Table 2.

Expired CO and measures of withdrawal and craving in smokers

(n=38)	≤1-h abstinence prebreak	≤1-h abstinence postbreak	≥13-h abstinence prebreak	≥13-h abstinence postbreak
Expired CO (ppm)	23.5 (2.30)	24.5 (2.05)	6.60 (0.97)	12.0 (0.89)
UTS	4.38 (0.24)	1.93 (0.20)	5.78 (0.22)	2.58 (0.24)
SJSW
Craving	4.08 (0.17)	4.13 (0.21)	6.02 (0.17)	4.59 (0.17)
Psychological	2.70 (0.11)	2.95 (0.10)	3.76 (0.20)	3.05 (0.15)
Physical	1.59 (0.14)	1.52 (0.11)	2.17 (0.20)	1.78 (0.16)
Sedative	2.32 (0.22)	2.94 (0.24)	2.59 (0.21)	3.26 (0.29)
Appetite	3.89 (0.18)	4.32 (0.14)	4.18 (0.17)	4.15 (0.16)

Numbers indicate the means (standard errors of the means). CO levels decreased significantly more (from before to after the break) during the ≥13-h abstinence compared to ≤1-h abstinence.