RT Journal Article SR Electronic T1 Carbon monoxide levels in water pipe smokers in rural Laos PDR JF Tobacco Control JO Tob Control FD BMJ Publishing Group Ltd SP 517 OP 518 DO 10.1136/tobaccocontrol-2012-050431 VO 21 IS 5 A1 Jaime Rivas Lopez A1 Khamphithoune Somsamouth A1 Boualoy Mounivong A1 Ryan Sinclair A1 Pramil N Singh YR 2012 UL http://tobaccocontrol.bmj.com/content/21/5/517.abstract AB