Pollen and allergies in Saint-Louis
The highest pollen in Saint-Louis today is ragweed, at 27 grains/m³ — a high level.
Modelled for Friday 4 September, 02:00
Pollen in Saint-Louis today
| Pollen | Count | Level |
|---|---|---|
| AlderAlnus | 0grains/m³ | None |
| BirchBetula | 0grains/m³ | None |
| OliveOlea | 0grains/m³ | None |
| GrassPoaceae | 2.0grains/m³ | Low |
| MugwortArtemisia | 1.1grains/m³ | Low |
| RagweedAmbrosia | 27grains/m³ | High |
The next 4 days
Daily maximum counts in grains/m³. Only grass, mugwort and ragweed pollen rise above zero in this window; the rest are out of season.
| Day | Grass | Mugwort | Ragweed | Level |
|---|---|---|---|---|
| Today4 Sept | 2.0 | 1.1 | 27 | High |
| Tomorrow5 Sept | 1.7 | 1.1 | 12 | Moderate |
| Sunday6 Sept | 2.0 | 2.0 | 21 | High |
| Monday7 Sept | 1.9 | 1.9 | 0.1 | Low |
This season so far
The highest daily count recorded for each pollen in Saint-Louis since 4 June, which puts today's figures in context.
| Pollen | Peak count | Reached on | Level |
|---|---|---|---|
| Birch | 1.4grains/m³ | Monday 8 June | Low |
| Olive | 1.0grains/m³ | Monday 8 June | Low |
| Grass | 156grains/m³ | Wednesday 10 June | High |
| Mugwort | 23grains/m³ | Thursday 30 July | Moderate |
| Ragweed | 29grains/m³ | Thursday 3 September | High |
What this means for you
Most people allergic to this pollen will have symptoms. Limit long spells outdoors in the late morning and early evening, wear wraparound sunglasses, and shower and change clothes when you get home.
How pollen levels are scored
Thresholds differ by plant, because the amount of pollen it takes to provoke symptoms differs by plant. A count of 20 is a moderate grass day and a very high ragweed one.
| Pollen | Low | Moderate | High | Very high | Usually in the air |
|---|---|---|---|---|---|
| Alder | 1–9 | 10–99 | 100–999 | 1000+ | January to March |
| Birch | 1–9 | 10–99 | 100–999 | 1000+ | March to May |
| Olive | 1–49 | 50–199 | 200–999 | 1000+ | April to June |
| Grass | 1–19 | 20–49 | 50–199 | 200+ | May to August |
| Mugwort | 1–9 | 10–29 | 30–99 | 100+ | July to September |
| Ragweed | 1–9 | 10–19 | 20–49 | 50+ | August to October |
How these figures are produced
These counts come from the Copernicus atmospheric monitoring service, which models pollen concentrations on a grid across Europe, sampled at the coordinates of Saint-Louis. They are modelled values rather than grains counted at a pollen trap in the town, so neighbouring localities in the same grid cell will show similar figures, and a tree in flower on your street can matter more than the number here. Treat them as a regional indication. They are not medical advice: if symptoms are severe or persistent, speak to a doctor or pharmacist.
