Carbon monoxide in firemen before and after exposure to smoke

A statistically significant difference was found between the mean baseline carboxyhemoglobin of non-smoking firemen (COHb 2.53, sd = 1.05, n = 32) and smoking firemen (COHb 5.54, sd = 2.61, n = 26). A consistent increase in mean COHb levels after exposure to smoke was seen in both non-smoking (4.41 sd = 2.95, n = 7) and smoking men (8.74, sd = 5.66, n = 11), but the mean increase in these two groups was statistically significant only at the 90 percent level (t = 1.85, df = 16, p less than 0.1).