Chronic CO Exposure Stats:
The mean duration of CO exposure was 28.4 months (+/-4.4 mo.), or nearly 2.5 years, with a range of 0.75 - 120 months. No respondent reported being unconscious due to CO at any time during exposure. The mean period of time after termination of CO exposure that responses were given was 21.4 months (+/-2.2 mo.), or nearly 2 years, with a range of 0.25 - 60 months.
The source of CO in most cases was a furnace (boiler, heater, etc.) (48, 58.5%), while the source in a substantial number of cases was a water heater (19, 23%) or a range (cooking stove) (12, 14.6%). Faulty chimneys and flues (3), and internal combustion engines (4) were the CO source in a few cases. In several cases more than a single source was identified, eg. furnace and water heater.
Air CO concentration had a mean value of 220.4 ppm (+/-28.1 ppm) for 25 cases. Thus, only a fraction the respondents knew the measured CO value in their case. The mean COHb saturation reported was 9.0 % (=/-1.6%) for 29 cases. Again, only a fraction the respondents knew their measured blood CO value. COHb corrected for the time delay between leaving the CO uptake site and the blood draw (when possible) gave a value of 14.0% (+/-2.4%) in 22 cases.
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