Remove the pouch from the refrigerator and let it equilibrate to ambient temperature for 15 min before opening the pouch.
When you are ready to monitor exposure, tear the pouch along the notch, and remove the badge. Keep the pouch for potential use later. Clip the badge to your clothing as close to your breathing zone as possible (e.g. on your shirt collar). This way, the badge will be exposed to the same air you breathe.
Make sure the open end of the badge is not blocked by other objects and is pointing towards the ground so that nothing can fall into the opening to block the air flow into the badge.