Table 1. Airborne asbestos fiber concentrations by region.

Regions	No	SEM (f/ ml)					PCM (f/ ml)
		GM	GSD	Min	Max		GM	GSD	Min	Max
South	11	0.14 1	0.062	0.02	0.25		0.05	0.022	0.01	0.09
East	12	0.13 2	0.145	0.05	0.42		0.04	0.051	0.02	0.15
West	11	0. 31	0.082	0.17	0.43		0.11	0.029	0.06	0.15
Centre	11	0.20 3	0.065	0.08	0.34		0.07	0.023	0.03	0.12
Total	45	0. 20	0.111	0.02	0.36		0.07	0.039	0.01	0.15

¹p< 0.001, ²p<0.01, ³p=0.07, compared with the western area of Tehran. GM, geometric mean; GSD, geometric standard deviation; max, maximum; min, minimum; SD, standard deviation; SEM, scanning electronic microscopy; PCM, phase contrast microscopy.