. 2010 Sep 21;2010:213960. doi: 10.1155/2010/213960

Table 4.

Carbon Monoxide Concentration Data (ppm).

Site	Highest 15-minute average		Highest 30 minute average		Highest 60 minute average
Site	Personal	Area	Personal	Area	Personal	Area
1	120^A	90^A	110^B	88^A	95^B	85^B
2	58	71	55^A	61^A	46^A	48^A
3	35	36	32	27	31^A	22
4	58	47	49	40	46^A	37^A
5	58	31	26	45	32^A	19
6	56	34	32	50^A	50^B	31^A
7	52	14	13	45	39^A	13
8	37	19	15	25	21	11
9	115^A	74	57^A	86	74^B	49^A
10	38	40	33	34	24	28^A

Median	57	38	32.5	45	42.5	29.5
GM	57	39	35	46	41	29
GSD	1.53	1.81	1.89	1.54	1.60	1.88

^A: Exceeds the WHO guideline

^B: Exceeds twice the WHO guideline

WHO guidelines—concentrations not to be exceeded for averaging times, 15 minute: 90 ppm, 30 minutes: 50 ppm, 60 minutes: 25 ppm [12].