When Daniel Skousen scrubs at the ash and soot covering his Maui home, he worries about the smell. More specifically, he worries about what chemicals created the burning-trash-barrel scent that has lingered since a deadly wildfire tore through Lahaina in August. He wants an independent expert to check the environmental safety testing being done by government agencies, but so far he hasn't been able to get the raw data. Environmental Epidemiologist Irva Hertz-Picciotto studies the health effects of such fires. She says there's a lot that scientists don't yet know about the long-term health impacts of wildfires like the one that destroyed Lahaina.