Table 2.

Summary statistics for airborne benzene level according to sampling characteristics

Sampling characteristics	No. of measurements	AM(w), ppm	SD, ppm
Sampling duration
≤ 15 min	2,457	15.4	25.2
≥ 1 h	10,279	0.9	4.1
No information	2,993	49.5	27.9
Sampling type
Personal	12,819	3.5	12.6
Area∗	2,362	49.0	27.3
No information	548	0.2	0.5
Total	15,729	10.2	22.6

AM(w), weighted arithmetic mean; SD, standard deviation.

^∗Include measurements done with a colorimetric detector tube.