ASTM International Standard Specification for Maintaining Acceptable Water Activity ( a w ) Range (0.55 to 0.65) for Dry Cannabis Flower Intended for Human/Animal Use ASTM D8197-22

This specification prescribes the recommended range of water activity (aw) suitable for safe and efficacious storage of cannabis flowers or portions thereof. Water activity (aw) is defined as the partial vapor pressure of water in a substance divided by the partial vapor pressure of pure water at the same temperature, which can be calculated by dividing the partial vapor pressure of water in the substance by the partial vapor pressure of pure water at the same temperature. This describes quantitatively the capability of the cannabis flower in a sealed container to affect the humidity of the container's headspace air. aw shall be less than 0.65 to ensure against undesirable growth of microorganisms such as mold, and shall be greater than 0.55 to ensure against physical damage (breakage) in routine handling and storage. If aw exceeds 0.68, further drying of the cannabis flower(s) shall be required to ensure that the aw is in the range 0.55-0.65. If aw is less than 0.68, co-storage with a salt-based aw (relative humidity) control sachet(s) designed to maintain the relative humidity between 0.55 to 0.65 can effectively bring the stored cannabis flower(s) into the specified 0.55-0.65 range. Storing cannabis flower with appropriately designed aw (relative humidity) salt-based control sachets intended to ensure a relative humidity of 0.55 to 0.65 in sealed containers can maintain the optimum storage conditions. Maintaining the requisite aw throughout the supply chain from completion of drying through merchandising ensures safety and quality for the consumer.