Answer: As is often the case, the answer depends on what you compare them to. Manufactured firelogs, such as those made by Duraflame and Java Logs, are made of compressed sawdust, vegetable and plant wax, and other recycled ingredients, such as ground nutshells or coffee grounds. These ingredients are mixed together and shaped into log like shapes.
For fireplace burning, these manufactured logs are a good, environmentally friendly alternative to conventional cut firewood for several reasons. First, their use of sawdust recycles waste and in the process saves trees. Second, their use of plant-based waxes uses carbon from a renewable source. It is also carbon-neutral, because its burning does not add extra carbon dioxide to the atmosphere and is thus more "climate" friendly. Finally, test reports have shown Duraflame and Java Logs to burn cleaner than cut cord wood, with substantially lower emissions of numerous air pollutants, such as particulate matter, carbon monoxide, formaldehyde, benzene, dioxin, and polycyclic aromatic hydrocarbons (PAHs). These air pollutant emissions are harmful to both environmental quality and public health. As a result of these notably lower emissions, many local environmental agencies and the US Environmental Protection Agency (EPA) recommend that people use manufactured logs in place of cut cord wood in their fireplaces. For example, the Puget Sound Clean Air Agency in Washington State has sponsored radio ads with Duraflame to promote the burning of manufactured logs in place of cut firewood in fireplaces. In addition, as compared to other home heating methods, the new logs are also more climate friendly when compared to natural gas fireplaces, since natural gas is a non-renewable fossil fuel.
However, from the air quality perspective, burning manufactured logs is still harmful to the environment, more so than burning natural gas. This is because wood burning, even in the form of manufactured firelogs, emits more local air pollution than most other heating methods. The negative impact of any wood burning is evident in many local air quality ordinances, many of which establish "no burn" days. For example, on bad-air days in the South Coast Air Quality District in Southern California (when the Air Quality Index is greater than 150), all wood burning — including that of manufactured firelogs — is forbidden. When the air quality is better but not good, as when the Air Quality Index is between 100 and 150, the agency still discourages all wood burning, but if wood burning is to occur, suggests that burning be limited to manufactured logs.
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Helen Suh MacIntosh is a professor in environmental health at Harvard University and studies how pollution behaves in the environment and how it affects people's health. Please keep in mind that her answers are just her interpretation of available information and should not be taken as the only viewpoint or solution to a problem. Use this column at your own risk. Having said this, please feel free to post any of your environmental health questions to Helen@TreeHugger.com. (Please use a descriptive email subject line and mention if you want to remain anonymous or not).