Instead of acetate or cardboard filters, it consists of two ceramic caps on either sides containing activated charcoal, which reduces tar and other toxins in the smoke
Once harvested, the briar must be boiled and dried to remove sap and moisture, but the process is long and must be carefully controlled to prevent the briar blocks from drying too quickly, which can result in splits or fissures in the wood
Source: NIDA How will I know if Im too high
This report is also available for download at: Cancer Research UK This report should be referred to as follows: Stead, M., Hitchman, S.C., Angus, K., Aleyan, S., Ford, A., MacKintosh, A.M., Purves, R., Mitchell, D., Hammond, D., Fong, G.T., Driezen, P., Reid, J., Craig, L., Chung-Hall J., Cummings, K.M., Thrasher, J.F., Cho Y.J., Cowell, C., Coker, T., Bullock, S., Froguel, A., Vohra, J., E-cigarette marketing in the UK: evidence from adult and youth surveys and policy compliance studies. Cancer Research UK