Health authorities are reportedly focusing on contaminants or counterfeit substances as a possible cause of vaping-related lung illnesses. The Washington Post reports that there are now up to 354 possible cases in 29 states, nearly double the number reported to be under investigation last week. Rather than scrutinizing standard vaping products that have long been available, investigators have started focusing on contaminants in light of the sudden onset of these recent illnesses combined with patients’ distinctive symptoms. The investigation is looking into which solvents are being used, especially in counterfeit and DIY products, including potentially mislabeled solvents. While investigators are getting closer to finding the cause, they caution that they’re still a long way from understanding what exactly is making so many people sick.