blog Temperature vs. Humidity Mapping: Two Critical Differences Paul Daniel Sr. Regulatory Compliance Expert Share Published: Apr 23, 2015 Industrial Manufacturing and Processes Life Science During one of our webinars on Environmental Mapping Qualification, we received a question from a participant on the difference between mapping temperature only, and temperature with RH. Senior Regulatory expert Paul Daniel answers below: Dear Paul, I recently attended your webinar on Mapping Protocols and I wonder – can I use the same methodology you discuss for temperature and humidity mapping studies as with temperature-only mapping studies? Thanks! J Dear J, Short answer: Absolutely, the same methodology would be used for humidity mapping. Almost everything would be the same when considering the protocol document, and the attachments you would use for mapping humidity. Long answer: there are two critical differences in humidity mapping; those are sensor calibration and sensor placement. Calibration: It is rare that a pre-study or post-study calibration can be done for a humidity sensor unless you have a well-equipped calibration lab. In these cases, there would be a single check before the study to verify that calibration certificates were available for your humidity sensors, and that each sensor was within its calibration interval at the time of use. Sensor placement: Generally, the easiest practice is to use the same number of humidity and temperature sensors. This is especially easy if you are using dual sensors like our DL2000 logger. However sometimes it can make sense to utilize fewer humidity sensors. If you do use fewer humidity sensors, it is important that you understand humidity well enough to explain to an auditor what the expected humidity values would be (based on the temperature) in the spots that had only temperature sensors. Our Humidity Calculator is a tool that can help with that. The free Vaisala Humidity Calculator allows you to calculate several humidity parameters from one known value. Make unit conversions on the fly, and see the effects of changing ambient conditions, like temperature and pressure. No more installing software for offline use - just bookmark the calculator page or add it to the home screen on your mobile device. To learn more about spot checking temperature and humidity, here's a short video explaining the use of our HM70 handheld temperature and humidity meter for spot checking.