Clean or replace the air filters regularly to prevent this issue
During 2011 and 2015, significant increases were observed among middle and high school students for current use of e-cigarettes and hookahs, while decreases were observed for current use of conventional tobacco products, such as cigarettes and cigars, resulting in no change in overall tobacco use
However, others argue that because the moisture in the leaf is often bound with sugars and casings, it doesn't freeze in the same way that pure water does
Am J Respir Cell Mol Biol 6:287295 Di Stefano A, Maestrelli P, Roggeri A, Turato G, Calabro S, Potena A, Mapp CE, Ciaccia A, Covacev L, Fabbri LM, Saetta M (1994) Upregulation of adhesion molecules in the bronchial mucosa of subjects with chronic obstructive bronchitis