Sector notes
A cold chain reading tells you the temperature. It doesn't tell you what happened in between
A joint FAO/International Institute of Refrigeration study puts the loss from inadequate refrigeration at 526 million tonnes of food a year, 12 percent of the global total. A scheduled spot check only measures the instant someone looked, and the instant is rarely where the excursion was.
Executive summary
526M tonnes
of food lost yearly to inadequate refrigeration — 12% of global production, per FAO/IIR
Core conclusions
- A scheduled spot check only records the temperature at the instant someone looked — it says nothing about a four-hour excursion in between.
- WHO's vaccine cold-chain guidance recommends continuous monitoring specifically because it establishes when an excursion started, how long it lasted, and whether the product is still viable.
- A defensible record needs continuous logging near the product, a cumulative-time-outside-range threshold, and an escalation path that quarantines rather than auto-discards.
A refrigerated shipment can pass every scheduled temperature check on its route and still have spent four hours outside its allowed range between two of them. The check records the temperature at the instant someone looked. It says nothing about the gap, and the gap is where an excursion actually happens.
A 2021 report from the UN Food and Agriculture Organization and the International Institute of Refrigeration puts the scale of what that gap costs at 526 million tonnes of food lost each year to inadequate refrigeration — 12 percent of global food production. Not every tonne of that is a monitoring failure specifically, but a share of it is exactly that: the product was compromised in transit or storage, and nobody knew until it was opened.
Why a spot check misses what it exists to catch
A periodic check assumes temperature drifts slowly and predictably between readings. Reefer units and cold rooms do not fail that way. A door left open at a transfer point, a compressor cycling out, a pallet stacked against the airflow path — each produces an excursion inside a window no fixed check schedule was ever built to land on.
The World Health Organization's vaccine cold chain guidance makes the same point from the regulatory side. WHO specifies the 2°C to 8°C storage range for vaccines and recommends continuous monitoring specifically because it is the only method that establishes when an excursion started, how long it lasted, and whether the product is still viable. A spot check answers none of those three questions once the excursion has already passed — it can only tell you the temperature was fine the last time anyone checked.
What each method can actually tell you
| Scheduled spot check | Continuous sensor monitoring | |
|---|---|---|
| What it records | The temperature at the moment of the check | The full temperature history across the journey |
| A short excursion between checks | Caught only if the check happens to land inside it | Caught every time — the record has no gap |
| Basis for a release or discard decision | An assumption about what happened in between | The measured duration and severity of the actual excursion |
| What it can show an auditor | A logbook that looks clean because it wasn't looking at the right minute | A time-stamped record produced on request |
What a defensible cold chain record needs
- Continuous logging at the product or pallet, not only at the vehicle or room level — the reading that matters is the one closest to what actually spoils.
- An excursion threshold defined as cumulative time outside range, not a single bad reading. WHO's own vaccine guidance discards a dose only once cumulative time outside the approved range crosses a defined limit, checked against a vaccine vial monitor rather than a single temperature spike.
- An escalation path that does not default to automatic discard. WHO guidance is explicit that a suspected excursion should be labelled and quarantined, not thrown out, until someone qualified with product-specific knowledge makes the call.
- A retained record long enough to answer a customer, an auditor, or a recall investigation — the same evidentiary bar a HACCP or FSSC 22000 audit already sets, and a paper log rarely survives cleanly.
None of this is exotic instrumentation. It is a handful of connected sensors and a clearly defined excursion rule, applied to a process most operators already run — which is why it is usually the fastest-paying piece of a logistics digitalisation programme, not the most complex.