Levoglucosan, an anhydrous sugar formed as a cellulose degradation product, has been used for nearly two decades as an atmospheric aerosol marker of wood burning. At the meeting, Hafiz Abdul Azeem and coworkers at Lund University reported that it could also be a marker for smoldering fires in stored dry biomass for use in energy production. A low-temperature fire inside a stack of biomass can smolder for days, weeks, or even longer without producing flames and thus escape detection. To determine whether levoglucosan can be detected from smoldering fires, the researchers packed cotton into a concrete block and triggered smoldering with heating wires. They collected aerosol particles on quartz filters at approximately 30-minute intervals. They extracted and analyzed the particles by gas chromatography-mass spectrometry. They kept data from only those experiments in which the cotton started blackening within three hours and in which the stack went into flames after eight hours. “From approximately three hours onward, we can see some blackening in the cotton stack,” Azeem told C&EN. “In some of our batches, we were able to see levoglucosan on the filter collected after the first 30 minutes,” meaning they could detect levoglucosan before any visible signs of smoldering.