In preparing a waterpipe for use, perforated aluminum foil is placed across the shisha head. The aluminum foil is used to prevent the charcoal from touching, and thereby burning the shisha, which would result in the formation of chemicals associated with smoking-related disease. However, this arrangement does permit the chemicals released from the burning charcoal, such as carbon monoxide, to be drawn through the perforations into the shisha cloud.
The use of an HMD reduces exposure to chemicals generated from the burning charcoal by preventing them being drawn through the waterpipe into the shisha cloud.
A Heat Management Device (HMD) is an alternative to perforated aluminum foil, and broadly consists of a metal box in which the charcoal is contained incorporating a ventilation mechanism to modify the burn rate of the charcoal.
HMDs are generally made from aluminum, which ensures the shisha head is more evenly heated. This results in a denser shisha cloud, while also significantly reducing the passage of chemicals from the burning charcoal.
In a study conducted by AIR in 2019, the “Kaloud Lotus” HMD device significantly increased shisha cloud density, likely because of more uniform heating, while reducing carbon monoxide yields compared to the use of a conventional shisha head covered with perforated aluminum foil.