Table 1.

The category of pollen counts

Category	Pollen grains per cubic meter of air
	Tree	Grass	Ragweed
No sample	–	–	–
Absent	0	0	0
Low	0–15	0–5	0–10
Moderate	15–90	5–20	10–50
High	90–1500	20–200	50–500
Very high	>1500	>200	>500