Carbon monoxide as a tracer for assessing exposures to particulate matter in wood and gas cookstove households of highland Guatemala

Kitchen-area 22-h gravimetric PM2.5 and passive diffusion stain-tube carbon monoxide (CO) concentrations were measured in homes with open fire and imp roved wood cookstoves in two studies. In the first study (Guat-2), which al so studied homes with gas cookstoves, three samples were collected per stov e condition from each of three test houses. In the second study (Guat-3), o ne sample was collected per house from 15 open fire and 25 improved-stove h ouses. CO personal samples were also taken for mother and child in both stu dies. Spearman correlation coefficients (R) between kitchen-area CO and PM2 .5 levels in homes using open fires or impoved wood cookstoves were high ra nging from 0.92 (Guat-2) to 0.94 (Guat-3), as were those between the person al samples for mother and child ranging from 0.85 (Guat-3) to 0.96 (Guat-2) . In general, the correlations were lower for less-polluted conditions. The study found that CO is a good proxy for PM2.5 in homes using open fires or planchas (improved wood cookstove with chimney) but not under gas stove us e conditions. It also determined that mother personal CO is a good proxy fo r child's (under 2 years of age) personal CO and that area CO measurements are not strongly representative of personal CO measurements. These results generally support the use of Draeger CO passive diffusion tubes as a proxy for PM2.5 in such cases where a single type of emission source is the predo minant source for CO and PM2.5.