Those glowing amber charcoals used on hookahs? They release high levels of dangerous toxic agents like carbon monoxide, metals and cancer-causing chemicals.
Cobb, Caroline, et al."Waterpipe Tobacco Smoking: An Emerging Health Crisis in the United States." American Journal of Health Behavior. 34(3). May-June 2010: 275–285. Web.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3215592/