Table 3 Odds Ratios for symptoms at different threshold levels between different pollen grain levels
| Threshold level (pollen grains per cubic metre) | |||
|---|---|---|---|
| Levels | Britain/Denmark | Sweden | Traffic lights |
| Low | 1–30 | 0–10 | 0–30 |
| Moderate | 31–50 | 11–30 | 31–80 |
| High | 51–150 | 31–100 | 81– |
| Very High | 150– | 101– | |