Warehouse Thermal Mapping Guide according to WHO TRS 961 & GDP Rules

In pharmaceutical logistics, temperature control is non-negotiable. Many drugs, biological items, and medical devices require strict storage environments—typically Controlled Room Temperature (CRT) at 15°C to 25°C or Cold Chain at 2°C to 8°C. To ensure that these products do not degrade over time, regulatory bodies enforce Good Distribution Practice (GDP) guidelines. The scientific method used to verify uniform temperature distribution is known as Thermal Mapping.

Why Do We Map Warehouses?

A warehouse is not a static environment. Temperature and relative humidity fluctuate due to several variables:

• External weather conditions (solar radiation hitting the roof).
• HVAC system output and airflow currents.
• Warehouse dimensions, ceiling height, and rack layouts.
• Heat generated by lighting, forklift activity, and personnel.
• Opening and closing of loading dock doors.

A thermal mapping study identifies "hot spots" (where temperatures exceed limits) and "cold spots" (where freezing risks might occur), allowing operators to adjust HVAC designs and avoid placing sensitive inventory in high-risk zones.

The Regulatory Blueprint: WHO TRS 961

The World Health Organization (WHO) Technical Report Series (TRS) 961, Annex 9, outlines the standard guidelines for mapping temperature-controlled storage areas. It defines the structured workflow required for compliance:

1. Pre-mapping Stage (Protocol Design)

Before executing the mapping, a detailed protocol must be written and approved. The protocol defines:

• The target temperature and humidity limits.
• A three-dimensional grid pattern to determine logger placement.
• The number of data loggers required. WHO recommends mapping all three levels of high-racks (top, middle, bottom shelves) to capture stratified heat profiles.
• Logger recording frequency (typically every 5 to 10 minutes).

2. Executing the Mapping Study

Once the protocol is signed off, calibrated data loggers are hung at the designated positions. The study must run continuously for at least 7 consecutive days, capturing:

• Operational days (showing forklift activity, door openings).
• Non-operational days (weekends, to check cooling behavior under static conditions).

Mean Kinetic Temperature (MKT)

Data analysis goes beyond simple averages. Regulatory auditors expect to see the Mean Kinetic Temperature (MKT). MKT is a single-value representation of the overall thermal stress experienced by a product. It places greater weight on higher temperatures, reflecting the non-linear rate of chemical degradation in pharmaceuticals.

Seasonal Mapping: Summer vs. Winter

A single mapping run is insufficient. External conditions in Egypt change dramatically between seasons. A comprehensive GDP validation requires two studies:

• Summer Mapping: Run during the hottest months (typically July or August) to test the HVAC system’s peak cooling capacity.
• Winter Mapping: Run during the coldest months (typically January or February) to check heating consistency or identify draft risks.

Summary Checklist for Warehouse Mapping

Need to map your pharmaceutical store or cold chain facility? Contact QEEMA Egypt. Our team provides turn-key warehouse mapping services, supplying calibrated data loggers, protocol design, sensor installation, MKT calculations, and auditor-ready validation reports.

Frequently Asked Questions