Understanding Temperature Mapping

Understanding Temperature Mapping

Is your organisation having to start, or repeat, temperature mapping efforts due to increasing regulations on warehouse storage and distribution practices? Are you facing difficulties in maintaining control of the temperature distribution within your storage areas? Are you looking to implement a simple framework of validation testing that aims to establish a sound strategy and approach for performing environmental temperature mapping of storage areas?

There is an increasing awareness that storage areas need to be environmentally mapped to protect product quality and customer safety. A comprehensive temperature mapping study will ensure that your storage area is accurately monitored, properly maintained and in compliance with all the applicable regulations.

Temperature mapping of your warehouse or storage area can be time consuming work, but PharmOut offers practical solutions to simplify the validation process in five steps to ensure that it is cost effective for your business while maintaining the highest standards of quality and reliability.

The PharmOut approach to temperature mapping is described in the flow diagram below:

Temperature mapping

Understand regulatory requirements and comprehend architectural constraints

Before you begin to build the qualification plan, ensure that you understand the following requirements and constraints:

  • Calibration: The calibration of temperature control devices and temperature monitoring devices must be evaluated. Calibration must be within a year’s validity, traceable to a national / international standard such as NIST, and the devices must be calibrated to three points based on the temperature range required for product storage.
  • Environmental range and set point: The environmental range needs to be specified in accordance with the range of the temperature-sensitive product stored in the storage area, as specified in the product specification. This may vary between products and the most critical range should be specified in this case.The set point can be a fixed value or a variable value based on different seasons, external climate conditions, and time. Considerations must be made during planning towards using a variable set point value, with additional or extended mapping periods being the most common approaches.
  • Source of heating and cooling components: Complete a site survey to identify components that may have an impact on the environmental profile of the storage area. The survey must identify sources of temperature variability such as fans, windows, racks/shelves close to the roof or external walls, generators, vents and diffusers. Sensor(s) located near sources of heating or cooling components may cause increased variability of monitoring data.

Create a plan and establish the strategy

PharmOut leverages WHO and ISPE best practices for temperature mapping planning and implementation. One of the first steps when creating a mapping plan is to identify the risks within your storage area. The diagram below shows a typical warehouse layout.

GMP warehouse mapping

The following risks should be considered as part of the mapping plan:

  • Goods stored close to the loading dock may be affected by drafts
  • Goods stored near the north-facing wall and windows may be affected by solar heat
  • Lights can be a source of heat. Goods placed on high racking in close proximity to a light may be at risk
  • Goods movement and other activity in the more trafficable areas of the warehouse is likely to cause drafts
  • Goods stored on tall racking is likely to have a wide temperature variation from top to bottom.

These identified vulnerable areas should have additional sensors placed to gain a better mapping of hot and cold spots. Other risks to consider include total volume of space, air circulation, layout of shelves and racks, HVAC capacities, outside air temperature and humidity, etc.

Develop the mapping strategy detailing the number of sensors to be used, type of loggers to be used, sensor locations and distribution, set point value, data to be generated, and reporting requirements.

Establish a periodic environmental mapping program to ensure continuous compliance. The program should also outline additional mapping requirements such as when changes affect the airflow pattern.

Write mapping protocols, including Installation Qualification (IQ), Operational Qualification (OQ), and Performance Qualification (PQ).

When determining the sensor locations, it is important to document a rationale for choosing the locations, as well as create a diagram that provides a visual map of the locations. It is essential that every sensor be accurately identified by a unique ID number and a defined location.

With regards to determining the number of sensors appropriate for your temperature mapping effort, there is no set formula. Guidelines suggest placing sensors uniformly throughout all three dimensions of the storage area. The number of sensors used must be enough to provide an accurate assessment of the temperature distribution in the area. A rough estimate is that a small area of 12mx12mx12m requires 15 sensors to cover the edges and middle of each dimension, where the sensors are no more than 6m apart.

Sensor distribution

Typical Sensor Distribution: 15 sensors covering all horizontal and vertical planes in a typical three dimensional mapping of this type of warehouse configuration.

If your product is sensitive to relative humidity, it is necessary to use loggers that will record both the temperature and relative humidity in the monitoring locations of your storage area. For humidity mapping studies, the number of humidity loggers to be placed is typically fewer than then number of temperature loggers. These loggers are placed in areas of highest risk (i.e. areas with poor circulation).

If data is gathered or analysed in electronic form, the data storage and analytical software must comply with regulatory requirements (US FDA 21CFR Part 11, PIC/S Annex 11, and EU GMP Chapter 4).

Perform the mapping

Once the risks are identified and assessed, with identified control strategies in place to mitigate any risks, the mapping equipment needs to be set-up and an initial mapping test performed. The sensors must be labelled, programmed and fixed into position as documented in the qualification protocol. New environmentally controlled areas are initially mapped empty (i.e. without products). The purpose of this initial test is to build a temperature / humidity profile and to identify potential areas of unacceptable temperature and humidity for the product during the normal loaded operation mapping.

At the end of the study period, the devices are collected and the data is downloaded and consolidated for analysis.

When the empty study is complete and the empty environmental profile determined, a normal loaded operation mapping is performed. The normal loaded operation mapping is typically performed for a longer period of time than the empty mapping and during extreme seasonal variation such as summer and winter.

Recommend alterations

The results of the mapping exercise must be analysed and compared against the acceptance criteria as defined in the qualification protocol. From the data, the analyst can identify critical areas (hot and cold spots) where the stored product may potentially be exposed to unacceptable temperature and humidity conditions. With this information, you can analyse if alterations are needed to counteract the extremities. This may include making changes to the HVAC system, re-positioning sensors, or re-locating shelves to a modified layout design. Depending on the alterations proposed, an additional mapping study may be necessary to identify the new environmental profile and consequently the correct location of the monitoring sensor(s).

Report results

The temperature mapping report must be simple and easy to understand. Complicated reports tend to attract questions by auditors. The report should include all the data collected during the study, showing data points of each sensor, along with maximum, minimum and acceptable range limits. It should also include details of the testing and alterations if any, conclusions, and plans to conduct additional scheduled mapping.

References

  • WHO Technical Supplement. Temperature mapping of storage areas
  • ISPE Good Practice Guide – Cold Chain Management (2011)

Interested in temperature mapping at your facility? more information

PharmOut have a set of controlled space design templates and Validation Protocols, i.e. IQ, OQ, and PQ templates for sale.