
      moderate: "Mäßig",
      high: "Hoch",
      very_high: "Sehr hoch",
      unknown: "Unbekannt",
    },
    no_data: (region) =>
      `Keine Pollendaten für ${region} gefunden.<br>Prüfen Sie die Integration.`,
    popup: {
      low: "Niedrig",
      moderate: "Mäßig",
      high: "Hoch",
      under: "Unter",
      between: "Zwischen",
      over: "Über",
      pollen: "Pollen",
      measured: (date, region) => `Gemessen am ${date} — ${region}`,
    },
    descriptions: {
      birk: "Birkenpollen erreichen typischerweise Ende April ihren Höhepunkt.",
      bynke: "Beifußpollen ist von Juli bis September in der Luft.",
      el:   "Erlenpollen verbreitet sich früh im Frühling, typischerweise März–April.",
      elm:  "Ulmenpollen verbreitet sich im Frühling, typischerweise April–Mai.",
      graes: "Gräserpollen ist von Mai bis August in der Saison.",
      hassel: "Haselnusspollen verbreitet sich früh, typischerweise Januar bis März.",
      alternaria: "Alternaria ist ein Schimmelpilz mit Sporen in der Luft von Juli bis Oktober.",
      cladosporium: "Cladosporium ist der am weitesten verbreitete Schimmelpilz und von April bis November in der Luft.",
    },
    editor: {
      title: "Titel",
      region: "Region",
      days: "Anzahl Tage (inkl. heute)",
      pollen_types: "Pollentypen (leer = alle)",
      regions: {
        koebenhavn: "Kopenhagen (Ostdänemark)",
        viborg: "Viborg (Westdänemark)",
      },
      pollen_names: {
        birk: "Birke",
        bynke: "Beifuß",
        el: "Erle",
        elm: "Ulme",
        graes: "Gräser",
        hassel: "Haselnuss",
        alternaria: "Alternaria",
        cladosporium: "Cladosporium",
      },
    },
  },
};

Step 2 — copy the updated card file

After saving the file, copy it to config/www/ (development) or restart Home Assistant (production) so the browser picks up the new version:

cp custom_components/pollen_dk/www/pollen-dk-card.js config/www/pollen-dk-card.js

Keys reference

Key	Type	Used for
default_title	string	Card heading when the user leaves the title field empty
today	string	First column header in the forecast grid
weekdays	string[7]	Day abbreviations, Sunday-first (["Sun", "Mon", …])
severity.*	string	Dot tooltips and popup severity label
no_data	(region) => string	Message shown when no sensors are found
popup.low/moderate/high	string	Threshold row labels in the detail popup
popup.under/between/over	string	Threshold range words
popup.pollen	string	Unit word after the count ("pollen")
popup.measured	(date, region) => string	Footer line in the detail popup
descriptions.*	string	Seasonal description per pollen type in the detail popup
editor.title/region/days/pollen_types	string	Field labels in the visual editor
editor.regions.*	string	Region option labels in the visual editor
editor.pollen_names.*	string	Pollen type option labels in the visual editor

Submitting a translation

Contributions are welcome! Open a pull request with your new language block and it will be included in the next release.

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Installation

Minimum requirement: Home Assistant 2026.6.0

Via HACS (recommended)

1. In HACS → Integrations → ⋮ menu → Custom repositories
2. Add https://github.com/briis/pollen_dk as type Integration
3. Install Pollen DK
4. Restart Home Assistant

Manual

1. Copy the custom_components/pollen_dk folder to your HA custom_components/ directory
2. Restart Home Assistant

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Setup

1. Settings → Devices & Services → Add Integration
2. Search for Pollen DK
3. Choose region: København, Viborg, or Begge (creates sensors for both)
4. Done — sensors appear immediately

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Notes

• Outside pollen season sensors show 0 instead of unknown, and their forecast attribute is an empty dict.
• Data is published once daily around 16:00 CET. The integration polls hourly so you'll see the new values within an hour of publication.
• Astma-Allergi Danmark is a non-profit organisation. Please consider supporting them at astma-allergi.dk.

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Attribution

All pollen data is © Astma-Allergi Danmark. This integration is for personal, non-commercial use only, in accordance with Astma-Allergi Danmarks terms.