Dear Sir,

The authors thank Lange and Cegolon for pointing out the error in Table I and for their thoughtful comments, which have helped to improve our article.

In Table I, the normal range for carboxyhaemoglobin (HbCO) has been corrected to 0%–10%, and a footnote regarding the HbCO range for non-smokers (0%–2%) and smokers (0%–10%) was also added.

Yours sincerely,