Table 5 Carbon monoxide in parts per million (ppm) in the exhaled air at 12-month follow-up, n = 99
CO concentration*Self-reported smokersSelf-reported non-smokers†n (%)
⩾7 ppm65 (80.2%)2 (11.1%)67 (67.7%)
0–6.5 ppm16 (19.8%)16 (88.9%)32 (32.3%)
n (%)81 (100%)18 (100%)99 (100%)

  • *Measured with a NeoMed EC50 CO analyser (see Methods); †7-day abstinence.