Table 2.

Average expired Carbon Monoxide according to smoking status.

Current smoking habit	Average of Carbon Monoxide expired before and after the interview
	Acceptable	At risk	Mean values
	(<6 ppm)	(≥6 ppm)
Never-smoker (45.2%)	107 (98.2%)	2 (1.8%)	2.26 ± 1.65
Ex-smokers (33.2%)	73 (91.2%)	7 (8.75%)	2.98 ± 2.69
Smokers (21.6%)	11 (21.2%)	41 (78.8%)	9.97 ± 6.50a
Total	191 (79.3%)	50 (20.7%)

Values presented as number (percentage) and mean ± standard deviation.

^ap = 0.02 vs. other groups.