Carboxyhaemoglobin levels in some Lagos dwellers--a pilot study

Carboxyhaemoglobin (COHb) concentrations were determined by differential spectrophotometry in blood of 60 healthy adult subjects from various locations in Lagos. Half of these were either occasional or regular tobacco cigarette smokers. Our findings showed that the Lagos dweller has elevated COHb concentration ranging between 7.6%-9.9%, several folds higher than permitted by Air Quality Standards. The range and scatter of COHb in smokers were wider (7.4%-13.0%) than in non smokers. In particular, COHb concentrations were significantly higher in regular smokers than in non smokers by Fisher's exact test (p < 0.0006). Elevated COHb concentrations among smokers were related to frequency of tobacco use (p < 0.01). There was however no statistically significant difference in COHb concentrations when the regular and occasional smokers were taken as a group and compared with the non smokers. Haematocrit measurements showed that a degree of anaemia was present in most of the subjects tested irrespective of smoking status (mean packed cell volume = 36.1). It is inferred from this data that the Lagos dweller has high ambient concentrations of COHb and that these may be further aggravated by cigarette smoking.