Table 3. Decompression sickness (DCS) number, incidence and relative risk ratio for PRE HBG by exposure group (see text for explanation) .

Q = P√t	DCS/no DCS	DCS (%)	DCS/no DCS	DCS (%)	RR	p-value
	PRE HBG = 1		PRE HBG = 0
[0−150]	0/4	0	0/353	0	NA	-
[150−200]	2/16	12.5	2/181	1.1	11.4	0.04
[200−250]	3/54	5.6	7/226	3.1	1.8	0.40
[250−300]	5/57	8.8	3/103	2.9	3.0	0.14