Figure 3.

A, Mean carbon monoxide (parts per million) measured at baseline (visit 1) and the following four follow-up visits (visits 2 to 5) for each individual. The plotted shape represents a density estimate. The Y-axis truncated at a value of 10 (maximum observed mean carbon monoxide = 303 parts per million). B, Mean carboxyhemoglobin per individual measured at at baseline and the following four follow-up visits for each individual. The plotted shape represents a density estimate. The Y-axis truncated at a value of 25 (maximum observed carboxyhemoglobin = 26). ppm = parts per million. See Figure 2 legend for the expansion of the other abbreviations.