title: Comparison of end tidal carbon monoxide (eCO) levels in shisha (water pipe) and cigarette smokers.
abstract: BACKGROUND
  Measuring eCo is rapid, non-invasive and inexpensive tool and correlate correctly with carboxyhemoglobin levels in blood. The aim of this study was to evaluate and compare the increase in end tidal carbon monoxide (eCO) levels in exhaled breath of passive smokers and healthy smokers after cigarette and shisha smoking.
  
  
  RESULTS
  In a cross sectional study eCO levels were measured in 70 subjects (24 cigarette smokers, 20 shisha smoker, 26 passive smokers) by use of portable device. Smokers were asked to smoke shisha for 30 mins in shisha cafe or to smoke 5 cigarettes in 30 mins in a restaurant. eCo levels were measured at baseline (30 mins), 35 mins, 60 mins and 90 mins in all groups after entry to the venue. The baseline mean eCO level among cigarette smokers was 3.5 +/- 0.6 ppm (part per million), passive cigarette smokers 3.7+/-1.0 ppm, shisha smokers 27.7+/-4.9 ppm and passive shisha smokers 18.3+/-8.4 ppm .The mean increase in eCO after 90 min among smokers was 9.4+/-4.6 (p < 0.005), passive cigarette smokers 3.5+/-2.5 (p < 0.05), shisha smokers 57.9+/-27.4 (p <0.005) and passive shisha smokers 13.3+/-4.6 (p = 0.03).
  
  
  CONCLUSIONS
  Exposure to shisha smoke is a cause of elevated eCO in smokers and passive smokers and due to in-door pollution, sitting in shisha bar causes significant increase in eCO levels.
authors.affiliation: Post-graduate trainee in pulmonology Department, Jinnah Post Graduate Medical Center, Karachi, Pakistan.
authors.forename: Saima
authors.initials: S
authors.lastname: Akhter
authors.affiliation: Chair Person business administration, Indus University, Karachi, Pakistan.
authors.forename: Usman
authors.initials: U
authors.lastname: Ali Warraich
authors.affiliation: Head of Department in pulmonology Department, Jinnah Post Graduate Medical Center, Karachi, Pakistan.
authors.forename: Nadeem
authors.initials: N
authors.lastname: Rizvi
authors.affiliation: Post-graduate trainee in pulmonology Department, Jinnah Post Graduate Medical Center, Karachi, Pakistan.
authors.forename: Nusrat
authors.initials: N
authors.lastname: Idrees
authors.affiliation: Post-graduate trainee in pulmonology Department, Jinnah Post Graduate Medical Center, Karachi, Pakistan.
authors.forename: Fatima
authors.initials: F
authors.lastname: Zaina
keywords: Cigarette smoker; End tidal carbon monoxide levels (eCO); Restaurants; Shisha; Shisha cafes; Shisha smokers