<html><head></head><body data-blackberry-caret-color="#00a8df" style="background-color: rgb(255, 255, 255); line-height: initial;"><div style="width: 100%; font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br name="BB10" caretmarkerset="INVALID" class="markedForCaretMarkerRemoval"></div> <div style="width: 100%; font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br name="BB10" caretmarkerset="INVALID" class="markedForCaretMarkerRemoval"></div> <div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Good questions and good answers. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">My observations are that CO is vaguely/reasonably related to PM during the ignition and fuel pyrolysation stages. During the burn-out phase when char is smouldering the PM is low to zero and the CO can be very high, though not more than about 16% CO/CO2. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Left to its own devices a carbon fire runs 12-16 per cent. The highest CO seen was always during a high fire low excess air condition when it can reach 40 per cent or more. The PM2.5 can be very high in that condition. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Serum CO is a useful measure of exposure but it is not a good measure of the stove - only the stove-room ventilation as a combination or as a test of the ventilation. Dr KK Prasad (Eindhoven) did some modelling of stove emissions in standard rooms and found that the CO and smoke are not (at all) evenly distributed in a vented room. This is a further indication that a blood concentration s a poor measure of a stove. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">There is quite a mismatch between the metrics needed for human exposure and those needed for stove performance. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br name="BB10" caretmarkerset="INVALID" class="markedForCaretMarkerRemoval"></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">I recommend caution when reading material on these subjects, making sure the metrics are relevant to the claims being made. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Ambient air pollution is obviously related to the stove, but human exposure is directly related to the system, not just a major element of it. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">A study of the CO level in 'the home' found that the level 'in the kitchen' was pretty much the same as the rest of the house, but that is home-specific, and it does not mean the kitchen did not have high CO regions, or would not have. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Personal exposure is best measured with a purpose-built meter and there are lots of them available for industrial workers, both gases and PM, because the work environment is heavily regulated. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">JF did you see the article on ventilation I linked the other day? For warm countries it is a sensible option. </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Regards </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Crispin heading for the Stove Expo in Langfang </div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br></div><div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br name="BB10" caretmarkerset="INVALID" class="markedForCaretMarkerRemoval"></div><div id="_originalContent" style=""><div>
>Is CO content in the haemoglobin a good tracer for health impact?<br>
<br>
Interesting question: the major health impact from unvented stoves is<br>
perceived to be the long term effects of the smaller particulates, PM<br>
10 and PM2.5, these tend to be products of poor secondary combustion<br>
allowing carbon rings to form rather than burn out to CO2 and they<br>
combine to form Polycyclic Aromatic Hydrocarbons (things like benzo-a<br>
pyrene one of the pernicious carcinogens associated with tobacco<br>
smoking and lung cancer). <br>
<br>
These PACs in the particulates are particularly dangerous to the young<br>
and growing.<br>
<br>
So is there a direct relationship between PACs and CO concentration.<br>
<br>
Is there a long term effect from exposure to low levels of CO, we see<br>
people that stop smoking seem to have no long terms effects from CO<br>
exposure.<br>
<br>
AJH<br>
<br>
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