Distribution of CO in 30 Homes with Unvented Gas Fireplaces

As part of a field measurement project of unvented gas fireplaces in 30 homes, portable carbon monoxide sensors were located in several places in each home. This was done to assess the degree to which combustion by-products became distributed throughout the home. The sensors indicated that carbon monoxide levels began rising throughout the home almost immediately, at or near the one-minute sampling interval. The results show that, on average, the reading in the middle of the fireplace room was about 95% of the reading at the mantel. Readings throughout the rest of the home are comparable to each other and are between 75-80% of the reading at the mantel at peak concentrations. These results indicate that carbon monoxide concentrations from unvented fireplace combustion spread rapidly and rather uniformly throughout the house.