Grass pollen allergy in children and adolescents-symptoms, health related quality of life and the value of pollen prognosis

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–